unesco’s international hydrological programmeimh.ac.vn/files/doc/journal climate change science...

JOURNAL OF CLIMATE CHANGE SCIENCENo.3 - 2017

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UNESCO’S INTERNATIONAL HYDROLOGICAL PROGRAMMEAND CONTRIBUTION OF VIET NAM TO THE PROGRAMME

Tran ThucChairman of Viet Nam National Committee for the UNESCO-IHP

Received: 15 June 2017; Accepted: 21 August 2017

1. IntroductionThe International Hydrological Programme

(IHP), a UNESCO’s intergovernmental scientific co-operative programme in hydrology, is a vehicle through which Member States can upgrade their knowledge of the water cycle and thereby increase their capacity to better manage and develop their water resources. It is the only intergovernmental programme of the UN system devoted to the scientific, educational and capacity building aspects of hydrology.

Since its inception in 1975, IHP has evolved from an internationally coordinated hydrological research programme into a comprehensive programme to facilitate education and capacity building, and enhance water resources management and governance. Originally implemented in six-year phases and now in eight-year phases since 2014, IHP stimulates and encourages hydrological research, and assists Member States in research and training activities.

IHP facilitates an interdisciplinary and integrated approach to watershed and aquifer management, which incorporates the social dimension of water resources, and promotes and develops international research in hydrological and freshwater sciences.1.1. Hydrology Initiatives

As a science and education programme at the global level, the IHP covers a wide spectrum of projects and initiatives. All IHP-related activities are endorsed, recommended and coordinated through the IHP Intergovernmental Council.

IHP’s two cross-cutting initiatives, FRIEND-Water and HELP, interact with all IHP themes through their operational concepts. IHP’s associated initiatives cover projects and activities that contribute to the development and implementation of IHP themes, and are often interlinked with joint initiatives and interagency components.

- FRIEND-Water (Flow Regimes from International Experimental and Network Data). An international research initiative that helps to set up regional networks for analysing hydrological data through the exchange of data, knowledge and techniques at the regional level.

- GRAPHIC (Groundwater Resources Assessment under the Pressures of Humanity and Climate Change). A UNESCO-led project seeking to improve our understanding of how groundwater interacts within the global water cycle, how it supports human activity and ecosystems, and how it responds to the complex dual pressures of human activity and climate change.

- G-WADI (Global Network on Water and Development Information in Arid Lands). A global network on water resources management in arid and semi-arid zones whose primary aim is to build an effective global community to promote international and regional cooperation in the arid and semi-arid areas.

- HELP (Hydrology for the Environment, Life and Policy). A new approach to integrated catchment management by building a framework for water law and policy experts, water resource managers and water scientists to work together on water-related problems.

- IDI (International Drought Initiative). The initiative aims at providing a platform for

Correspondence to: Tran ThucE-mail: [email protected]

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networking and dissemination of knowledge and information between international entities that are actively working on droughts.

- IFI (International Flood Initiative). An interagency initiative promoting an integrated approach to flood management which takes advantage of the benefits of floods and the use of floodplains, while reducing social, environmental and economic risks. Partners: the World Meteorological Organization (WMO), the United Nations University (UNU), the International Association of Hydrological Sciences (IAHS) and the International Strategy for Disaster Reduction (ISDR).

- IIWQ (International Initiative on Water Quality). An initiative aimed at international scientific and policy cooperation to promote research, knowledge generation and dissemination, and effective and innovative policies to meet global water quality challenges in a holistic and collaborative manner towards ensuring water security for sustainable development.

- ISARM (Internationally Shared Aquifer Resources Management). An initiative to set up a network of specialists and experts to compile a world inventory of transboundary aquifers and to develop wise practices and guidance tools concerning shared groundwater resources management.

- ISI (International Sediment Initiative). An initiative to assess erosion and sediment transport to marine, lake or reservoir environments aimed at the creation of a holistic approach to the remediation and conservation of surface waters, closely linking science with policy and management needs.

- IWRM (Integrated Water Resources Management). Implementing IWRM at the river basin level is an essential element to managing water resources more sustainably, leading to long-term social, economic and environmental benefits.

- JIIHP (Joint International Isotope Hydrology Programme). A programme facilitating the integration of isotopes in hydrological practices through the development of tools, the inclusion of isotope hydrology in university curricula and

support to programmes in water resources using isotope techniques.

- PCCP (From Potential Conflict to Cooperation Potential). A project facilitating multi-level and interdisciplinary dialogues in order to foster peace, cooperation and development related to the management of shared water resources.

- UWMP (Urban Water Management Programme). A programme that generates approaches, tools and guidelines which will allow cities to improve their knowledge, as well as analysis of the urban water situation to draw up more effective urban water management strategies.

- WHYMAP (World Hydrogeological Map). An initiative to collect, collate and visualise hydrogeological information at the global scale to convey groundwater-related information in a way appropriate for global discussion on water issues.1.2. Milestones and Main Achievements of the IHP

The Programme started as the International Hydrological Decade (IHD, 1965-1974) and was followed by a long-term programme composed of successive phases of IHP. The IHD was mainly research-oriented and IHP-I (1975-1980) maintained much of the research orientation. However, in response to the concerns of Member States, the next phases were oriented to include practical aspects of hydrology and water resources. Hence IHP-II (1981-1983) and IHP-III (1984-1989) were planned under the theme Hydrology and the Scientific Bases for Rational Water Resources Management.

- The International Hydrological Decade (IHD) (1965-1975) is an outstanding example of international scientific and technical cooperation. It enabled collaboration between over 100 countries, bringing about important scientific and practical results, notably by: (i) Helping to develop a rational attitude towards the utilization and management of the water resources of the earth; (ii) Contributing to the understanding of the processes and phenomena occurring in the hydrosphere; (iii) Assessing the surface and groundwater resources and


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their variability; (iv) Facilitating the international cooperation necessary to conduct research and to compile scientific and technical data necessary to provide guidelines and information for the advancement of hydrological sciences; and (v) Promoting research, education, training and technical assistance in hydrology, as well as facilitating the development of hydrology programmes, not only within UNESCO, but also in relation to other UN organizations and NGOs.

- The First Phases (1975-2001): Through its first phases, starting from 1975, IHP played an important role in: (i) Contributing to the assessment of water resources; (ii) Developing methodologies of water management; (iii) Improving knowledge of hydrological processes; (iv) Providing an effective transfer of technology, with significant contributions from postgraduate courses in training competent hydrologists and developing hydrological knowledge, including educational material; and (v) Transmitting and exchanging knowledge through its publications.

Since the inception of the IHD in 1965, and later the IHP in 1975, much progress has been achieved regarding methodologies for hydrological studies and training and education in the water sciences. Although the general objectives remain valid, greater emphasis is being placed on the role of water resources management for sustainable development and the adaptation of the hydrological sciences to cope with the expected changing climate and environmental conditions. Another important objective is to integrate the developing countries into the world-wide ventures of research and training. The principal modes of execution of IHP have been working groups, symposia, workshops, publications and extra-budgetary projects, the latter especially through the UNESCO regional offices where regional hydrologists are located.

- The Fourth Phase (1990-1995): Hydrology and Water Resources for Sustainable Development in a Changing Environment. The IHP-IV comprised three sub-programmes: (i) Hydrological Research in a Changing Environment; (ii) Management of Water Resources for Sustainable Development; and (iii) Education, Training and the Transfer of Knowledge and Information.

- The Fifth Phase (1996-2001): Hydrology and Water Resources Development in a Vulnerable Environment. The eight Themes of IHP-V was divided as follows: (i) Global hydrological and bio-geochemical processes; (ii) Eco-hydrological processes in the surficial zone; (iii) Groundwater resources at risk; (iv) Strategies for water resources management in emergency and conflicting situations; (v) Integrated water-resources management in arid and semi-arid zones; (vi) Humid tropics hydrology and water management; (vii) Integrated urban-water management; and (viii) Transfer of Knowledge, Information and Technology (KIT).

While recognizing that IHP’s first phases had been instrumental in promoting hydrological sciences, an external evaluation in 2003 on IHP’s fifth phase suggested broadening the scope of IHP beyond purely scientific hydrological concerns. From its sixth phase on, the Programme began to focus primarily on water resource management and related cultural, societal and capacity building issues, evolving from a “pure science only” ethos to one of “science within society”.

- IHP-VI onwards: Shifting to a Holistic and Integrated Approach. The Sixth Phase of IHP represented an important turning point for the Programme, whose focus shifted from studying the occurrence and distribution of water in the environment towards societal aspects of water resources, highlighting the need for better assessment and management, in particular at the transboundary level. In particular, the Programme: (i) Created a network of water professionals at all levels; (ii) Influenced policymaking, research and capacity building, highlighting the fact that institutional and economic issues are fundamental to the efficient use of water, conservation and depletion; (iii) Produced action-oriented and policy-relevant activities and outcomes in support of the “global agenda for sustainability”, through training and capacity development in the field of water governance; (iv) Encouraged national activities through programmes broadly found to be comprehensive, relevant and


useful to almost all countries; (v) Addressed Member States as main audience, through National Committees and the UNESCO Water Family, in collaboration with governmental bodies, NGOs, and academic and research institutions; (vi) strong global relevance, enhanced by IHP’s work with and inside developing nations, promoting South-South and North-South exchanges, its ability to propose conventions and take an active role in the prevention of water conflicts, and its contributions to the WWDRs; and (vii) Mobilized scientific opinion with only limited resources;

- The Sixth Phase (2002-2007): Water Interactions: Systems at risk and societal challenges. IHP-VI was intended to shift the scope of the IHP itself and to focus more on societal aspects of water resources, thus raising the need for improved, more efficient assessment and management of water resources, especially at the transboundary level. IHP-VI had five main themes divided into focal areas as follows: (i) Global Change and Water Resources; (ii) Integrated Watershed and Aquifer Dynamics; (iii) Land Habitat Hydrology; (iv) Water and Society; and (v) Water Education and Training.

- The Seventh Phase (2008-2013): Water Dependencies: Systems under Stress and Societal Responses. The core pillars of IHP-VII, structured into themes and focal areas, are the following: (i) Promoting leading-edge research that provides timely and appropriate policy-relevant advice to Member States; (ii) Facilitating education and capacity development as a response to the growing needs linked to sustainable development; (iii) Enhancing governance in water resources management to achieve ecosystem sustainability.2. The Eighth Phase (2014-2021) of IHP

The new phase of IHP follows the Millennium Development Goals (MDGs) era and envisions new challenges to be set in Rio+20. During its eighth phase, IHP aims to improve water security in response to local, regional, and global challenges. For our purpose, water

security is defined as the capacity of a population to safeguard access to adequate quantities of water of acceptable quality for sustaining human and ecosystem health on a watershed basis, and to ensure efficient protection of life and property against water-related hazards such as floods, landslides, land subsidence, and droughts. Given populationgrowth, degradation of water quality, growing impact of floods and droughts and other hydrological effects of global change, water security is an increasing concern. Consequently, the overarching focus of the IHP eighth phase is encompassed in its title “Water security: Responses to local, regional, and global challenges.” To deal with the complex, rapid environmental and demographical changes (e.g., population growth and vulnerability to hydrological disasters, global and climate changes, uncontrolled urban expansion, and land use changes) holistic, multidisciplinary and environmentally sound approaches to water resources management and protection policy will be sought. The eighth phase of IHP reflects a deeper understanding of the interfaces and interconnections between the water-energy- food nexus, which aims to further improve integrated water resources management (IWRM). The role of human behavior, cultural beliefs, and attitudes toward water, and the need for research in social and economic sciences to understand and develop tools to adapt to human impacts of changing water availability, are challenges to be addressed in the eighth phase of IHP.

IHP-VIII focuses on six knowledge areas translated into themes. These themes address issues pertaining to managing water security, water quality and pollution control; adaptation to the impacts of climate change and natural disasters on water resources; management and protection of groundwater resources for sustainable living and poverty alleviation in developing countries and in arid and semi-arid regions and small islands; integration of catchment scale ecohydrological concepts and processes in advanced water management models; management of water resources for human settlements of the future; and water


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education as a key element to attain water security. IHP-VIII has been designed to allow for a high degree of connectivity between topical areas. To connect thematic contents, crosscutting issues are addressed across the defined areas of knowledge or themes and are focused on: conjunctive surface water-groundwater sustainable management in an IWRM based on holistic and environmentally sound approaches as well as social and cultural traditions; integrated management consistent with transboundary water resources to prevent and/or overcome potential international conflicts over water; evaluation of the impact of key global change drivers on water resources availability and quality and population vulnerability; formulation of the framework for water governance policy based on multilevel and trans-sectoral approaches and integration of water stakeholders and general public; endorsement of the effort in water education, training, capacity building and hydrological research. In particular, IHP-VIII endorses the UNESCO goals to further equal opportunities for women and children.

The Eighth Phase of IHP focuses on six thematic areas:

- Theme 1: Water-related disasters and hydrological changes: (i) Risk management as adaptation to global changes; (ii) Understanding coupled human and natural processes; (iii) Benefiting from global and local earth observation systems; (iv) Addressing uncertainty and improving its communication; (v) Improving the scientific basis for hydrology and water sciences for preparation and response to extreme hydrological events.

- Theme 2: Groundwater in a changing environment: (i) Enhancing sustainable groundwater resources management; (ii) Addressing strategies for management of aquifer recharge; (iii) Adapting to the impacts of climate change on aquifer systems; (iv) Promoting groundwater quality protection; (v) Promoting management of transboundary aquifers.

- Theme 3: Addressing water scarcity and quality: Improving governance, planning, management, allocation, and efficient use

of water resources; (ii) Dealing with present water scarcity and developing foresight to prevent undesirable trends; (iii) Promoting tools for stakeholder involvement and awareness, and conflict resolution; (iv) Addressing water quality and pollution issues within an IWRM framework improving legal, policy, institutional, and human capacity; (v) Promoting innovative tools for safety of water supplies and controlling pollution.

- Theme 4: Water and human settlements of the future: Game-changing approaches and technologies; (ii) System-wide changes for integrated management approaches; (iii) Institution and leadership for beneficiation and integration; (iv) Opportunities in emerging cities in developing countries; (v) Integrated development in rural human.

- Theme 5: Ecohydrology-engineering harmony for a sustainable world: (i) Hydrological dimension of a catchment - identification of potential threats and opportunities for sustainable development; (ii) Shaping of the catchment ecological structure for ecosystem potential enhancement - biological productivity and biodiversity; (iii) Ecohydrology system solution and ecological engineering for the enhancement of water and ecosystem resilience and ecosystem services; (iv) Urban Ecohydrology - storm water purification and retention in the city landscape, potential for improvement of health and quality of life; (v) Ecohydrological regulation for sustaining and restoring continental to coastal connectivity and ecosystem functioning.

- Theme 6: Water education - key for water security: Enhancing tertiary water education and professional capabilities in the water sector; (ii) Addressing vocational education and training of water technicians; (iii) Water education for children and youth; (iv) Promoting awareness of water issues through informal water education; (v) Education for transboundary water cooperation and governance.3. Contributions of the Viet Nam National Committee for the IHP

The Viet Nam National Committee for International Hydrology Programme (IHP


Viet Nam) was established under the Decision No 122/CT on April 17th, 1991 of the Prime Minister of Viet Nam. The IHP Viet Nam works under the Sub-Committee on Natural Sciences of the Viet Nam National Commission for UNESCO. The Committee office is now located at the Viet Nam Institute of Meteorology, Hydrology and Climate Change.

In the region, IHP Viet Nam works with the coordination of the IHP Regional Steering Committee for the Southeast Asia and the Pacific (AP-RSC), whose members are representatives from the 17 IHP National Committees, to carry out IHP activities at regional level. Since 1993, annual RSC meetings have been convened in different countries of the region to report, evaluate and review various activities carried out within the framework of IHP, as well as to design new ones; in conjunction with the RSC meetings, annual international conferences and symposia have been held.

In co-operation with UNESCO Jakarta and the participating member states, the AP-RSC has co-ordinated a wide range of initiatives over ten years so far, including research studies, technical projects, workshops, training courses and annual symposia, bringing together many specialists involved in water-related activities. The most notable regional initiatives made

possible by the cooperative efforts of the RSC are: the AP-FRIEND (Asian Pacific Flow Regimes from International and Experimental Network Data) project, the Asian Pacific Water Archive and the Catalogue of Rivers.

IHP Viet Nam has coordinated with national agencies and organizations in various fields such as Hydrometeorology, Climate Change, Irrigation, Water Resources and Environment.

In recent years, IHP Viet Nam has participated in activities such as:

- Participating in annually IHP Asia-Pacific conferences, in: Mongolia (2016), Indonesia (2015), Indonesia (2014), Korea (2013), Malaysia (2012), Japan (2011), Viet Nam (2010), China (2009), Mongolia (2008), Philippines (2007), Thailand (2006), Indonesia (2005), Australia (2004), Fiji (2003), Malaysia (2002), Viet Nam (2001), New Zealand (2000), China (1999), Korea (1998), Thailand (1997), Indonesia (1996), Japan (1995), Cambodia (1994), Philippines (1993).

- Attend and present scientific papers at annually IHP Asia-Pacific scientific conferences held in conjunction with annual conferences.

- Organize scientific workshops within IHP Asia Pacific in Viet Nam, organize training courses on hydrology, water resources, natural disaster prevention and climate change, and send staffs to participate in training courses organized by IHP Asia Pacific.

- Contribute to the Asian Pacific Flow Regimes from International and Experimental Network Data project, and the development of Asian Pacific Water Archive and the Catalogue

Figure 1. IHP International Workshop in Viet Nam

of Rivers.- Publish technical books and guidelines on

hydrology, water resources and climate change.- Coordinate with domestic and foreign


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agencies to exchange professional knowledge on hydrological and water resources issues.

- Offer postgraduate courses and supervise doctoral students at the United Nation University in Japan, the Viet Nam Institute of Meteorology, Hydrology and Climate Change and other universities abroad and in Viet Nam.

In 2001, IHP Viet Nam collaborated with UNESCO-IHP to organize International Symposium on Achievements of IHP in Hydrological Research and 9th Regional Steering Committee for IHP in Southeast Asia and the Pacific.

The AP-FRIEND meeting of “Intensity - Frequency - Duration and Flood Frequency Determination” in Ho Chi Minh City from 9 to 10 March 2009.

IHP Viet Nam cooperated with UNESCO-IHP to organize the International Conference on Hydrological Regime and Water Resources in the Context of Climate Change (HWCC 2010) in conjunction with the 18th Regional Steering Committee for IHP Southeast Asia and the Pacific in Ha Noi from 8 and 9 November 2010.

In the coming years, the activities are oriented towards the goal of IHP-VIII period 2014-2021, IHP Viet Nam focuses on the following issues: (i) Water resources security; Water for sustainable cities; Disaster preparedness for schools and communities; Sustainable water resources management; Effectively managing rivers, national aquifers and transboundary aquifers; Raise awareness of all levels of climate change; (ii) Water, Energy and Food Nexus to improve the capacity of

Figure 2. IHP 18th Regional Steering Committee Meeting

Figure 3. Workshop on Rainfall Intensity Frequency Distribution and Design Flood

Determination

integrated water resources management; (iii) Propagate and disseminate themes of the eighth phase of UNESCO-IHP activities: 2014-2021 in agencies and schools; (iv) Actively participate in the IHP Asia-Pacific activities and contribute positively to Annual Scientific Conferences and Workshops; (iv) Registered and successfully organised of the 28th IHP-RSC meeting in Viet Nam.

References1. International Hydrological Programme (2014), IHP-VIII: Water Security - Responses to Local,

Regional, and Global Challenges (2014-2021).2. UNESCO (2015a), 50 Years of Water Programmes for Sustainable Development.3. UNESCO (2015b), Milestones and main achievements of the IHP (1965-2015), http://en.unesco.

org/50-years-unesco-water-programmes/milestones.4. Viet Nam National Committee for the IHP, Annual reports to the IHP.


HYDROLOGY AND WATER RESOURCES PHD PROGRAM AT VIET NAM INSTITUTE OF METEOROLOGY, HYDROLOGY AND CLIMATE CHANGE

Nguyen Van ThangDirector General of Viet Nam Institute of Meteorology, Hydrology and Climate Change


1. Achievements in PhD trainingAs one of leading national institution in

Viet Nam, Viet Nam Institute of Meteorology, Hydrology and Climate Change (IMHEN) has been training high-level professionals for the country since 1982. It is considered as one of the best prestige training unit. The Institute is also the unique one in Viet Nam launching Climate Change and Sustainable Development PhD Program.

In 1982, Viet Nam Institute of Meteorology, Hydrology and Climate Change was assigned by the Government to provide post-graduate education and training professional fields including meteorology, climatology, hydrology and oceanography. In order to meet the increasing demand and requirement on education and training of other professional fields, IMHEN has been allowed by the Ministry of Education and Training to launch Natural Resource and Environmental Management PhD Program since 2011 and Climate Change and Sustainable Development PhD Program since June, 2014. By 2017, there has been 48 PhDs graduated from IMHEN in the fields of Meteorology and Climatology, Hydrology, Oceanography, Natural Resources and Environment. There are other 49 PhD candidates studying and researching at IMHEN. Graduated PhDs from IMHEN are highly qualified and meet the requirements of their agencies.

Currently, postgraduate training program at IMHEN has 28 faculty members, including 01 professor, 08 associate professors and 19 PhDs graduated both domestically and internationally.

Most of them are leading experts in meteorology, hydrology, environment and climate change in Viet Nam. Faculty members of IMHEN are also participating in undergraduate and postgraduate training in meteorology - climate, hydrology, hydraulics, water resources, oceanography, climate change in other training institutions such as: University of Natural Sciences, Center for Environmental Resources Research - Viet Nam National University, Ha Noi University of Resources and Environment, Thuy Loi University, Ha Noi National University of Education, National University of Ho Chi Minh City, Da Nang University,... Besides, they are also participate in postgraduate training with international universities like: UN University (Japan), University of Cologne, University of Dresden (Germany), Asian Institute of Technology (AIT) (Thailand), Monash University (Australia),...

Hydrology and Water Resources PhD Program at IMHEN has a long training history Since 1980s, IMHEN has focused on intensive training in hydrological calculations, hydrological design, mathematical modeling and the application of new technologies and techniques in hydrological on water resources research. By the late 1990s, the number of PhD candidates in hydrology and water resources increased together with the expansion of professional fields. The quantity and quality of supervisors has been improved and many new research directions have been applied such as: reservoir operation system; forecasting and warning natural disasters; urban hydrology; river dynamics; applying of GIS and remote sensing in hydrology and water resources,...

In order to accommodate with the Viet Nam strategy for science and technology development, there is a demand to broaden

Correspondence to: Nguyen Van ThangE-mail: [email protected]


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research topics for PhD education and link PhD training to scientific research. Additionally, there is a need to quickly reach the advanced level in the region, approach the topic of International Hydrological Programme (IHP) in each period.

Many new training fields have been established such as integrated river basin management, flash flood warning, developing decision support system, ecological hydrology; water economy, the impact of climate change on hydrology and water resources.

In order to accommodate with the training requirements, IMHEN has developed a system of lectures, courses, doctoral topics updated with the newest knowledge and information.

The system of reference books is supplemented as follows: Urban Hydrology; Flash floods; Impacts of climate change on water resources; River dynamics; Statistics in hydrology; River hydraulics; Integrated water resources management etc.

By 2017, there are 12 Hydrology and Water resources PhD candidates graduated and 6 PhD candidates studying and researching at IMHEN.2. Strategic orientation

In coming years, IMHEN aims to remains as a leading research and training institution in Viet Nam in the fields of meteorology, hydrology and climate change. Therefore, IMHEN’s PhD program need:

- To focus on updating training contents; to actively develop a mechanism for close coordination with agencies of the Ministry of Natural Resources and Environment for training. Training must be linked to the high demand of human capacity in industry as well as the society. A detail plan to broaden training fields at IMHEN need to be developed.

- To continue stepping up international co-operation in scientific research, technological development and human resource training; to strengthen the exchange and learning experiences from advanced countries in international scientific conferences and seminars to introduce and popularize scientific and technological research achievements of Viet Nam; to facilitate the support of international scientists to support research and solve problems in

Viet Nam. Studying and developing training cooperation models with prestigious international training institutions in order to raise the quality and training position of the Institute. This will provide access to the world’s leading standards of academic education and the potential for collaborative research in the fields of hydrology. It also provides a platform for the exchange of professors and lecturers, which is a key activity in IMHEN’s professional work. Inviting the hydrology and water resources leading experts in universities and training institutions in the world to participate in teaching and coordinating doctoral training at the Institute.

- To establish close relationship with IHP, follow IHP VIII topics in training.

- To improve facilities, libraries, computers, etc.- To achieve these strategic objectives,

Hydrology and Water Resources PhD Program will focus on specific criteria:

Advanced: To reach the training level of hydrology and water resources doctoral training program at some advanced training institutions in Asia and in the world;

Systematic: Inheritance, developing doctoral training program of the Institute, referencing and inheriting training programs in hydrology and water resources of other training institutions in country and abroad;

Interdisciplinary: Interdisciplinary direction with the fields of water resources, agriculture, environment,...

Inter-college transfer: The training program must be advance and inter-college transferable. 3. Conclusions

Hydrology and Water Resources PhD Program at IMHEN is being strengthened in accordance to the regulations of the Ministry of Education and Training. In order to improve the competitiveness of PhD training, it is necessary to attract high quality, enthusiastic and creative human resources. In addition, IMHEN’s Hydrology and Water Resources PhD Program should focus on disaster prevention and mitigation, water resources management and other key professional fields to provide more knowledgeable researchers and skillful staffs on hydrology and water resources.


GROUNDWATER RESOURCES IN VIET NAM: POTENTIAL AND CHALLENGES

Pham Quy Nhan(1), Tae Yoon Park(2)

(1)Ha Noi University of Natural Resources and Environment, Viet Nam (2)Yonsei University, R.P. Korea


Abstract: Groundwater is a precious resource in Viet Nam, especially in areas with a lack of other available water resources. Intensive investigation of groundwater resources has been undertaken over the past five decades and identified 26 water-bearing units in 7 regions. Groundwater resources are represented by potential reserves, classified by hydrogeological regions. The total groundwater potential reserves in the country reach nearly 133 million m3/day, which equals 48.5 billion m3/year. Groundwater resources are exploited for many purposes such as drinking, manufacturing, irrigating, aquacultural cultivation in Red river/aquacultural cultivation plain, in Southern plain and in the Central Highlands. During groundwater extraction, some challenges have been arise such as groundwater contamination of Nitrogen, Arsenic etc., Land subsidence as a result of overuse for example in Ha Noi, Ho Chi Minh City, Ca Mau peninsular and groundwater salinization in coastal aquifers where there is about 3,260 km coastal line with developing areas and impacts of climate change and sea level rise.

Keywords: groundwater resource, potential, reserve, contamination, climate change.

1. IntroductionViet Nam is located in South east Asia;

towards the East Sea covering an area of about 329,560 km2. Viet Nam has a tropical climate in the South and monsoonal in the North. Annual rainfall is substantial, ranging from 1,200 mm to 3,000 mm. About 90 percent of the precipitation occurs during the summer.

The whole territory of Viet Nam can be divided into 7 natural geographic regions: (I) North West, (II) North East, (III) Red River Delta (IV) North of Centre, (V) Coastal area of South of Centre, (VI) Central Highlands, and (VII) Mekong River Delta. Viet Nam has 3,260 km of coastline from the North to South with different natural characteristics (Vu, 1988).

The first almost 100 m deep production well in Ha Noi was developed in the late 19th

century during French colonization period, but understanding on groundwater system was quite limited. Not until 1954 were intensive investigations on geology and hydrogeology

developed. Viet Nam Geological Survey is a leading organization carring out most of the projects for exploration of groundwater resources (Vu, 2013). Since the renovation period from 1990, many consultating companies have been carrying out investigations of groundwater resources for water supply as well (Vu, 2013). In addition, national research projects and international projects have also been carried out to better understand groundwater resources in the country. This new study on groundwater’s potential reserve, is based on a great deal of information from previous investigations, studies and data.2. Hydrogeological settings

Surveys and researches on hydrogeology in Viet Nam over the past five decades have identified 26 water-bearing units, including four porous water-bearing complexes, 15 fissured (including fissure-pore, fissure-bed, and fissure-karst) bearing complexes, and seven water-bearing zones in tectonic faulting settings (Vu, 1988). Distributions, capability and water quality of water-bearing units are diversed. Among the water-containing units, those occur in Quaternary

Correspondence to: Pham Quy NhanE-mail: [email protected]


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unconsolidated sediments, Paleozoic-Mesozoic carbonates and Neogene-Quaternary volcanic rocks are essential to socio-economic development for their spacious distribution, water abundance and of high quality (Figure. 1)

Based on the results of hydrogeological investigations carried out during more than half of a century on the territory of Viet Nam, 26 water-bearing units have been established, including 4 intergranular water-bearing complexes, 15 fissured water-bearing complexes (including fissure-intergranular, fissure-seam and fissure-karstic) and 7 water-bearing zones in tectonic faults (Vu, 1988). They have different distributive areas, water-bearing capacity and water quality that are displayed in the accompanied hydrogeological map, among them the water-bearing units in Quaternary loose sediments, in Paleo-Mesozoic carbonate beds and in Neogene-Quaternary basalts are the most important ones for the economy and people’s livelihood, because they have large distributive areas, abundant water-bearing capacity and good water quality (Figure 1).2.1. Water-bearing complexes in Quaternary unconsolidated sediments

The water-bearing complexes in Quaternary unconsolidated sediments are largely distributed in the Northern, Southern and South-Central coastal plains. There are two main aquifers as follows:

Aquifer in Holocene sediments is distributed widely in all plains. Their lithological composition consists mainly of sand, clay, mixed clay and sand and mud with thickness ranging from 5-10 to 70-80 m. The water is loosed or weakly pressurized. In the dry season, the water table usually lies between 3 and 5 m deep. In rough terrains, water level may be as deep as 7-8 m. In the rainy season, the water table may rise to the surface. In low land coastal areas, groundwater level fluctuates with tides. Boreholes conducted in these areas show the specific discharge capacity varies from 0.2-0.5 to 4-5 l/sm. The permeability coefficient of the deposits changes in a wide interval, from < 1 to tens of meters/day.

The water quality of this aquifer is complicated. The water in the areas located relatively far from the sea is of good quality with the total dissolved solids (TDS) lower than 0.5 g/l, with main chemical substances being calcium bicarbonate. The water in coastal areas is usually salinized with the TDS rising up to 2-3 g/l, in some places, to 10-15 g/l or higher. However, in these areas sometimes pockets of fresh water are found withins and dunes. Due to the exposure of the water-bearing formation on the surface, the water may be easily contaminated by nitrogen compounds, bacteria and pesticides thus becoming unsafe. Another common feature is very high iron content in the water (1-2 mg/l, in sometimes up to 5-10 mg/l) that is distributed irregularly in the area.

In general, the quality of water in the Holocene aquifer is not good. Because of its large distribution, relatively abundant reserves, easy exploitation conditions it has been an important source of rural and coastal water supply; although special attention must be given to water treatment and disinfection measures.

Aquifer in Pleistocene sediments: These aquifers are widely spread in plain areas, almost covered by Holocene deposits, exposed partially in some marginal areas. The sediments are sand, pebble and gravel interceded by some clay layers. The water table occurs from 5-10 to 70-80 m deep. The thickness varies from some tens (in the Northern Plain) to 150-200 m (in the Southern Plain). The water-bearing capacity is relatively high. The specific discharge of drilling wells usually reaches 2-5 to 8-10 l/sm. In covered areas, the water is confined and the water level usually fluctuates from 5-10 m under the surface to 0.5-1.2 m above the surface.

The water quality of the Pleistocene aquifers changes rather irregularly. In the central and marginal areas, distant from the sea, the water quality is usually good with the TDS not surpassing 0.5 g/l. Its main chemical components contain calcium and sodium bicarbonates. In coastal areas, the water is salinized with the TDS increasing to 1-2 g/l, in some places, up to 5-7 g/l or higher; the chemical substances change into


sodium chloride or sodium-magnesium chloride-bicarbonate. However, similar to the Holocene aquifer, in these areas, there are pockets of fresh water of good quality as found in the Northern (Red River) Plain. In Thai Binh - Nam Dinh area, the groundwater is salinized, but 2 freshwater strips are found there: the first extends from Hai Hau to Giao

Thuy districts, having an area of 800 km2; the second spreads from Hung Ha to Diem Dien districts, where the water has the TDS not exceeding 0.4-1.5 g/l. In the Duyen Hai, Cau Ke, Tra Cu areas (Tra Vinh province), in the Southern (Nam Bo) Plain regardless of being located near the sea, the groundwater has the TDS usually about 1 g/l or lower.

Figure 1. Distribution of main water-bearing units in Viet Nam (Source: Vo Cong Nghiep et al., 1995)


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In general, this is the aquifer of great significance, especially for large water supplies. The water-supply plants of the Ha Noi City extract mainly its groundwater. Many other cities, such as Phuc Yen, Dap Cau, Da Nang, Quy Nhon, Ba Ria, Ho Chi Minh City (Binh Chanh, Hoc Mon Dist.), Thu Dau Mot, Vinh Long, etc. use mainly the water from just this aquifer.2.2. Water-bearing complexes in Paleozoic- Mesozoic carbonate sediments

The Paleozoic-Mesozoic carbonate formations occur mainly in the Northeastern, North-Central, Southeastern and Southwestern regions. Their lithological composition consists mainly of bedded or massive limestone; usually fractured, strongly karstified, forming large caves and underground rivers and streams. The total thickness of the formation reaches thousands of meters.

The water presents in fissured or fissured-karstic forms, practically not forming a continuous hydraulic system, but existing as bands or zones. Due to the heterogeneity of water-bearing character, the water-bearing capacity changes both horizontally and the vertically. The depth of the water level changes from first meters to 20-30 m or more in some places. A number of water springs are exposed, but the density of occurrence is different. The spring discharge changes from about 1 l/s to hundreds of liters per second. The specific discharge of drilled wells changes from 0.01 l/sm to 50 l/sm, usually greater than 0.5 l/sm. The hydraulic conductivity coefficient varies strongly, usually from 10 to 50 m/day.

The TDS of water is usually less than 0.5 g/l. Only in coastal areas, affected by the tide fluctuation and distributed along some large faults, highly mineralized water originated from deep levels the TDS may be as high as tens of g/l. The main chemical components of the water are calcium bicarbonate or calcium- sodium chloride-bicarbonate. The water quality, in general, is good, except for salinized and residential areas, industrial and agricultural areas and livestock farms where the water is easily polluted due to the presence of many karstic funnel caves exposed on the surface. In some mountainous areas (such as Cao Bang, Ha

Giang), the water has very low TDS (super fresh), a factor affecting the people’s health (e.g., causing calcium and magnesium deficiency diseases). In general, the carbonate water-bearing complexes play an important role, but the investigation and exploitation of this resource are still feeble. 2.3. Water-bearing complexes in Neogene-Quaternary basalts

Basalt formations are distributed mainly in the Central Highlands and Southeastern regions, and scattered in some other areas (such as Northwestern, Phu Quy, Vinh Linh, Quang Ngai, Phu Yen). The thickness of the basalt cover varies from tens to several hundreds of meters, especially in the Pleiku plateau the total thickness reaches up to 400 m. Basalts occurred in a number of episodes and eruption phases, clearly observed in some cross-sections. The basaltic stratigraphy includes intercalated layers of porous and massive lavas, weathering and fresh products. This lithological variety forms a heterogeneous water-storage capacity (the most abundant container is porous and sub-weathered lava flows).

The water level in the basalt changes from few meters to 30-40 m or more. Elsewhere water ejects from drilled wells to the surface. At a well in Dak Mol (Dak Nong province) water spouts up to 18 m into the air. Water is more abundant in the central area of basalt center or inproximity of volcanic craters as compared to marginal sites. The discharge of exposed springs and wells varies from a few to 30-40 l/s. The Co Dam springs in Buon Ma Thuot city show the discharge rate up to 80 l/s. The specific discharge of boreholes normally varies from 0.1-0.5 l/sm to 6-7 l/sm. The hydraulic conductivity changes in an interval between 0.1 and 10 m/day. In some areas (such as Pleiku, Buon Ma Thuot, Xuan Loc), it is noticeable that basalt formation, regardless of having high water storage capacity, due to the complete draining of water when boreholes are drilling through fractured zones, still causes water loss from upper fractured zone down to deeper one.

The quality of groundwater in basalts is generally good. The TDS is usually lower


than 0.5 g/l. The water consists of sodium bicarbonate, sodium and sodium-magnesium bicarbonate-chloride.

The groundwater in basalts is essential for economic development, especially for the irrigation of industrial plantations in the Central Highlands and Southeastern regions.

Apart from the above-mentioned water-bearing complexes which have great significance in the large-scale water supply to wide areas, in the Southern Plain, the Pliocene and Miocene aquifers also play an important role.

Terrigenous sediments and complex formations have lesser water abundance, but appear to be significant as small- and medium-scale water suppliers. In metamorphic and intrusive formations, groundwater exists limitedly only in fractured and tectonically deformed zones; thus may be considered as a small-scale water supplier. 3. Groundwater potential

Many hydrogeologists, using different methodologies and achieving different results, have evaluated the groundwater resources in Viet Nam.

According to the National Research Project

“Evaluating the sustainable character of the extraction and use of the groundwater resource on the territory of Viet Nam: Strategic orientation of the rational extraction and use and preservation of the groundwater resource to 2020” completed by the University of Mining and Geology (Pham et al., 2005), groundwater potential reserves in Viet Nam were ever determined.

The research outcomes have incorporated previous results as well as updated information using newly published literature and calculation methods for the entire territory. The results achieved are highly reliable. Groundwater resources are represented by potential reserves and classified by hydrogeological regions (Table 1). As calculated above, the total potential reserves of groundwater in the country reaches nearly 133 million m3/day, which is 48.5 billion m3/year, plus about 870 billion m3/year of surface water, the total renewable water resources of Viet Nam are 918.5 billion m3/year. According to data published in 2002-2003 by the World Water Resources Institute (WRI), the amount of renewable freshwater resources of Viet Nam is 11.189 m3/person, folding 1.7 times the world average (6,537 m3/person/year).

Table 1. Groundwater potential reserves in Viet Nam

No Hydrogeological region

Symbol Area (km2)

Important water bearing formations Potential reserves (m3/day)

1 Northwestern I 35,530 Carbonate, terrigenous formations 15,521,3382 Northeastern II 66,434 Carbonate, terrigenous formations 27,995,3743 Northern

(Red River) PlainIII 8,204 Quaternary unconsolidated sediments;

carbonate and terrigenous rocks (marginal)

17,191,162

4 North-central IV 51,095 Quaternary unconsolidated sediment (plain); carbonate and terrigenous rocks (mountainous); basalt (locally)

15,830,784

5 South-central coastal region

V 44,245 Quaternary unconsolidated sediment (plain); terrigenous formations (mountainous); basalt (locally)

12,839,864

6 Central Highlands VI 54,701 Basalt, terrigenous formations 18,009,3887 Southern Plain VII 44,789 Quaternary unconsolidated sediments;

terrigenous rocks, basalt (Eastern)25,486,080

Total 304,998* 132,873,990

* Not to mention the areas of the islands (Pham et al., 2005)


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Over the past five decades, the Viet Nam Geological Survey and Consultation Companies have been carrying out the exploration of groundwater in over 200 sites, mainly urban areas and important economic zones, with the developed reserves reaching the industrial categories (A+B) of nearly 2 million m3/day, C1 category=2.8 million m3/day and C2 category=18.5 million m3/day. These are the insufficient synthetic data taken from reports on groundwater exploration serving the centralized water supply.

Nowadays, most groundwater (over 80%) is extracted for water supply. At present, the water source supply to Ha Noi City is almost from groundwater with the total abstraction of about 712,222 m3/day (not including rural water supply and private production wells). In each region, there are updated statistical of Groundwater abstraction such as in North-West and North-East: 356,274 m3/day, Red River Delta: 1,799,892 m3/day (not including Ha Noi City), North Central coast: 201,984 m3/day, South Central coast: 185.445 m3/day, Central Highlands: 170.642 m3/day, South-East: 268,346 m3/day and Mekong River Delta: 483,759 m3/day (not including Ho Chi Minh City with 1,270,700 m3/day). The groundwater is used effectively also in agricultural production, especially in provinces in Central Highlands and in the South Eastern in the irrigation of industrial plantation crops. 4. Challenges

Viet Nam has been facing major challenges associated with contamination of groundwater resources by industries, agricultural pesticide and fertilizer, aquaculture activities, mining, and waste disposal. While no detailed scientific assessment has been undertaken, the areas most “vulnerable” to the effects of groundwater pollution and salt intrusion are places where the aquifers are unconfined, where there are many potential polluting activities, and where communities and cities are dependent on groundwater as the main source of drinking water supply. In many places, the groundwater shows signs of contamination of

pollutants (such as Nitrogen, Arsenic, Heavy metals, Bacteria, Organic compounds) caused by households, industrial waste, the use of fertilizers and insecticides in agriculture.

The quality of groundwater in natural conditions is, in general, good, but in many places, the Fe and Mn contents are very high (especially, in the water in Quaternary deposits of the Red River and Mekong Plains), unfavorable for the water supply to livelihood and industry. According to the study results in recent years, the groundwater in many densely populated areas contains a high concentration of Arsenic and Ammonia, surpassing many times the maximal permissible concentration by National Standards. The current drinking water guidelines in Viet Nam are set at 10 µg As/L and at 1.5 mg NH4/L. Arsenic and Nitrogen contamination in groundwater in Red River Delta and Mekong River Delta is very severe due to anthropogenic and geogenic sources (Postma et al., 2012; Jenny et al., 2008). Some areas in Red River Delta and Mekong Delta, Arsenic concentration ranges from 27-264 µg/L. Groundwater heavy metal contamination is due to industrial activities and handicraft villages while pesticide and fertilizer contamination in groundwater is due to agricultural activities in rural area (Water Sector Review, 2017)

In Ha Noi, where the groundwater is most strongly withdrawn, there have been formed large cones of depression around pumped wells of some tens of meters deep (Phap Van, Ha Dinh, Mai Dich, etc. wellfields), that causes the land subsidence with the rate of some centimes and more by year.

Excessive groundwater pumping makes groundwater level decrease and consequently land subsidence. In Ha Noi and Mekong River Delta, this issue is happening at different level impacts. In inner Ha Noi area, there are 12 water plants with the total of 200 pumping wells. Total groundwater extraction flow is about 580,000 m3/day. Since 1991, 10 land subsidence monitoring stations have been built by Ha Noi Institute of Technology and Economics of Construction. Land subsidence speed is high in some areas such as Thanh Cong


(41.02 mm/year), Ngo Si Lien (27.14 mm/year), Phap Van (22.02 mm/year), and low in some others such as Ngoc Ha (1.80 mm/year), Mai Dich (2.28 mm/year), Dong Anh (1.41 mm/year). In Ha Noi by InSAR analysis, land subsidence was from 30 cm to 80 cm (Tran et al., 2016). In Ca Mau peninsula, up to 2008, groundwater level has dropped from 10 m to 20 m. Land subsidence analysis showed that total subsidence might reach up 30-80 cm by the end of 2012 and the rate ranges from 3-7 cm/year (Karlsrud et al., 2016).

Viet Nam is considered as one of countries most affected by climate change and sea level rise. As a prediction (IMHEN, 2016) with a scenario of high emission (A1F1), sea level will rise up to 100 cm by the end of the year 2100. Extreme climate and sea level rise have been impacting salinization phenomena in coastal aquifers. Beside it, groundwater extraction although is in limited capacity, but in many places, it has been causing negative impacts, such as excessive lowering of water level, degradation of well discharge and consequently causes the saltwater intrusion in coastal aquifers. This impact is severe now in many coastal aquifers in Red river delta, Mekong River Delta and along the coastal line (Pham, 2017).5. Conclusions

Over the past five decades of investigation, study and development on groundwater resources in Viet Nam, 26 water-bearing units in 7 regions have been identified. Characteristics of water-bearing units were also determined with different level. Some aquifers are very productive such as Pleistocene aquifers in the Red River Delta plain, Basaltic aquifer in the Central High land, Karstic aquifers in the North East and North West, Pleistocene and Neogene aquifers in the Southern plain. Groundwater resources are

represented by potential reserves, classified by hydrogeological region. The total groundwater potential reserves in the country reach nearly 133 million m3/day, which is 48.5 billion m3/year. Groundwater resources are abstracted for many purposes such as drinking, manufacturing, irrigating and aquacultural cultivating especially in Red river plain, in Southern plain and in Central Highlands.

During groundwater abstraction, some challenges have been recognized such as groundwater contaminations of Nitrogen, Arsenic, etc. land subsidence in intensive pumping areas for example in Ha Noi, Ho Chi Minh City, Ca Mau Peninsula; groundwater salinization in coastal aquifers where there is about 3,260 km coastal line with developing areas and impacts from climate change and sea level rise. Some areas in Red River Delta and Mekong Delta, arsenic concentration ranges from 27-264 µg/L, which is over current drinking water standard in Viet Nam at 10 µg As/L. In Ha Noi by InSAR analysis, land subsidence was from 30 cm to 80 cm. In Ca Mau Peninsula, up to 2008, groundwater level has dropped from 10 m to 20 m. Land subsidence analysis showed that total subsidence might reach up 30-80 cm by the end of 2012 and the rate ranges from 3-7 cm/year. There is also severe salinization now in many coastal aquifers in Red river delta, Mekong River Delta and along the coastal line.

Acknowledgements: This paper has been supported by the Korean International Cooperation Agency (KOICA) project as part of the development of human resource for Climate change and Sustainable through active education and training. We would like to express our gratitude to the team from Yonsei University, Korea for encouragement during preparation of this manuscript.

References1. Brown, K. and Root Pty Ltd (2009), Socialist Republic of Viet Nam: Water Sector Review, Asian

Development Bank.2. Jenny, N., Sparrenbom, C. J., Berg, M., Dang, D.N., Pham, Q.N., Sigvardsson, E., Baric, D.,

Moreskog, J., Harms-Ringdahl, P., Nguyen, V.H., Rosqvist, H. and Jacks, G. (2008), “Arsenic mobilisation in a new well-field for drinking water production along the Red River, Nam Du,


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Ha Noi”, Applied Geochemistry, (23), 3127-3142.3. Karlsrud, K. and Tunbridge, L. (2016), Study on land subsidence in Ca Mau province, Viet Nam,

Unpublished report.4. Postma, D., Larsen, F., Nguyen, T.T., Pham, T.K.T., Jakobsen, R., Pham, Q.N., Tran, V.L., Pham,H.V.

andMurray, A.S. (2012), “Groundwater arsenic concentrations in Viet Nam controlled by sediment age”, Nature Geoscience, (5), 656-661.

5. Pham, Q.N., Doan, V.C., Vo, C.N. and Do, T.H. (2013), “Groundwater potential resource of Viet Nam territory”, Journal of Geology, (336-337), 116-124.

6. Tran, Q.C. and Pham, Q.N. (2016), Reviewing theories and developing methods to forecast land subsidence in Ha Noi by radar interferometry method, The Ministry of Science and Technology, Viet Nam.

7. Vu, N.K. et al. (1988), Report on Groundwater resources in Viet Nam, The Ministry of Science and Technology, Viet Nam.


WATER RESOURCE SECURITY

IN THE CONTEXT OF CLIMATE CHANGE IN VIET NAM

Ta Dinh Thi, Ta Van Trung, Bui Duc HieuMinistry of Natural Resources and Environment


Abstract: Nowadays, there is an alarming fact about the shortage of national water resource which is not known by the public. According to statistics, with the population of about 95 million, on average each Vietnamese can receive only 3,200 m3/person/year from the internal water source. On the other hand, the assessment criteria of the International Association of Water Resource indicates that if a country cannot reach 4,000 m3/person/year, it is regarded as a water shortage country.

Both international and national studies have indicated that water resource security is a form of non-traditional security with a close connection with economic security, food security and poverty. If this is not properly solved, it will lead to social insecurity, poverty increase, and even conflicts that have a remarkable impact on national security.

Viet Nam is one of the countries that are most severely affected by climate change. With the global impact of climate change, many issues about water resources in Viet Nam, which used to be a potential threat, have now become a reality.

Keywords: climate change, water resource security, national security.

1. Water resource security and its connection with national security

National security is a political - legal concept that shows the social nature of a country. In spite of having different definitions among nations, the basic idea of national security is generally protecting national interests and eliminating threats to those benefits. National security consists of traditional and non-traditional items. Depending on the context and time, it is threatened by traditional and non-traditional challenges. In Viet Nam, the National Security Law 2004 [3] states that “National security is the stability and sustainable development of Socialist Republic and the Socialist Republic of Viet Nam, the inviolability of independence, the affirmation of sovereignty and unity, territorial integrity in the country”; “Threats to national security are internal and external factors that can probably do harm to the national security of the Socialist Republic of Viet Nam”.

From the cold war to the present, the reality is that the existence of institutions and national regimes is not only dependent on traditional military security elements. Non-traditional factors such as economic recession, public debt, terrorism, environmental pollution, poverty, etc. can cause a nation or a social system to collapse without any military acts.

In the context of drought, salinity intrusion, and floods becoming increasingly severe as a consequence of global climate, water security is now considered one of the issues that can seriously affect national security in the world as well as in Viet Nam.

As one of the leading environmental protection movement agencies in the world, since 1994, the US government has also acknowledged that “water resources, once unchecked, can become the cause of any disasters that can be threatening to the stability of the regions and the world” [6].

According to statistics, 70% of the Earth’s surface is water, but only 2.5% is fresh water, 97.5% is sea water, which is not suitable for

Correspondence to: Ta Dinh ThiE-mail: [email protected]

human consumption and most fresh water, about 68.7%, is in the form of ice [6]. Water shortages currently affect more than 40% of the world’s population, with 783 million of the planet’s population having no access to clean water. A joint report by UNICEF and WHO also found that three out of every 10 people (2.1 billion people on Earth) lack access to safe water in their homes. At the same time, six out of 10 people (equivalent to 4.5 billion people in the world) lack safe sanitation services [10]. With increasing demand for water, by the middle of the twenty-first century, the number of people living with chronic water shortages will have increased steadily in excess of 4 billions [9].

In 2015 only, more than 3 million people worldwide died of diarrhea and water-related diseases. More than 800,000 of these were children. The major causes of death were lacks of clean water and proper sanitation. Most of the world’s rivers are polluted and unsuitable for human use, hindering the lives of billions of dependent people as well as rivers and streams which are used for water supply and livelihoods, and these are also threats to plant and animal ecosystems. This is not just a matter of water, but a threat to human security. In most arid and semi-arid regions, the exploitation of water from groundwater and river systems is occurring at an unsustainable rate, affecting future food production and being an obstruction to socio-economic development [8].

Clean water is expected to soon become a valuable resource no less than oil. However, oil can be replaced with other fuels but water cannot. Many researchers have argued that water conflicts are likely to cause future wars, especially in Asia, North Africa and the Middle East.

In fact, the past period has shown that tension, political instability among countries in the world on water security is always present, and water conflict is always stressful. This can become a political problem that can escalate into a threat to the peace and stability of the world and its regions.

Typical examples are as followed: the conflict in the Middle East between Egypt and Ethiopia; Water Security Crisis in 1990 between Turkey,

Iraq and Syria on the Euphrates River Benefit Sharing; tension between Israel and Palestine on the Jordan River Sharing; tension between Israel and Lebanon on the fresh water of the Litani River flow between the two countries’ borders; conflict in sharing of water interests between India and Bangladesh on embankment projects on the Ganges; water on the border between the United States and Mexico; and the benefits of the Mekong River between China and downstream countries including Thailand, Laos, Cambodia and Viet Nam.

According to statistics, agricultural production is based primarily on water resources and is the largest source of water consumption in economic sectors. In most parts of the world, more than 70% of fresh water is used for agriculture. By the year 2050, an estimated population of 9 billion would require a 50% increase in agricultural production and a 15% increase in water availability [12]. This means that insecurity of water sources also means that economic security and food security will be affected [12].

The concept of “water war” is a new concept recently introduced by international scholars [10, 11]. Although it is merely a statement and a warning, it shows the concern of the international community on this issue is increasing. In the context of global climate change today, the issue of ensuring water security is more urgent than ever.2. Viet Nam’s current water resource security reality and challenges

According to a report by the Ministry of Natural Resources and Environment, Viet Nam has more than 2,360 rivers with a length of 10 kilometers or more, including 108 main rivers. The annual flow water in the territory of Viet Nam is about 830 billion m3. However, most of Viet Nam’s current water source comes from the upstream countries. The total area of river basins in the country is up to 1,167,000 km2, of which the catchment area outside the territory accounts for 72%. Internal surface water volume is only 310 billion m3 (37%), 520 billion m3 (63%) comes from neighboring countries such as China, Thailand, Laos, Myanmar and Cambodia. Water that come from the upstream

JOURNAL OF CLIMATE CHANGE SCIENCENO.3 - 2017

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countries in the Red River Basin accounts for 50%, while the Mekong River Basin accounts for 95% [5, 13].

Due to its geographic location and typical natural conditions, nearly 57% of the country’s total water amount is in the Mekong River Basin, 16% in the Red - Thai Binh River Basin, about 4% in Dong Nai River Basin. For other large river basins, the total water only occupy the remaining part. In addition, Viet Nam’s total rainfall is high but unevenly distributed both in time and space, affecting the reserves and distribution of water resources, causing frequent floods and droughts in a long time [5].

In the Mekong River Basin, hydropower dams, water transfer constructions which have been and will be constructed in the upstream countries will be a major threat to water resources, fisheries resources, silt and sediment, ecosystems,... of Viet Nam. The dams will prevent the transport of silt and sediment, altering the hydrological regime that damages agriculture and downstream fisheries, particularly in the Mekong Delta. In addition, water diversions during the dry season will cause serious shortage of water in the Delta. This is a worrying sign for the 20 million people here, especially affecting the livelihoods of riverine households, who get the main source of income from natural resources and agriculture. In the dry season of 2016, due to the impact of the El Nino, the Mekong River water level was at a recorded low rank in the last 100 years, causing severe droughts and saltwater intrusion in the Mekong Delta.

In addition, the Red River from the downstream has shown signs of pollution, while measures to tackle environmental pollution across borders are limited. The upstream area has operated dozens of hydroelectric power plants, 1,870 dams and canals, and 9 reservoirs with a total capacity of 200 million cubic meters, resulting in significant changes in flow regime, water quality, and sedimentation downstream. In particular, the northern mountainous provinces are vulnerable to floods by hydroelectric power plants water release and environmental pollution activities from the upstream.

Water security is highly dependent on the exploitation and use for socio-economic

development. Although Viet Nam has joined bilateral and multilateral cooperation mechanisms for sustainable water resources development, it is a downstream country that has little advantage in international water use negotiations, the reality is still putting pressure on Viet Nam today to negotiate and share benefits with the upstream countries.

The conflicts are not only in water disputes with neighboring countries. The phenomenon of water disputes within the provinces and localities in Viet Nam is also increasing. To manage and use water for industrial production (factories, hydroelectric power plants, industrial parks,...) unreasonably, ineffectively has caused waste and conflicts of interests as well as environmental impacts. The development of hydropower projects in recent years has shown limited shortcomings in sharing water resources. Water resources on rivers have been largely used for hydropower, which has a major impact on downstream areas. In recent years there have been many water disputes between localities, between units in the same locality, between localities and hydropower plants,... For example, the water disputes between Da Nang and Quang Nam, the water release of Ho Ho hydropower plant (Quang Binh), Bac Ha hydropower plant (Lao Cai), Huong Dien hydropower plant (Thua Thien - Hue),... have negative impacts on the local lowland and adjacent areas.

Most people in Viet Nam nowadays think that Viet Nam’s water resources are plentiful, but Figures have shown that with the current population, the average Vietnamese per capita receives only over 3,000 m3 per person per year from the endogenous source of water, while according to the International Water Resources Association, a country is considered to be deprived of water if it does not reach 4,000 m3/person/year. Viet Nam is one of the countries which is most severely affected by climate change, and these adverse impacts will increase to a higher level of alertness. Many of the problems of water resources are only present in the form of hazards, which are becoming more real.

Climate change is not only a warning but also an increasing presence of Viet Nam’s water


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resources. In fact, in the recent period, due to abnormal weather conditions, frequent water source droughts and droughts of saline water intrusion occurred in the 13 provinces of the Mekong Delta in 2016, which is considered the most severe drought in 100 years in Viet Nam. It is estimated that about 160,000 hectares of rice were damaged and approximately 800,000 tons of rice were lost during the drought and salt intrusion. In the Central Highlands, water in lakes, ponds, and many irrigation constructions were drying out, which cost hundreds of billions of VND for agriculture in this area. Meanwhile, two floods in late November and mid-December in 2016 in the central provinces and Central Highlands caused losses of about 2,600 billion VND. According to the General Statistics Office of Viet Nam, the total value of losses caused by natural disasters in 2016 is estimated at over 18 trillion VND [1].

Water is an indispensable demand for agricultural production. Viet Nam is an agricultural country with a population of 60.58 million people, accounting for 66.06% of the total population of the country, with 30.9% of agricultural land, and 17-19% of GDP of the country [1]. The issue of agriculture, rural areas and farmers is of special importance in building, developing and defending the country and ensuring national food security in Viet Nam. Viet Nam is always in the top group of rice exporters in the world, with a market share of nearly 20% globally. However, despite Viet Nam’s surplus of rice for export, the food security index stands behind most importing countries such as Singapore, Malaysia and Brunei [8]. This shows that our food security is only at the national level (on a per capita basis) but not on household food security.

According to the General Statistics Office, by mid-century, Viet Nam’s population was estimated at 108.7 million and 119.8 million (by high fertility and low fertility level), which is higher from 1.1 to 1.3% compared to today’s demand of 95 million population [4]. Failure in water security also means not only affecting the production and livelihoods of tens of millions of farmers but also affecting the food security of the country. Having the advantage of being one of the leading rice exporters in the world,

it is possible that in the future, Viet Nam’s food security will be guaranteed. However, without proper policies and sanctions and sharing interests among nations, in the future when the upstream countries continue to build dams, hydropower projects, transfer water inside and outside the basin, not only water security, economic security, food security of Viet Nam will be affected.

In addition, in Viet Nam, the majority of the poor lives in mountainous and rural areas and their livelihoods largely depend on agricultural production. Unsecured water security means that agricultural production is suffering from high food prices. The poor will have more difficulty accessing food. According to a World Bank report, the rise in food prices is also directly related to the incidence of poverty, if food prices rise by 10% in Viet Nam, the corresponding poverty rate increases by 0.29% [2]. Hence, water security is one of the causes of poverty in Viet Nam.

It is recognized that water security, if not guaranteed, will have a significant impact on poverty reduction, socio-economic development, food security, economic security and national security of Viet Nam.3. Some proposed solutions to protect water resource in Viet Nam

Water security is one of the non-traditional security issues that are pressing for urgent actions in Viet Nam. Water insecurity can undermine the economy, affect food security, increase poverty, and increase political instability.

From the viewpoint that water security is part of national security, we can see that ensuring the security of water resources must be parallel in many aspects: ensuring the reserve, quality and accessibility of water resources and respond effectively to climate change. Within the framework of this research, some solutions are proposed as follows:

Firstly, continuing implementing the contents of national strategies and programs on climate change, international conventions and agreements that Viet Nam has joined to mitigate climate change, one of the main causes


threatening water security in Viet Nam.Secondly, developing a Set of Criteria and

the Water Resources Security Indicators in line with the conditions in Viet Nam in order to assist the management and policy making. This tool provides information to managers and policymakers to assess and control the level of water security in our country and manage risk effectively. It is also encouraged to formulate and complete the system of policies, solutions and mechanisms for the prevention, response and assurance of water source security in Viet Nam; to develop and issue water resources planning in major national river basins soon. This is an urgent requirement for effective water resource management, which contributes significantly to sustainable development.

Thirdly, paying attention to the application of advanced science and technology to economical use of water resources in all fields, treatment of environmental pollution, disaster recovery and response to climate change. At the same time, it is necessary to research and develop alternative clean energy such as nuclear power, wind power, solar energy,... to ensure energy security, reduce energy pressure from hydropower.

Fourthly, enhancing the capacity of the economy to increase resilience to climate change and decrease water resources through the reform of growth models, the effective use of natural resources, towards green growth, green investment; restructuring the economy, selecting suitable industries to focus on development in the context of climate change.

Fifthly, stepping up the propagation, dissemination and education of the law on protection of water source security in order to raise the awareness of water source protection for organizations and individuals throughout the country.

Sixthly, building up and completing the system of information and databases on water resources, the environment and climate change; strengthening the monitoring, forecasting, warning practice of drought, salt water intrusion and cross-border water pollution, lowering the underground water level; actively researching and applying technical solutions to adapt to climate change and reduce water resources, including

seasonal adjustment, adjustment of production sites, research and application of resistant rice varieties to apply appropriate farming systems (rotational cultivation, multi-cropping, intercropping) to reduce risks as well as exploit natural advantages.

Seventhly, implementing production planning and rearrangement of residential clusters under climate change scenarios; investing in the development of protection forest systems and infrastructure, especially irrigation and roads, in response to climate change; reviewing irrigation, agriculture, aquaculture, forestry and daily-life water supply planning,... in response to extreme weather and subsidence and erosion; collaborating with relevant sectors to develop a plan for water resources management; establishing areas for protection against floods, erosion and salinity intrusion in order to take initiative in transferring flood water into field improvement and aquaculture, creating safe lands for floods and erosion; and actively controlling water resources for agricultural production and rural industrialization.

Eighthly, planning, building and perfecting the system of fresh water reservoirs in the delta; building and strengthening the system of sea dykes and river dykes to combat erosion and salt intrusion; strengthening coastal wave breaking forests, building breakwaters, embankments,... to limit erosion, land subsidence; investing in infrastructure and environmental protection in the mountainous, rural and coastal areas where most poor people are concentrated, and are most vulnerable to the impacts of climate change and sea level rise; strengthening hygiene and epidemiological measures to protect the health of the people to ensure that the poor have access to clean water.

Ninthly, intensifying the inspection, examination and strict control of the activities of changing the flow, dredging the canals, exploiting sand and gravel to cause landslide, adversely affecting the basin environment, affecting to production and livelihood of the people; inspecting, examining and handling violations of water source-polluting activities; investigating, evaluating and classifying waste


23

sources nationwide; establishing a national database on waste sources.

Next, establishing a financial mechanism to support water security activities. On July 7, 1977, the world’s leading experts on water resources led by Professor Quentin Grafton, Australian National University, initiated a charter proposing the establishment of a Global Human Water Security Fund (https://genevaactions.org). This fund is called upon to address three issues: (i) Ensure the provision of services for essential water needs, (ii) Ensure improved water quality in watersheds, rivers and streams and groundwater and (iii) Ensure enhanced management, management and planning of water. Given the challenges and experience in dealing with water security issues, Viet Nam should be a pioneer in the idea of setting up the Fund, along with other developing countries calling for the establishment of the Fund with the support from developed countries which are interested in suporting water resources such as the Netherlands, Australia, Japan, Korea and Germany. It

is possible to select the Mekong Delta as the demonstration site for the Fund’s support activities. In addition, Viet Nam should also preside over the establishment of the Fund in other multilateral cooperation frameworks such as the Australia-ASEAN Summit. This not only helps create resources for water resources security but also enhances Viet Nam’s position in the world, contributing to strengthening national security.

Last but not least, promoting international cooperation on responding to climate change, continuing to strengthen international cooperation with countries in the Mekong River Commission and China to share the common interest in the development and common prosperity of the whole region under the 1995 Mekong Agreement and the newly established Mekong - Lan Tong cooperation channel; cooperating bilaterally and multilaterally to monitor and supervise upstream development activities.

References1. FAO (2015), Regional Overview of Food Insecurity Asia and the Pacific, Bangkok. 2. Geneva Actions on Human Water Security, retrieved on 13 September 2017 at https://genevaac-

tions.org.3. GSO (2011), Viet Nam Population Projection 2009-2049, Publishing House of Statistics. Ha Noi (In

Vietnamese).4. GSO (2016), Social - Economic Status in 2016 (In Vietnamese).5. MONRE (2016), Environmental Status Report 2011-2015, Viet Nam Publishing House of Natural

Resources, Environment and Cartography, Ha Noi (In Vietnamese).6. Shiklomanov, A.I. (1999), World water resources and water use: Modern assessments and outlook

for the 21st century.7. Starr, J.R. (1991), “Water wars”, Foreign policy, (82), 17-36.8. The White House (1994), A national security strategy of engagement and enlargement, U.S.

Government Printing Office, Washington DC. 9. The 2030 water resources group (2016), Partnerships for transformation, 2030 water resources

group report 2016.10. Shiva, V. (2016), Water wars: Privatization, Pollution, and Profit, North Atlantic Books.11. Viet Nam National Assembly (2004), Law on National Security (In Vietnamese).12. WHO & UNICEF (2017), 2017 Update and SDG Baselines, Progress on Drinking Water, Sanitation

and Hygiene.13. WB (2015), Shock Waves, Managing the Impacts of Climate Change on Poverty, Climate Change

and Development Series.


ASSESSMENT OF DROUGHT CONDITIONS IN THE RED RIVER DELTA

Nguyen Van Thang, Mai Van Khiem, Truong Thi Thanh Thuy, Ha Truong Minh, Pham Thi Hai Yen, Nguyen Dang Mau

Viet Nam Institute of Meteorology, Hydrology and Climate Change


Abstract: The standardized precipitation index (SPI) is used to analyse drought conditions in the past 54 years (1961-2014) and to assess possible drought conditions in the 21st century under the RCP4.5 and RCP8.5 scenarios for the Red River Delta. The results show that with different timescales, the drought conditions of the Red River Delta tended to increase during the period of 1961-2014. Compared to the baseline period (1986-2005), the number of drought spells are likely to decrease in the future under both scenarios. The projected drought changes of the 1-, 3-month timescales are smaller than those of the 6-, 12-month timescales. Remarkably, the drought intensity of 1-, 3-month timescales is likely to be more extreme by the end-21st century under both RCP4.5 and RCP8.5.

Keywords: SPI, drought, Red River Delta.

1. IntroductionDrought is one of the most common

natural disasters in Viet Nam that seriously affects environment, economy, society and human health. According to the World Meteorological Organization, drought can be classified into four groups: meteorological, hydrological, agricultural and socio-economic drought [15]. Unlike other types of natural disasters, the effects of drought often accumulate slowly over a considerable period of time and may last for years after the termination of the drought event. As a result, the meteorological drought often occurs firstly, followed by agricultural and hydrological droughts. Recently, due to the effects of climate change, droughts have increased in intensity and frequency, significantly affecting agriculture, forestry, industry, water resources, hydroelectric power generation, natural environment and human life, etc. in the country’s regions. In particular, the Red River delta and the Mekong River Delta are two regions affected most seriously. Therefore, drought studies are of interest for researchers, policy makers and localities.

The Red River Delta has the highest population density, is the political, economic and cultural center, and is one of the two biggest food resources in Viet Nam. Since 1993, droughts have been continuously occurring on a large scale in this region owing to the depletion of water resource due to increasing demand for water for daily life and agricultural production [6]. Therefore, drought studies in this region to predict future drought are essential to minimize risks and damages coursed by drought. In the Red River Delta, the frequency of drought is quite high in the winter months, early spring (November, January, March) and very low in the summer and autumn months. The main cause of drought in this region is the deficit of precipitation and flows, especially extreme droughts become very severe during El Niño events.

From what have mentioned above, the study focuses on analysing and evaluating past trends and projecting future changes in drought conditions for the Red River Delta based on the latest results of the Ministry of Natural Resources and Environment and the Intergovernmental Panel on Climate Change (IPCC). This study can provide the latest and most important information on drought changes in the future.

Correspondence to: Nguyen Van ThangE-mail: [email protected]


25

There are a number of drought indices that have been applied internationally as well as in Viet Nam to study drought; however, this study uses the standardized precipitation index (SPI). The SPI is a simple and effective index to reflect drought condition. The SPI is based on just one variable (rainfall) and can be calculated for 3-, 6-, 12-, 24-, 48-month timescales; therefore, the researchers, policy makers greatly appreciate for its diversity.2. Data and methodology

2.1. Data(1) Observed data

The daily precipitation data updated to 2014 from 12 observation stations in the Red River Delta have been used in this analysis (Table 1).

(2) Model dataThe daily precipitation data of PRECIS model

during reference period (1986-2005) and future projections (2016-2035, 2046-2065, 2080-2099) under RCP4.5 and RCP8.5 scenarios were used for calculation. For the study purposes, quantile mapping correction method was chosen to correct the bias of PRECIS model simulations in comparison with the observational data.

Table 1. Observed stations of the Red River Delta during 1961-2014

Order Stations Longitude Latitude Data period 1 BA VI 105.40 21.08 1969 - 20142 HA DONG 105.77 20.97 1973 - 20143 SON TAY 105.50 21.13 1961 - 20144 HA NOI 105.85 21.02 1961 - 20145 CHI LINH 106.38 21.10 1961 - 20146 HAI DUONG 106.30 20.95 1961 - 20147 HUNG YEN 106.05 20.67 1961 - 20148 NAM DINH 106.17 20.43 1961 - 20149 VAN LY 106.30 20.12 1961 - 2014

10 THAI BINH 106.35 20.45 1961 - 201411 NINH BINH 105.98 20.27 1961 - 201412 NHO QUAN 105.73 20.32 1961 - 2014

2.2. MethodologyThe standardized precipitation index (SPI) is

used for assessing drought conditions of the Red River Delta. The SPI is a widely used drought index and was developed by McKee et al. (1993) [5]. According to McKee et al. (1993), the SPI was defined on each of the time scales as the difference of precipitation (R) from mean value ( ) for a specified time period and then divided by the standard deviation (σ ) where the mean value is determined, i.e.

R RSPIσ−

= (1)

The SPI is a dimensionless index. The SPI was designed to quantify the precipitation deficit for different timescales which depends on the study purpose, for example a 1- or 2-month SPI for meteorological drought, from 1-month to 6-month SPI for agricultural drought, and 6-month up to 24-month SPI or more for hydrological drought analyses and applications [12]. Positive SPI values indicate that precipitation is greater than median precipitation, and negative values indicate that precipitation is less than median precipitation, i.e. it indicates dry and wet conditions respectively. The larger the negative values of SPI are, the more severe the drought is. Drought state ends when the SPI

R


values are positive. Extreme drought conditions of the Red River Delta are defined as the minimum SPI values (MIN_SPI) in the dry season.

In this study, the SPI and MIN_SPI are calculated for timescales including 1-month (SPI1, MIN_SPI1), 3-month (SPI3, MIN_SPI3), 6-month (SPI6, MIN_SPI6) and 12-month (SPI12, MIN_SPI12).

Projected changes under RCP4.5 and RCP8.5 scenarios:

Projected changes in the SPI (%) under RCP4.5 and RCP8.5 scenarios in the future (2016-2035, 2046-2065, 2080-2099) compared to the baseline period (1986-2005) is computed as follow:

Where: is the difference between

SPI in the future and SPI in the baseline period (%). SPI*future and SPI*1986-2005 are the mean SPI values in the future periods and the baseline period respectively.

3. Results and discussion

3.1. Trends of drought in the pastFigure 1 shows observed trends in the dry

season SPI index in the Red River Delta at the 1-, 3-, 6-, 12-month timescales between 1961 and 2014. In general, the SPI tended to decrease by 0.02-0.08 unit per decade at the 1-month timescale, above 0.08 unit per decade at the 3-, 6-, 12-month timescales. Therefore, the drought condition in the Red River Delta tended to increase during the period of 1961-2014 with the most obvious trends at the 3-month and 6-month timescales.

The extreme drought conditions also had increasing trends in most areas at the 1-, 12-month timescales, and over the entire Red River Delta at the 3-, 6-month timescales (Figure 2). To specific, the MIN_SPI shows upward trends during 1961-2014 with the rate of the MIN_SPI increase at the 3-, 6-month timescales being faster than that at the 1-, 12-month timescales.

Figure 1. Observed trends of SPI index for 1-, 3-, 6-, 12-month timescales:(a) 1-month, (b) 3-month, (c) 6-month, (d) 12-month

(a) (c)(b) (d)

Figure 2. Observed trends of MIN_SPI index for different timescales: (a) 1- month, (b) 3-month, (c) 6-month, (d) 12-month

(a) (c)(b) (d)

1986 2005

1986 2005

( )*100f utureSPI SPI

SPISPI

−

−

−∆ =

f utureSPI∆

(2)


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3.2. Future changes in drought condition

3.2.1. The beginning of the 21st century (2016-2035)

Under RCP4.5 and RCP8.5, at the beginning of the 21st century, the drought conditions of the Red River Delta in dry season are likely to

decrease relative to the baseline period (1986-2005). Figure 3 shows that compared with the baseline period, dry season SPI is projected to increase by 0 to above 0.8% at the beginning of the 21st century with the projected changes of SPI1 and SPI3 being smaller than those of SPI6 and SPI12.

However, under both scenarios, at the beginning of the 21st century, compared to the baseline period, extreme drought condition is likely to increase in the Red River Delta at the 1-month timescale (i.e. the MIN_SPI1 is projected to decline) and decrease in this region at the 6-, 12-month timescales (i.e. MIN_SPI6 and MIN_SPI12 are projected to rise) (Figure 4). For the 3-month timescale, compared to the baseline period, extreme drought conditions are projected to be different between RCP4.5 and RCP8.5 scenarios. Extreme drought conditions of the 3-month timescale are likely to decline in most of the region under RCP4.5 scenario and rise over the entire region under RCP8.5 scenario.3.2.2. The middle of the 21st century (2046-2065)

In the middle of the 21st century (2046-

2065), projected changes in SPI under both scenarios are quite similar. The SPI is projected to slightly increase by 0-0.6% at the 1-, 3-month timescales and 0.6 to more than 0.8% at 6-, 12-month timescales (Figure 5). This indicates that by the middle of the 21st century, the drought conditions of the Red River Delta are likely to decline compared to the baseline period. In comparison with the baseline period, the extreme drought conditions of the Red River Delta by the middle of the 21st century are likely to decrease under both scenarios at the 6-, 12-month timescales, but projected changes are different between RCP4.5 and RCP8.5 scenarios at the shorter-time scales (Figure 6). For the 1-, 3-month timescales, extreme drought conditions are projected to decrease under RCP4.5 scenario (i.e. the

(a) (c)(b) (d)

Figure 3. Percentage changes (%) of dry season SPI for 2016-2035 average relative to 1986-2005 average under RCP4.5 and RCP8.5 for timescales: 1-month (a, e), 3-month (b, f), 6-month (c, g),

12-month (d, h)

(e) (g)(f) (h)


projected MIN_SPI is rise and increase in most of the region under RCP8.5 scenario (i.e. the projected MIN_SPI is decline).3.2.3. The end of the 21st century (2080-2099)

Similar to the mid-21st century, projected changes in SPI under both scenarios by the end of the 21st century (2080-2099) are quite similar. The SPI is projected to slightly increase by 0-0.4% at the 1-month timescale, 0.2-0.6% at the 3-month timescale and 0.6% to more than 0.8% at 6-, 12-month timescales (Figure 7). In other words, by the end of the 21st century, compared to the baseline period, the drought conditions are likely to decrease in the Red River Delta where projected changes of the 1-, 3-month time scales are smaller than those of the 6-, 12-month time scales.

Under RCP4.5 and RCP8.5 scenarios, by the end of the 21st century, extreme drought conditions are likely to increase in the Red River Delta at the 1-month timescale and decrease in this region at the 6-, 12-month timescales. Figure 8 show that the MIN_SPI is projected to decrease by 0-0.2% at the 1-month timescale, increase by 0.2-0.6% at the 6-month timescale and 0.6% to above 0.8% at the 12-month timescale. For 3-month timescale, compared to the baseline period, extreme drought conditions are likely to decrease in the Red River Delta. The MIN_SPI3 is projected to decrease by 0-0.2% in much of the region under RCP4.5 scenario and over the entire region under RCP8.5 scenario by the end of the 21st century.

(a) (c)(b) (d)

Figure 4. Projected changes in dry season MIN_SPI (%) for 2016-2035 average compared to 1986-2005 average under RCP4.5 and RCP8.5 for timescales: 1-month (a, e), 3-month (b, f),

6-month (c, g), 12-month (d, h)

(e) (g)(f) (h)


29

(a) (c)(b) (d)

Figure 5. Percentage changes (%) of dry season SPI for 2046-2065 average relative to 1986-2005 average under RCP4.5 and RCP8.5 scenarios for timescales: 1-month (a, e), 3-month (b, f), 6-month

(c, g), 12-month (d, h)

(e) (g)(f) (h)

(a) (c)(b) (d)

Figure 6. Dry season MIN_SPI changes (%) for 2046-2065 average relative to 1986-2005 average under RCP4.5 and RCP8.5 scenarios for scales: 1-month (a, e), 3-month (b, f), 6-month (c, g),

12-month (d, h)

(e) (g)(f) (h)


(a) (c)(b) (d)

Figure 7. Projected changes in dry season SPI (%) for 2080-2099 average compared to 1986-2005 average under RCP4.5 and RCP8.5 for timescales: 1-month (a, e), 3-month (b, f), 6-month (c, g),

12-month (d, h)

(e) (g)(f) (h)

(a) (c)(b) (d)

Figure 8. Dry season MIN_SPI changes (%) for 2080-2099 average relative to 1986-2005 average under RCP4.5 and RCP8.5 scenarios for timescales: 1-month (a, e), 3-month (b, f), 6-month (c, g),

12-month (d, h)

(e) (g)(f) (h)


31

References1. IPCC (2007), Climate Change 2007: The Scientific Basis, Contribution of Working Group I to the

Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

2. Ministry of Natural Resources and Environment (2009), Climate change, sea level rise scenarios for Viet Nam, Viet Nam Publish House of Natural Resources, Environment and Cartography, Ha Noi.



5. McKee, T.B., Doesken, N.J. and Kleist, J. (1993), “The relationship of drought frequency and duration to time scales”, Preprints Eighth Conference on Applied Climatology, Anaheim, CA. Am. Meteor. Soc., Boston, 179-184.

6. Nguyen, D.N. (2002), Understanding drought and desertification, Science and Technics Publishing House, Ha Noi, Viet Nam.

7. Nguyen, D.N. and Nguyen, T.H. (1991), Climate change and its impacts on Viet Nam in the past 100 years, Nature and people, National Political - Truth Publishing House, Ha Noi, Viet Nam.

8. Nguyen, D.N. and Nguyen, T.H. (1999), Climate change situations in Viet Nam in the next decades, Viet Nam Institute of Meteorology, Hydrology.

9. Nguyen, V.T. et al. (2010), Study the impacts of climate change on natural conditions, natural resources and propose strategic solutions for prevention, mitigation and adaptation to serve sustainable socio-economic development in Viet Nam, Final Report called KC.08.13 state/06-10. Viet Nam Institute of Meteorology, Hydrology and Environment, Ha Noi, Viet Nam.

10. Nguyen, V.T. et al. (2015), Changes in Climate Extremes and Impacts on the Natural Physical Environment, Viet Nam Publishing House of Natural resources, Environment and Cartography, Ha Noi, Viet Nam.

11. Nguyen, V. T. et al. (2017), “Changes in climate extreme in Viet Nam”, Viet Nam Science and Technology (VISTECH). 1(1), 79-87.

12. WMO (2012), Standardized Precipitation Index, User guide, WMO-No. 1090.13. Truong, D.T., Nguyen, D.M., Mai, V.K., Ha, T.M. and Dao, T.T. (2014), “Drought projections in the

South Central region using the PRECIS model”, Scientific and Technical Hydro - Meteorological Journal, (644).

14. IMHEN (2010), The impacts of climate change on water resources and adaptation solutions in the Red River Delta, Project Final Report.

15. WMO (2005), Drought assessment and forecasting.

4. ConclusionsThis study analyzed the drought conditions of

the Red River Delta in the past 54 years (1961-2014) and assess possible drought conditions in the 21st century under the RCP4.5 and RCP8.5 scenarios. Rainfall data from 12 observed stations of the Red River Delta and SPI index are used for the study purposes. The results of analysis show that in dry season with different time scales, the drought and extreme drought conditions of the Red River Delta had upward trends during 1961-2014. The most obvious

trends were found at the 3-, 6-month time scales. Under RCP4.5 and RCP8.5 scenarios, compared to the baseline period, the drought conditions of the Red River Delta are likely to decrease in the future with projected changes of the 1-, 3-month timescales being smaller than those of the 6-, 12-month timescales. It is worth noting that under both scenarios, extreme drought conditions are projected to increase at the 1-, 3-month timescales and decrease at the 6-, 12-month timescales by the end of the 21st century in comparison with the baseline period.


MULTI-RISK: AN APPROACH FOR DISASTER RISK MANAGEMENT

Huynh Thi Lan Huong, Tran Thanh ThuyViet Nam Institute of Meteorology, Hydrology and Climate Change


Abstract: Natural disaster risk assessment is a critical part of a risk management system. Single risk assessment which addresses different natural hazards and their associated risks separately is a popular one used in risk management in Viet Nam. Single risk assessment deals with only one source of disaster ignoring all the possible risk interactions. A multi-risk approach therefore has currently been developed and tested by a number of scholars. This paper introduces a multi-hazard and multi-risk assessment methodology adopted from literature review, which combines single risk assessment and a three-level risk assessment. Multi-risk approaches takes into account the interactions and relations among hazards and among vulnerabilities. It can bring benefits but also challenges to both end-users and scientists.

Keywords: multi-risk, multi-hazard, disaster risk reduction.

1. IntroductionLocated in the tropical monsoon area, Viet

Nam is one of the most disaster-prone countries in the world. Due to its geographic location and topography such as a long coastline, Viet Nam suffers from multi natural disasters including typhoons, tropical cyclones, tropical storms, floods, droughts, saline water intrusions, landslides and earth quakes. In recent years, in the course of a changing climate, natural disasters in Viet Nam have been increased significantly in terms of magnitude, frequency and volatility. Between 1990 and 2016, natural disasters claimed almost 12,000 lives and caused GDP losses of 1 to 1.5% per year [7, 8]. Therefore, natural disaster risk management including prevention and mitigation require appropriate approaches and methodologies to address these issues.

Single risk approaches deal with only one source of disaster and its relevant vulnerability of exposed elements. Single risk analysis allows to determine the individual risk arising from one particular hazard and process occurring in a specific geographic area during a given period of time, while it does not provide an integrated

assessment of multiple risks triggered by different forces or the cascade effect of natural hazards [4]. However, natural disasters are usually closely linked to each other and cannot fully understand separately. For example: (i) A typhoon causes heavy rain, which triggers floods that can led to secondary landslide and debris flow [2]; (ii) An earthquake may result in a tsunami; (iii) High wind speeds during a tropical typhoon can cause a storm surge etc.

Consequently, multi-risk management should develop a more integrated approach. This is a new concept in risk management for Viet Nam. This paper will present a multi-risk approach that has been currently discussed internationally.2. Multi-hazard and multi-risk concept

2.1. Multi-hazard concept The Sendai Framework for Disaster Risk

Reduction 2015-2030 highlighted that “Disaster risk reduction requires a multi-hazard approach”. However, there is currently no clear definition of multi-hazard provided by the United Nations office for Disaster Risk Reduction (UNISDR). It is suggested that multi-hazard is an approach considering more than one hazard in a given place and the interrelations between these hazards, including their simultaneous or

Correspondence to: Huynh Thi Lan HuongE-mail: [email protected]


33

cumulative occurrence and their potential interactions [2]. The multi-hazard concept is related to the analysis of different relevant hazards, triggering and cascade effects threatening the same exposed elements with or without temporal concurrence. A multi-hazard risk assessment determines the probability whether or not different hazards, as a result of the same triggering event, occur at the same time or shortly following each other without chronological coincidence [2].2.2. Multi-risk concept

Multi-risk concept addresses both a multi-hazard which may consider all the hazards and multi-vulnerability perspectives [3]. The multi-risk concept refers to a complex variety of risk combinations (i.e. various combinations of hazards and vulnerabilities). A multi-risk approach entails a multi hazard and a multi-vulnerability perspective. As mentioned in the above section, the multi-hazard concept may refer to: (i) the fact that different sources of hazard might threaten the same exposed elements (with or without temporal

coincidence); or (ii) one hazardous event can trigger other hazardous events (cascade effects). On the other hand, the multi-vulnerability perspective may refer to: (i) a variety of exposed sensitive targets (e.g. population, infrastructure, cultural heritage, etc.) with possible different vulnerability degree against the various hazards; or (ii) time-dependent vulnerabilities, in which the vulnerability of a specific class of exposed elements may change with time as consequence of different factors (as, for example, the occurrence of other hazardous events, etc.) [1]. Multi-risk assessment is to determine the whole risk from several hazards, taking into account possible hazards and vulnerability interactions. In other words, to understand the multi-risk concept the most two important pillars must be taken into account are multi-hazard and multi-vulnerability in the target area (e.g. administrative unit, case study) [4].

A relationship between multi-hazard and multi-risk could be demonstrated in the Figure 1 below:

Figure 1. From single risk to multi-risk [5]3. Multi-risk assessment methodology

Multi-risk assessment methodology strongly depends on the purpose and scale of the study and the availability of the information and data. It may vary from a simple one such as using a

A single risk assessment considers only one source of hazard that could effect on a target area, multi-hazard risk assessment considers all interaction of risks caused by multi hazards and address all possible impacts on a target area.


simple risk indexes for example potential losses and mortality to a very comprehensive one such as multi-risk models [4]. A new quantitative

methodology for multi-risk assessment which is adopted from literature review is demonstrated in Figure 2 and will be introduced in this section.

The multi-risk assessment consists of following steps: (i) Risk assessment for single hazards; (ii) Level 1: Qualitative multi-risk analysis; (iii) Level 2: Semi-quantitative multi-risk analysis; and (iv)

Level 3: Quantitative multi-risk analysis.In the first step, single risk assessment will be

carried out following the classical approach as demonstrated in Figure 3.

Figure 2. Multi-risk assessment framework [10]

Figure 3. Multi-risk assessment framework [10, 13]

The single risk assessment comprises of the following stages:

- Definition of space/time assessment window (target area, time window) and the risk metric quantifying the expected losses (e.g., economic loss, fatalities, etc.). Depending on the purpose of the end-user, the space and time window is different. For example, if the purpose of using the multi-risk assessment results is to prioritize mitigation actions, a window will be a typical

time frame that can facilitate the comparison e.g. one year; if the purpose is to take mitigation actions during an emergency, real-time forecast for each different risk scenario will be required, then the window may be days or weeks; if the purpose is for land-use planning, a longer time frame of typically decades or centuries will be possible [10, 11].

- Threat(s) identification (e.g., earthquake, volcano, landslide, meteorological events, etc.).


35

- Single hazard assessment (e.g., rate of occurrence, pathway, intensity measure, etc.).

- Assessment of the vulnerability of the elements at risk (receptors, e.g., people, buildings, environment, etc.); and

- Assessment of the consequences in terms of the chosen metric (e.g., loss of life, economic losses, environmental degradation, etc.).

In the level 1 analysis, a list of questions that help to decide whether or not to move to the level 2 analysis will be provided. Each question

will be supplied with an exhaustive list of answers. Depending on individual cases, the questions

will provide multiple choice answers. In case that the level 1 results strongly suggest that a more detail analysis is required, we move to level 2. If cascading events are potentially a concern, we can directly move to level 3 analysis [10].

In the level 2, interactions between hazards and dynamic vulnerabilities are assessed by using a matrix approach as a semi-quantitative method.

As illustrated in the Figure 4 above, in the level 2 we have to create the hazard interaction and vulnerability interaction indexes. In case that these indexes are greater than the correspondent thresholds and resources and required data are available, we will move to the level 3.

In the level 3, interactions among hazards and dynamic vulnerability are assessed quantitatively using the Bayesian network.

A conceptual Bayesian network as shown in Figure 5 is suggested to use for determining the whole risk from several threats. The network takes into account possible hazards and vulnerability interactions that include: (i) hazards that independent but threatening the same elements at risk with or without chronological coincidence; and (ii) hazards that depend on another one or caused by the

Figure 4. Level 2 multi-risk analysis framework [10, 13]

same triggering event or hazard. Besides, the network consists of two main sub-networks for: (i) multi-hazard and (ii) time-dependent vulnerability [10, 11, 13].4. Multi-risk benefits

A multi-risk approach creates results that consider both quantitative assessment of the different risks and the effects of their possible interactions. Therefore, it is found that a multi-risk approach could bring benefits to improve land use planning, response capacity as well as evidence for the identification of priorities for natural disaster mitigation actions [14].

Land use planning will be improved if the multi-risk approach is applied for risk assessment in general and natural disasters in particular. Currently, in Viet Nam maps with the areas vulnerable to flash floods, typhoons, storm-


Figure 5. Bayesian network for quantitative multi-risk assessment [10, 13]

surges etc. are available but they are developed based on the single risk approach, focus on single disaster, neglecting other events occurring at the same time or shortly following. For example, the typhoon zoning as in Figure 6, which illustrates Viet Nam’s exposure to tropical typhoons, heavy rain falls and strong winds [12].

The typhoon zoning is based on three criteria including: (i) Three consecutive peak months in the year; (ii) Annual frequency of storms; and (iii) Rain and strong wind caused by storms. Tropical storm and tropical depression data during 1961-2014 was used for the study. As a results, Viet Nam can be divided into 8 typhoon risk zones. The interaction at both hazard and vulnerability level were not taken into account in the study.

Another example is the natural hazard risks map of Viet Nam developed by the United Nations Office for the Coordination of Humanitarian Affairs. Areas exposed to earthquake and tropical storm are visualized based on the likelihoods of the specified intensities. Earthquake intensity zones indicate where there is a 20% probability that

degrees of intensity shown on the map will be exceeded in 50 years; tropical storm intensity zones indicate where there is a 10% probability of a storm of this intensity striking in the next 10 years [6]. Possible risk of the landslides triggered by earthquake or heavy rains occurring with the tropical storm are not included in the map. Neglecting effects of interactions between hazards could lead to an underestimation of the risk. Therefore, a multi risk approach is highly desirable in land use planning. The adoption of a multi-risk approach could help to support the decisions on a restriction of buildings and other constructions as well as permitting or forbidding construction of new buildings, infrastructures, constructions and economic activities in the risky areas.

Response capacity would substantially benefit from applying a multi-risk approach. A development of multi-risk scenarios to facilitate a respond plan therefore is highly recommended. For instance, the interaction among typhoon, intense rainfall, flash flood and their consequences for infrastructures and the evacuation of injured people to hospitals


37

Figure 6. Typhoon and typhoon risk zoning [9, 12]

or safety places will be addressed in multi-risk scenarios but not in a single disaster one [8]. In the Northern mountainous area in Viet Nam, intense rainfall triggered by a circulation of tropical storm then causing flash flood might cut off the main transportation infrastructure affecting the evacuation of the injured to hospitals. A respond plan adopting a multi-risk approach will provide more accurate time for evacuation of injured either considering or not considering the damage or interruption of transportation network and connectivity to the hospitals [4].

Prioritizing risk mitigation actions based on a single risk approach will neglect the hazards and vulnerability interactions. As a result, identification of priority risk reduction actions using a single risk approach may increase the vulnerability to other hazards.

A multi-risk approach therefore is useful for decision makers in prioritizing the mitigation actions.5. Challenges

Even the advantage of a multi-risk approach is evident, challenges for an effective implementation still remain and can be summarized as follows:

i. The challenge to compare risks caused by different hazards. Each type of risk has its own scale or unit of measurement for quantifying risk or damages, for example, loss ratio for floods and damage state for seismic [14].

ii. A limited understanding of the complex relations and interactions between hazards. This consequently can hamper a multi-risk assessment.

iii. Limited exchange between scientists


and end-users in terms of knowledge transfer particularly at local level [14].

iv. Different interests of end-users and researchers: Researchers are interested to improve knowledge and understanding of physical processes and models especially related to cascade effects; harmonizing terminology and databases; reduce uncertainty of assessments; integrate results of multi-risk assessments into existing emergency scenarios and conduct multi-vulnerability assessments [14]. Meanwhile end users would prioritize collecting evidence about lives and property saved; learning to use and integrate multi-risk assessment results in existing plans.6. Conclusions

The multi-risk approach determines the whole risk from several relevant hazards, taking into account possible hazards and vulnerability relations and interactions. The new multi-hazard and multi-risk assessment method adopted from the literature was introduced, which consists of

risk assessment for single hazards and a three level multi-risk assessment of qualitative, semi-quantitative and quantitative multi-risk analysis. Depending on the purpose and scale of the study and the available of required information and data, the application of the multi-risk assessment approach could be adjusted accordingly. It is found that a multi-risk approach could bring benefits to improve land use planning, response capacity as well as provide more evidences for the identification of priorities for natural disaster mitigation actions. However, this approach comprises challenges such as comparing the risks, limited understand of complex hazard relations and interactions, different views between end-users and researchers etc. Due to the fact that multi risk approaches will consider both hazards and vulnerability interactions, which is neglecting in the single risk approach, it is therefore highly recommended to introduce this approach to the disaster risk reduction community in Viet Nam.

References1. Arisrizabal, A.G. and Marzocchi, W. (2011), State-of-the-art in multi-risk assessment, Deliverable

D5, 1.2. European Commission (2010), Commission staff working paper: Risk assessment and mapping

guidelines for disaster management, Brussels, Belgium.3. Di Mauro, C. et al. (2006), Definition of multi-risk maps at regional level as management tool:

experience gained by civil protection authorities of Pie Monte region, Proceedings of the 5th Conference on Risk Assessment and Management in the Civil and Industrial Settlements. 2006.

4. Gallina, Valentina, et al. (2016), “A review of multi-risk methodologies for natural hazards: Consequences and challenges for a climate change impact assessment”, Journal of environmental management, (168), 123-132.

5. Gasparini, P. and Aristizabal, A.G. (2014), Seismic risk assessment: Cascading effects, Book chapter, in: Encyclopedia of Earthquake Engineering, Section: ‘Seismic risk’ , M. Beer, E. Patelli, I. Kougioum-tzoglou, I. Siu-Kui Au, Eds.

6. http://www.preventionweb.net/english/professional/maps/v.php?id=234697. http://118.70.74.167:8081/DesInventar/profiletab.jsp?countrycode=vnn&continue=y8. IMHEN and UNDP (2015), Viet Nam Special Report on Managing the Risks of Extreme Events and

Disasters to Advance Climate Change Adaptation, [Tran Thuc, Koos Neefjes, Ta Thi Thanh Huong, Nguyen Van Thang, Mai Trong Nhuan, Le Quang Tri, Le Dinh Thanh, Huynh Thi Lan Huong, Vo Thanh Son, Nguyen Thi Hien Thuan, Le Nguyen Tuong], Viet Nam Publishing House of Natural Resources, Environment and Cartography, Ha Noi.

9. IMHEN (2014), Synthesis Report on Storm zoning, storm risk and storm surge determination for coastal areas of Viet Nam (In Vietnamese).

10. Liu, Z., Nadim, F., Aristizabal, A.G., Mignan, A., Fleming, K. and Luna, B. Q. (2015), “A


39

three-level framework for multi-risk assessment”, Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 9(2), 59-74.

11. Marzocchi, W., Aristizabal, A.G., Gasparini, P., Mastellone, M. L. and Di Ruocco, A. (2012), “Basic principles of multi-risk assessment: a case study in Italy”, Natural hazards, 62(2), 551-573.

12. MONRE (2014), Storm zoning, storm risk and storm surge determination for coastal areas of Viet Nam, Issued together with Decision No. 1857 / QD-BTNMT in August 29, 2014 by the Ministry of Natural Resources and Environment (In Vietnamese).

13. Nadim, F., Liu, Z., Aristizabal, A.G., Woo, G., Aspinall, W., Fleming, K. and Van Gelder, P. (2013), Framework for multi-risk assessment, Deliverable D5, 2.

14. Scolobig, Anna, et al. (2014), From multi-risk assessment to multi-risk governance: recommendations for future directions, 163.


IMPACT OF CLIMATE CHANGE ON INTENSITY-DURATION-FREQUENCY CURVES IN HO CHI MINH CITY

Mai Van Khiem, Ha Truong Minh, Luu Nhat LinhViet Nam Institute of Meteorology, Hydrology and Climate Change


Abstract: Viet Nam is considered as one of the countries most affected by climate change. The magnitude and frequency of extreme events (such as high-intensity rainfall, flooding, severe droughts) are expected to increase in future due to climate change. The evaluation of the possible climate change influence on extreme precipitation is very interesting in megacities city due to the usual and characteristic high intensities of its rainfall pattern. This study aims at developing Intensity-Duration-Frequency (IDF) curves for Ho Chi Minh City, Viet Nam for the present as well as future climatic scenarios. The rainfall projections for future periods based on ensemble regional climate modeling approach are used to calculate IDF curves and their plausible changes in the middle of the 21st century (2050s), and at the end of 21st century (2090s). The results suggest that intensities of extreme rainfall events versus various durations with different return periods are all likely to increase over time in comparison with baseline period (1986-2005): [11, 60]% in 2050s, and [15, 69]% in 2090s under most likely case; and [38, 141]% in 2050s, and [28, 105]% in 2090s under high impact case. Such a consistent increase in the exceedance values of rainfall intensity of extreme events, implying that intense rainfall events are likely to occur more frequently in the future under climate change. The results presented in this paper are important for the design and construction of different hydrological structures in water management in Ho Chi Minh City.

Keywords: IDF curve projection, climate change, Ho Chi Minh City.

1. IntroductionThe effects of climate change on hydrology

and the potential intensification of the hydrological cycle have to be considered in order to prevent future problems in the urban drainage systems. The intensity-duration-frequency (IDF) curves, a very important tool used in the design and construction of different hydrological structures in water management, could be altered by a presumed increase of intense rainfall caused by climate change. Therefore, there are many research studies in rainfall IDF for specific regions or provinces not only in developed countries but also in many developing countries. De Paola et al. (2014) estimated the rainfall IDF for three cities, including Addis Ababa (Ethiopia), Dar Es Salaam (Tanzania) and Douala (Cameroon), using rainfall observations and rainfall

estimates derived from the CMCC model. The temporal disaggregation method was used to obtain the rainfall amounts over smaller time scale. The evaluation of rainfall IDF was conducted, and then the projection of rainfall IDF was estimated to verify the change of extreme values under climate change. Akpan and Okoro (2013) developed two sets of rainfall IDF models for Calabar City (Nigeria), and estimated the relationship between rainfall intensity and duration for specific frequencies and associated rainfall intensity and frequency for specific durations, using a rainfall dataset from 2000 to 2009. These models are used to predict the possibility of a certain amount of rainfall that may be used in planning and designing the infrastructure in Nigeria. Logah et al. (2013) analyzed rainfall data of four stations in Greater Accra Region to develop the rainfall intensity - duration - frequency curves by fitting the rainfall intensity to Gumbel distribution for

Correspondence to: Mai Van KhiemE-mail: [email protected]


41

various durations. Le et al. (2006) used four empirical functions including the Talbot, Bernard, Kimijima and Sherman equations to construct rainfall IDFs for several stations in Viet Nam. Their study compared the results among these four methods and then chose the appropriate equation for Viet Nam. In addition, this study also proposed a method to generalize the IDF curve for ungauged rainfall locations over Viet Nam. Nguyen et al. (2007) constructed rainfall IDFs using temporally and spatially downscaled rainfall data under the A2 scenario. The SDSM method combined with bias correction is employed to obtain adjusted daily rainfall estimates at several rain gauge stations in Quebec. After that, the scaling General Extreme Value (GEV) distribution produces sub-daily rainfall from daily data. The impact of climate change on rainfall IDF over Barcelona (Spain) is considered by Rodríguez et al. (2013). This change is analyzed from the output of five Global Circulation Models (GCM) under three scenarios including A1B, A2 and B2.

Ho Chi Minh City (HCMC) is located in the delta area of the Saigon and Dong Nai rivers. It is Viet Nam’s largest city and an important economic, trade, cultural and research centre, both within the country, and in South-East Asia. Like most cities situated in deltas, HCMC faces serious challenges due to climatic change. HCMC is ranked among the top 10 cities in the world most likely to be severely affected by climate change [2]. Major impacts of climate change are floods and droughts as a consequence of water scarcity in the dry season [8]. In addition, heavy rainfall and flooding can also contaminate surface water and affect environmental health in urban area. Thus, the understanding of changes in precipitation extremes will also be useful for HCMC in managing water urban and preventing urban flooding. However, IDF curves for future have been developed much for Ho Chi Minh City. The objective of this study was to assess climate change impact on rainfall IDF curves at Ho Chi Minh City. The firstly, present IDF is analysed based on observed data. Follow that, the rainfall projections for future periods based on

ensemble regional climate models approach are used to develop projected intensity-duration-frequency curves and their plausible changes in the middle of 21st century (2050s), and at the end of 21st century (2090s).2. Methodology and data

2.1. Data

2.1.1. Observation dataIn this study, daily rainfall observations

from the Tan Son Hoa station covering the period of 1986-2005 were collected for bias correction of the Regional Climate Model (RCM) output. In addition, rainfall data of several short duration extreme events were collected for this station. The dataset consists of rainfall in several durations including 15 min, 30 min, 45 min, 1 hr, 1.5 hr, 2 hr, 3 hr, 6 hr and 12 hr. Both daily and shorter-duration rainfall datasets are provided by Viet Nam Institute of Meteorology, Hydrology and Climate Change.2.1.2. Simulation data

To constructs rainfall IDF curves for baseline and future periods, daily rainfall datasets from four RCMs (including (i) PRECIS from Hadley - UK, (ii) CCAM from CSIRO, (iii) RegCM from ICTP, Italy and (iv) clWRF from the USA) are obtained. Each RCM has been used to calculate different climate projections based on the results from GCMs of IPCC. In total, there are 24 projections from the 4 models with 2 Representative Concentration Paths (RCP). Information about these models is described in Table 1. It is noted that, the bias of RCM simulations is corrected by using quantile mapping technique before used. The detailed steps for doing bias correction are provided in the work of MONRE (2016).2.2. Methodology

2.2.1. Temporal downscalingHigh-temporal-resolution (e.g., 15 min, 30

min, and 1-h) data are needed to create the IDF curves. Since the simulation data are only available at daily interval, it is necessary to temporally downscale the daily maximum rainfall intensity to hourly or sub-hourly rainfall


intensities for different return periods. For the purpose of constructing rainfall IDF curves for the future period, scaling theory was applied to produce short-duration rainfall intensity from daily rainfall data. The scaling property is proven by many studies and is applied to rainfall intensity by Menabde (1999), Le et al. (2007), and Mishra et al. (2011).

Based on empirical evidence, it is assumed and verified that random variable Id and ID as annual maximum rainfall intensities over time duration d and D respectively can have the following scaling property (Menabde et al., 1999):

In equation 1, the equality refers to the identical probability distribution for both variables and η represents the scaling exponent. The relationship between the moments of order q can be obtained by raising both sides of the equation to power q and taking the expected values of both sides (equation 2).

Estimation of scaling exponent η is illustrated in Figure 1 which includes (i) log-log graph of moments E[Iq

d] versus durations of different order q; and (ii) linear graph of slopes

(of moments versus duration lines) and moment order q. If the resulting graph is a straight line i.e., value of η (slope) remain same for different values of q, it is of simple scaling otherwise it is of multi-scaling. 2.2.2. Rainfall IDF curves construction

The rainfall IDF curve is constructed by using short-duration rainfall observations from the Tan Son Hoa station. The Gumbel distribution is chosen for conducting frequency analysis. The cumulative distribution function can be expressed as below:

where i is rainfall intensity, μd and σd are

the location and scale parameters respectively, and Fd (i) is the non-exceedance probability of intensity i in duration d.

To obtain the rainfall intensity i from a given probability or return period, we find the inverse of function (3) by taking the natural logarithm of the left side twice. After doing this step, function (4) is derived:

where T is the return period. The relationship

between the return period T and the non- exceedance probability Fd is shown in function (5):

Table 1. Information on RCMs

No. RCM Organization Driving GCMs Resolution, Domain Vertical level1 clWRF NCAR, NCEP, FSL, AFWA,... 1. NorESM1-M 30 km,

3,5÷27oN and 97,5÷116oE

27

2 PRECIS Hadley, UK 1. CNRM-CM52. GFDL-CM3

3. HadGEM2-ES

25 km, 6,5÷25oN and

99,5÷115oE

19

3 CCAM CSIRO, Australia 1. ACCESS1-0 2. CCSM4

3. CNRM-CM54. GFDL-CM3

5. MPI-ESM-LR6. NorESM1-M

10 km, 5÷30oN and

98÷115oE

27

4 RegCM NCAR, USA 1. ACCESS1-02. NorESM1-M

20 km, 6,5÷30oN and 99,5÷119,5oE

18

( )qq qd D

dE I E I

D

η− =

(2)

d Dd

I ID

η− =

(1)

( ) -exp -exp - d

dd

iF i

µσ

=

(3)

1ln ln 1d di

Tµ σ

= − ∗ − −

(4)


43

(5)

2.2.3. Ensemble percentilesIn climate change scenario, the state of

climate in the future is addressed base on greenhouse gas (GHG) Concentration scenarios. Different GHG input for climate model generates different climate change scenario. In addition, there are many uncertainty sources inside the model as well as from the outside. It is indicated that the uncertainty in climate change scenario is very clear for any region in the world. Therefore, it is indispensable to consider several situations and state of climate in the future with different RCMs and under some GHG Concentration scenarios. To synthesize the ensemble simulations, this paper is following the approach used in the UK Climate Projections report (Murphy et al., 2009). To allow for more freedom in exploring the uncertainties associated with the simulations, this paper select two typical percentiles (50th, and 75th) to summarize the possible outcomes of future projections:

The most likely case: This case is obtained by calculating the 50th percentile of all IDF

projection members. The 50th percentile is used here to represent the central value of the distribution, indicating that half of the members are less than or equal to it.

High impact case: This case is the 75th

percentile of all IDF projection members. The 75th percentile is to indicate very likely to be less than or very unlikely to be greater than.3. Results and Discussion

3.1. Observed IDF curvesAverage intensities of rainfall in duration

from 15 minutes to 1 days for several return periods from 2 years to 100 years at Tan Son Hoa station are shown in Table 2 and Figure 2 performs the graph of IDF relationship at Tan Son Hoa station.

For 100-year return period, this is a very rare occurrence, average rainfall intensity in 15 minutes is 222 mm/hour. If this intensity remains for 15 consecutive minutes, the total accumulated rainfall at Tan Son Hoa station will be around 55.5 mm. In 46 years of observation data used in this study (not shown in the paper), this event has never happened. In 1-hour duration, average rainfall intensity is 129.9 mm/hour. The intensity which is equal or greater than that

Figure 1. Simple scaling and mutil-scaling (Le Minh Nhat, 2008)

11 d

TF

=−


value has occurred for one time in 2016. Average daily intensity is 7.3 mm/hour corresponding to 175.2 mm total rainfall in a day. The one-day maximum rainfall in the period from 1971-2016 is 171 mm, which occurred on 26/09/2016.

For 50-year return period, average rainfall intensity in 15 minutes is 206.8 mm/hour. This rain event also has not happened in the period from 1971-2016. With the duration of 1 hour and 24 hours, average rainfall intensity is 120.2 mm/hour and 6.7 mm/hour, respectively. These two rain events have only occurred once, in 2016 with 1-hour duration and 1994 with 1-day duration.

For 25-year return period, the average rain intensity in 15 consecutive minutes is 191.5 mm/hour. In 46 years of observation data, there was one time that heavy rain with the intensity is greater than 191.5 mm/hour occurred, in 2000.

With the duration of 60 minutes, average rain intensity is 110.4 mm/hour, this rain event happened two times, in 1981 and 2016. With the duration of 24 hours, average rain intensity is 6.2 mm/hour, the corresponding total precipitation accumulated in 24 consecutive hours is 148.8 mm. This event also occurred in 1994 and 2016.

For 2-year return period: Correspond to rain duration in 15 minutes, average rainfall intensity is 130 mm/hour. In 46 years of observed data, the rain event with intensity higher or equal to 130 mm/hour has happened 25 times. Average rainfall intensity in 60 minutes is 70.9 mm/hour, occurred 26 times in 46 years of observed data. With the duration of 24 hours, average rainfall intensity is 4 mm/hour, corresponding to the total rainfall accumulated in 24 consecutive hours of 96 mm. This event has happened 24 times in the period from 1971-2016.

Table 2. Average rainfall intensity (mm/hour) in several durations and return periods at Tan Son Hoa station from short duration observation data (1971-2016)

15' 30' 45' 60' 90' 2h 3h 6h 12h 24h2 years 130.0 100.7 85.2 70.9 51.5 40.0 28.3 14.2 7.1 4.05 years 154.6 121.8 102.4 86.7 64.3 50.2 35.7 17.9 8.9 4.9

10 years 170.9 135.7 113.8 97.1 72.7 56.9 40.6 20.3 10.2 5.425 years 191.5 153.2 128.2 110.4 83.4 65.4 46.8 23.4 11.7 6.250 years 206.8 166.3 138.9 120.2 91.3 71.7 51.4 25.7 12.8 6.7

100 years 222.0 179.2 149.5 129.9 99.2 78.0 55.9 28.0 14.0 7.3

Figure 2. Rainfall IDF curves at Tan Son Hoa station from short duration observation data (1971 - 2016)


45

3.2. Projected IDF curves

3.2.1. The most likely case (percentile 50%)The change of rainfall intensity in

several durations and return periods for future periods relative to the baseline period is shown in Table 3 and Table 4. The changes are presented as relative percentages, and positive values indicate percentage increases relative to the baseline projections, whereas negative ones indicate percentage decreases. The result shows that the regional modeling ensemble is likely to project an overall increasing pattern in the intensities of all extreme rainfall events. The projected changes in rainfall intensities for all durations also show an apparent increasing trend with time. The change for 2050s are mostly in the range of 11% and 60%, the changes for 2090s are mainly ranging from 15% to 69%. The changes depend on various durations return periods.

In the middle of the century (2046-2065): For the 100-year return period, rainfall intensity in 15-minutes duration tends to increase by 38.8% that corresponds to the intensity of 326.8 mm/hour. In 60-minute duration, the intensity is 194.6 mm/hour and its upturn is 56.4%. The increase in 24-hour duration is 40.1%. 24-hour duration average intensity in the middle of the 21st century is 10.2 mm/hour; For 50-year

return period, average rainfall intensity in the duration of 15 minutes, 60 minutes and 24 hours will increase by 35.7%, 52.7% and 37.7% respectively. With the duration of 24 hours, the average rainfall intensity is 9.3 mm/hour; For 25-years return period, average rainfall intensity at Tan Son Hoa station in 15 minutes will be 264.4 mm/hour (by 32%). With the duration of 60 minutes and 24 hour, average rainfall intensity will increase by 48.5% and 38.2% respectively; For the 2-year return period, the increment of rainfall intensity in 15-minutes, 1-hour and 24-hours duration is respectively 11%, 21.8% and 29.9%.

In the end of the century (2080-2099): For the 100-year return period, average rainfall intensity in durations of 15 minutes and 60 minutes will increase by 54.6% and 63.9%, while in duration of 24 hours will increase by 69%; For the 50-year return period, average rainfall intensity in 15 minutes will increase by 49.5%. With 60 minutes duration, average rainfall intensity will increase by 58.7%, and with 24-hour duration, average rainfall intensity will increase by 66%; For the 25-year return period, average rainfall intensity in 15 minutes and 60 minutes will increase by 43.6% and 52.1%. In 24 hour duration, it will also increase by 64.1%; For the 2-year return period, the average rainfall intensity in 15-minutes, 1-hour and 24-hours duration is respectively 15.4%, 30.5% and 47.2%.

Table 3. Change in rainfall intensity (%) in several durations and return periods at Tan Son Hoa station in the middle of 21st century in the most likely case



100 years 38.8 38.1 48.1 56.4 58.0 57.7 55.8 60.6 45.5 40.1


Table 4. Change in rainfall intensity (%) in several durations and return periods at Tan Son Hoa station at the end of 21st century in the most likely case



100 years 54.6 50.1 57.7 63.9 62.0 59.6 53.8 56.8 57.8 69.0

3.2.2. The higher impact case (percentile 75%)The change of rainfall intensity in

several durations and return periods for future periods relative to the baseline period in case of higher impact is shown in Table 5 and Table 6. The result shows that rainfall intensity may increase substantially in all durations and return periods by both two future periods. Similar to the most likely case, the projected changes in rainfall intensities for all durations also show an apparent increasing trend with time. The change for 2050s are mostly in the range of 38% and 141%, the changes for 2090s are mainly ranging from 28% to 105%. The changes depend on various durations return periods.

In the middle of the century (2046-2065): With 100-year return period, average rainfall intensity in the duration of 15 minutes will increase by 141.6% with the value of rainfall intensity of 568.8 mm/hour. Average rainfall intensity in 60 minutes and 24 hours durationswill be 282.5 mm/hour (by 127%) and 13.5 mm/hour (by 85.9%) ; With 50-year return period, average rainfall intensity of 15 minutes and 60 minutes durations will increase by 137.3%, 121.8% respectively. With the duration of 24 hours, average rainfall intensity will increase by 79%; With 25-year return period, projected rainfall intensity in the duration of 15-minutes increase by 131.3%. In 60-minutes duration, rainfall intensity is expected to increase 115.5%. 74.2% is the expected increase in rainfall intensity in 24-hours duration; With 2-year return period, rainfall intensity is expected to increase by 90.2%, 73.3% and 38.5% in 15-minutes,

60-minutes and 24-hours duration, respectively.In the end of the century (2080-2099):

For 100-year return period, average rainfall intensity in 15 minutes duration with the value of 397.6 mm/hour will be an upward trend by 68.9%. In 60 minutes and 24 hours durations, it will increase by 87.7% and 84.9%; For the 50-year return period, average rainfall intensity in 15 consecutive minutes will be 361.4 mm/hour, increasing by 65.9%. With 60 minutes and 24 hours durations, it will increase by83.4% and 82.3% respectively; For 25-year return period, average rainfall intensity in 15 minutes, 60 minutes and 24 hours durations will increase by 62.6%, 79.0% and 81.9%, respectively; For the 2-year return period, average rainfall intensity in 15 minutes will increase by 31.7%, reaching 170.2 mm/hour. With 60 minutes and 24-hours duration, the increase in rainfall intensity will be 34.4% and 68.2%, respectively. 4. Conclusions

In this study, the rainfall projections for future periods based on ensemble regional models approach are used to develop projected intensity-duration-frequency curves and their plausible changes in the middle of the 21st

century (2050s), and at the end of 21st century (2090s) for the Ho Chi Minh City, Viet Nam. To cope with the uncertainty of climate change projection, the ensemble of the final result was divided into two following cases: i) the most likely case (percentile 50%) and high impact case (percentile 75%).

Based on the results of this study, it can be concluded that the intensities of extreme


47

References1. Akpan, S.U. and Okoro, B.C. (2013), “Developing Rainfall Intensity-Duration-Frequency Models for

Calabar City, South-South, Nigeria”, American Journal of Engineering Research (AJER), 2(6), 19-24.2. Asian Development Bank (2010), Ho Chi Minh City Adaptation to Climate Change - Summary

report.3. De Paola, F., Giugni, M., Topa, M.E. and Bucchignani, E. (2014), “Intensity-Duration-Frequency (IDF)

rainfall curves, for data series and climate projection in African cities”, SpringerPlus, 3(133).4. IPCC (2013), Climate Change 2013: The Physical Science Basis, Contribution of Working Group I to

the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.5. Le,M.N., Tachikawa, Y. and Takara, K. (2006), Establishment of Intensity-Duration-Frequency Curves

for Precipitation in the Monsoon Area of Viet Nam. Annuals of Disas. Prev. Res. Inst., Kyoto Univ.,

rainfall events versus various durations with different return periods are all likely to increase over time in comparison with baseline period (1986-2005): [11, 60]% in 2050s, and [15, 69]% in 2090s under most likely case; and [38, 141]% in 2050s, and [28, 105]% in 2090s under high impact case. Such a consistent increase in the exceedance values of rainfall intensity of extreme events, implying that intense rainfall events are likely to occur more frequently in the future under climate change. Results of this

Table 5. Change in rainfall intensity (%) in several durations and return periods at Tan Son Hoa station in the middle of 21st century in high impact case



100 years 141.6 119.8 123.0 127.0 117.7 109.4 96.8 72.8 81.6 85.9

Table 6. Change in rainfall intensity (%) in several durations and return periods at Tan Son Hoa station at the end of 21st century in high impact case



100 years 68.9 65.9 77.9 87.7 89.8 89.2 86.3 105.7 88.4 84.9

study are of significant practical importance for design, operation and maintenance of storm water management infrastructures under the changing climate in Ho Chi Minh City.

Acknowledgments: This research was supported by the Department of Science and Technology of Ho Chi Minh City, under the Project no. 108/2017/HĐ-SKHCN. The authors wish to acknowledge the financial assistance received.


No. 49 B, 2006.6. Le,M.N. (2008), Development of Intensity-Duration-Frequency Relationships Based on Scaling

Characteristics of Rainfall Extremes, Doctoral Dissertation.7. Logah, F., Yeboah, K.K. and Bekoe, E. (2013), “Developing Short Duration Rainfall Intensity

Frequency Curves for Accra in Ghana”, International Journal of Latest Research In Engineering and Computing (IJLREC).

8. Noi,L.V.T. and Nitivattananon, V. (2015), Assessment of vulnerabilities to climate change for urban water and wastewater infrastructure management - case study in Dong Nai river basin, Viet Nam, Environmental Development, DOI: 10.1016/j.envdev.2015.06.014

9. Menabde, M., Seed, A. and Pegram, G. (1999), “A simple scaling model for extreme rainfall”, Water Resources, 35(1), 335-339.

10. Ministry of Natural Resources and Environment (2016), Climate Change, sea level rise scenarios for Viet Nam, Viet Nam Publish House of Natural Resources, Environment and Cartography, Ha Noi.

11. Mishra, B.K. and Herath, S. (2011), “Rainfall intensity duration frequency curves under climate change scenario in urban Kathmandu valley”, NEA-JC Newsletter, 6(2), 19-22.

12. Murphy, J.M.et al. (2009), UK climate projections: Climate change projections, Met Office Hadley Centre Rep. UKCP09, 190 pp.

13. Le, M.N., Tachikawa, Y., Sayama, T. and Takara, K. (2007), Regional rainfall intensity duration- frequency relationships for ungauged catchments based on scaling properties, Annuals of Disas. Prev. Res. Inst., Kyoto Univ., 50B, 33-43.

14. Rodríguez, R., Navarro, X., Casas, M.C., Ribalaygua, J., Russo, B., Pouget, L. and Redaño, A. (2014), “Influence of climate change on IDF curves for the metropolitan area of Barcelona (Spain)”, Int. J. Climatol., (34), 643-654.

15. Nguyen, V.T.V, Nguyen, T.D. and Cung, A. (2007), “A statistical approach to downscaling of sub-daily extreme rainfall processes for climate-related impact studies in urban areas”, Water Science & Technology: Water Supply, 7(2), 183-192.


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THE USE OF COMBINED TOP-DOWN AND BOTTOM-UP CLIMATE CHANGE IMPACT ASSESSMENT IN HYDROLOGICAL SYSTEMS

Tran Van Tra(1), Nguyen Xuan Thinh(2)

(1)Viet Nam Institute of Meteorology, Hydrology and Climate Change; Doctoral Student, TU Dortmund University

(2)University Professor, Faculty of Spatial Planning, TU Dortmund University


Abstract: Climate change impact assessment in hydrological systems in the past is of a top-down nature. In particular, future climate states are predicted using scenarios and climate models. Although the approach could provide optimal adaptation measures for the intended future, its applications may be increasingly limited as there are large uncertainties. The top-down approach provide too much of the wrong information for policy makers. Bottom-up approaches in climate change impact assessment have also been used in the past as an alternative. The strength of the approach lies in its ability to provide robust adaptation options since the focus is on the vulnerability space, not the prediction of future climate space. Nonetheless, without the information from a top-down approach, the bottom-up approach would lack a basis for selecting the range of climate states to test the vulnerability of the system. The vulnerability exploration would be imprecise and unbounded, and of limited decision-making value. For this reason, a more recent development of a combined top-down and bottom-up approach has been advocated. The combined top-down and bottom-up approach uses top-down information such as climate model outputs while still focuses on the vulnerability space of the system. Through the approach, relevant climate conditions that poses threat to the system could be identified. This paper provides a summary of the top-down and bottom-up approach and introduces more recent development in the combined top-down and bottom-up climate change impact assessment approach.

Keywords: climate change, impact assessment, top-down, bottom-up, combined.

1. IntroductionThe interaction between science and

policy have been formalized into three categories namely: “science push”, “demand pull”, and “science push and demand pull” (Dilling and Lemos, 2011; Stokes, 1997). A “science push” mode is characterized by the pursuit of knowledge serving as the driver for scientific discoveries (Stokes, 1997). A “demand pull” mode on the other hand, is where the demand for a solution to a specific problem from stakeholders drives science into production. A combination of the two modes result in a “science push and demand pull”, where the research agenda is determined

through a process of knowledge exchange between producers and users (Lemos and Morehouse, 2005).

One important component in the modes of science production is who drives the agenda for what is produced. Science products obtained from a “science push” mode may be useful for real life applications, but in many cases can be of limited practical use. This can be represented by a “loading dock” approach where information is simply loaded and may not be picked up by the users (Cash et al., 2006). A “demand pull” mode of science production is more practical since it attempts to solve a real problem. However, in many cases, the demand for information and science to be produced may be highly infeasible for scientists (Weiss, 1978). Therefore, in an ideal state, a co-production scheme and exchange of information between user and producer, i.e.

Correspondence to: Tran Van TraE-mail: [email protected]


“science push and demand pull” mode is desired. Within the context of climate change impact

assessment in hydrological systems, traditionally, a top-down scheme is applied. Scenarios of future climate state is predicted through climate models such as General Circulation Models (GCMs). Hydrological models are then used to predict the response of the hydrological systems based on the predicted future climate to determine the impacts. Finally, adaptation responses are proposed. The approach has been formalized into a seven step procedure by the United Nations Framework Convention on Climate Change (UNFCCC).

However, it has been contested that there exist an imbalance of focus between climate science production and climate change adaptation responses. More scientific effort is being expended on characterizing the uncertainty in climate change projections than on developing adaptation responses to a range of plausible climate outcomes (Wilby and Dessai, 2010). Scientists have been producing too much of the “wrong type of information” for policy makers. (Prudhomme et al., 2010; Brown et al., 2012; McNie, 2007; Dilling and Lemos, 2011). Information provided from a top-down approach is limited and highly impractical for adaptation responses development. The type of climate science information provided by a top-down approach have been characterized by a “science push” mode. Little attention has been paid to the “demand pull” side.

Given the limitation of the previous approach in supporting decision making, more appropriate approaches are required. A bottom-up approach in climate change impact assessment in hydrological systems have been used as an alternative. The approach focuses on the vulnerability of the system and shifts away from predicting future climate conditions. The bottom-up approach, however, is not without its limitations. More recently, a combined top-down and bottom-up approach has been advocated. Such an approach attempts to combine the strength of the top-down and the bottom-up approach while eliminating their limitations. This paper discusses the three

approaches in climate change impact assessment in hydrological systems mentioned above. The purpose is to provide a general overview of the different methods and their applicability for future potential users such as policy makers and other relevant stakeholders. 2. The top-down approach

2.1. Overview of top-down approachesEarly impact and adaptation studies of

climate change adopted a scenario-based approach under given GCM scenario. Within each scenarios, risks and vulnerability in future climate states are identified and adaptation responses proposed. Although the impact assessments can vary to some degree, earlier impact and adaptation studies of climate change follows a formal step-by-step approach. The approach was presented as a seven-step analytical framework by the first UNFCCC Conference of the Parties in 1995 (Carter and Mäkinen, 2011).

This type of approach is more commonly referred to as a top-down approach to climate impact assessment because it relies on top-down information of global climate projections (Carter and Mäkinen, 2011). The true analysis starts with climate change projections from a single or a range of GCMs. The projections from GCMs are normally coarse in resolution (several hundred kilometres). To make use of these projections, downscaling techniques needs to be applied so that the results could be represented at the similar temporal and spatial scale with the hydrologic projections of climate change to drive water resources systems models (Brown et al., 2012). The depiction of a top-down approach is shown in Figure 1. 2.2. Downscaling in top-down approach

One key component in the top-down climate adaptation studies, as mentioned above, is the GCMs. To date, GCMs are still considered to be the only credible tools available for simulating global climate system response to increasing GHG concentrations (Tofiq and Guven, 2014). However, the coarse spatial scale of GCM meant that to be able to utilize the projections at local


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Figure 1. Top-down climate change impact assessment

scale, downscaling is required. Scientific literature of the past decade

consists a large number of studies regarding the development of downscaling methods and the use of hydrological models to assess the potential effects of climate change on a variety of water resource issues. Hydrological models provide a framework to conceptualize and investigate the relationship between climate and water resources (Xu, 1999). The most relevant meteorological variables for hydrological impacts studies are temperature and precipitation (Maraun et al., 2010).

The statistical downscaling approach seeks to establish a statistical relationship between large scale variables such as atmospheric pressures and a local variable such as wind speed at a particular site of interest. A number of studies were conducted by using statistical downscaling and different GCM scenarios to predict the runoff based on precipitation and rainfall-runoff models (Yonggang et al., 2013; Chen et al., 2012; Nam et al., 2011).

Dynamic downscaling relies on driving Regional Climate Models (RCM) using outputs obtained from GCMs. RCM have higher spatial resolution and can represent climate variables at the local scale of interest (Tofiq and Guven, 2014). Examples of researches in the past that used the dynamical downscaling approach includes Vo et al. (2016), Maraun et al. (2010), and Xue et al. (2014).2.3. The limitation of a top-down approach

One of the major criticism of the traditional

approach has been the uncertainties that entails climate prediction, i.e. GCMs and downscaling. Three main sources of uncertainties include scenario development uncertainty, scientific uncertainty, and natural variability. Within each phase of the top-down approach, uncertainties cascade, creating an even larger envelop of uncertainty once adaptation response are proposed (Figure 2).

The first source of uncertainty lies in the future economic development and emissions scenario. Emissions of greenhouse gasses in the future is highly dependent on socio-economic development and demographic change in the future, technology advances, and policies (García, L.E. et al., 2014). Given the limited in-formation at present time, it is not possible to provide an accurate depiction of the future state to these variables.

Scientific uncertainty is another factor within the cascade of uncertainty. This is a result of the imperfect knowledge of the functioning of the climate system and of the affected systems. For instance, one can clearly state that there are uncertainties related to the response of the global mean temperature to a given quantity of GHGs together with the uncertainty in the regional effects of climate change (Stéphane Hallegatte et al., 2012).

Natural variability contributes further to the lists of uncertainties in the top-down approach. The uncertainty arise due to the natural dynamics of the climate system, linked to the chaotic nature of the system that has been observed


in the past. In that, climate models can estimate statistical nature (averages, variance, likelihood to exceed threshold) but not forecasts, i.e. deterministic prediction of the future (Stéphane Hallegatte et al., 2012).

The top-down climate impact assessment approach provides a useful tool to assist the process of adaptation. However, it fails to deliver the required information that may be useful to decision makers. This is mostly due to the heavy reliance on GCM models. Firstly, by relying heavily on GCMs, the approach only assesses a number of scenarios based on global emissions scenarios including the more up-to-date RCPs (representative concentration pathways) as described by IPCC (2013). This is because downscaling of GCMs is demanding. Secondly, there are large uncertainties in GCMs as described above (García, L.E. et al., 2014). In utilizing GCMs, there is a risk of having a cascade of uncertainty starting with hard-to-predict human behavior to derive emissions scenario, uncertainties in model parameters and structures, natural climate variability, and the underlying science that is being used to develop GCMs. The uncertainty is represented by a range of projected scenarios by different GCMs. Variability in projections from different models can be so large that to plan for one projection will strictly be contradictory to the other. In cases where there is a consensus between a broad range of models and scenarios, the implication is that there exists a consensus between the assumptions in the different range of models (García, L.E. et al., 2014).

Figure 2. Uncertainties related to a top-down approach (Wilby and Dessai, 2010)

Traditional decision making processes work through the prediction of a future state, and the design of plans or projects for the conditions of that state. This approach produces optimal results for the intended future; however, its application may be increasingly limited as there are large uncertainties.3. Bottom-up Climate Change Assessment

3.1. Overview of bottom-up approachesAnother approach to the study of climate

change follows a different path by shifting the focus away from impact assessment to adaptation. This is due to the understandingthat the inertia of climate change will necessitate adaptation measures in the long term (Bhave et al., 2014). An important implication of such a shift includes relying less on GCM models. The shift resulted in the use of a bottom-up approach.

In contrast to top-down approaches, bottom-up climate assessments start with the vulnerability domain (instead of GCMs). A bottom-up approach analyze the important system characteristics, local capacities before testing the sensitivity and robustness of adaptation options against climate projections (García, L.E. et al., 2014). The difference between a top-down and a bottom-up approach could be best understood using the equation describing risk by Plate (2002):

where R(x) describes risks, f(x) is the

( ) ( ) ( )0

R x C x f x dx∞

= ∫


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probability density function of the event (e.g. the occurrence of a future climate state) and C(x) is the consequences of the event. The consequence can be either listed as positive or negative. A negative consequence would be a case where damage to lives and property is done, on the other hand, a positive consequence is where benefit from the event is yielded. The top-down approach to climate change impacts assessments emphasizes estimating f(x), that is, the future distribution of climate or hydrological variables. With a bottom-up approach, the focus is on C(x), i.e. the response of the system to all the possible values of x, , without regard to f(x) (Brown et al., 2011).

The key strength of the bottom-up approach is describing the characteristics and local vulnerabilities of the system. Bottom-up approaches are more relevant than top-down approaches since climate change impacts on hydrological systems are difficult to untangle

or correlate with hydrological changes (García, L.E. et al., 2014). Results obtained from such an approach is, hence, more usable to the decision making community. This aspect of the approach provides more relevant tools to bridge the gap between researchers and decision makers in the water sector in particular.

The bottom-up approach allows low-regret adaptation measures as well as promotes robust adaptation for a wide range of uncertainty in future climate projections. In general, a bottom-up approach provides the tools for a “demand pull” mode of scientific production. In that, stakeholders and policy makers could provide researchers the information required for a risk assessment; researchers in turn, uses the expertise to determine the level of vulnerability and risk for a particular area/ project and provide feedback information that are useful to decision makers. A visual depiction of a bottom-up approach is shown in Figure 3.

Figure 3. Bottom-up climate change impact assessment

3.2. Robust decision making in bottom-up approach

Bottom-up approaches accepts uncertainty via robust decision processes. A robust decision process implies the selection of a project or plan which meets its intended goals, e.g. increase access to safe water, reduce floods, and upgrade slums, or many others- across a variety of plausible futures. The approach starts by looking into the vulnerabilities of a plan (or set of plans) to a field of possible variables. A set of plausible

futures are then identified, incorporating sets of the variables examined, and evaluate the performance of each plan under each future. Finally, plans that are robust to the highly likely or important future scenarios could be identified (Stéphane Hallegatte et al., 2012).

As robust processes imply the acceptance of uncertainty, they also demand a process of dialogues to determine which project vulnerabilities to consider, which performance metrics suggest success, acceptable levels of risk, and which possible scenarios to evaluate. The stakeholder information exchange process


is an opportunity to further fortify the project against uncertainty, as a variety of viewpoints and concerns can simultaneously be addressed in distinct scenarios. Incorporation of multiple scenarios builds consensus on the outputs (the project) despite differing inputs.

Methods that have been proposed to cope with deep uncertainty in investment decisions are rich in the literature. Most notably among those are the cost benefit analysis, and real option analysis (Dotsis and Makropoulou, 2005; Stéphane Hallegatte et al., 2012).

The cost-benefit approach (CBA) involves six individual steps namely: 1) identify competing projects; 2) identify sources of uncertainty and future possible states of the world; 3) evaluate the costs and benefits for each project; 4) calculate the present value of costs and benefits; 5) calculate the net present value of different competing projects; and 6) evaluate the robustness of the results (Stéphane Hallegatte et al., 2012). The CBA is highly useful and should encompass the whole set of possible assumptions to check its robustness. In situations with limited uncertainty, CBA can be helpful to identify the best investment options. In a situation of deep uncertainty, CBA could be used as a complement tool to open consultations and discussions (Stéphane Hallegatte et al., 2012).

In a context of increasing knowledge and thus decreasing uncertainty, the decision on an investment project is no longer between investing or not investing but between investing now and investing later with more information. To help making this type of decision, some have proposed to mobilize the real option approach, which was initially developed for financial markets (Dotsis and Makropoulou, 2005; Stéphane Hallegatte et al., 2012). The analysis of real options does not differ from a classical cost-benefit analysis, except that the Net Present Value includes additional consideration, namely the options created and destroyed by the project. 4. Combination of top-down and bottom-up approaches

A bottom-up approach allows robust, and low-regret decision making in the context of

climate change adaptation in hydrological systems. However, it still requires top-down information to inform the likelihood of future climate conditions. The scientific understanding of physical climate mechanisms (and specifically, response to changes in radiative forcing) informs the experiments performed used bottom-up techniques. Without these inputs from the physical climate modeling community, the bottom-up approach would lack a basis for selecting the range to test the vulnerability of the system. The vulnerability exploration would be imprecise and unbounded, and of limited decision-making value (García, L.E. et al., 2014).

For this reason, a number of researchers have attempted to use a slightly modified bottom-up approach where scientific information from a top-down approach is also included. The result is a combined top-down and bottom- up approach. While a top-down approach represent a “science push” mode of scientific production, a combined top-down and bottom-up approach attempts to represent a “science push and demand pull” mode of scientific production. The main rationale of the combination is the hope that more reliable and useful information could be produced for climate change adaptation in hydrological systems.

Prudhomme et al. (2010) proposed a scenario-neutral approach in assessing flood risks in two river catchments located in the UK. The study differs from the top-down approach in the way climate change risks (the hazard) is separated from the catchment responsiveness (the vulnerability). The approach proceeds in three steps. Firstly, a reference climatology period for the region of interest was determined. Secondly, the absolute or percentage changes in the equivalent variable are calculated for the GCM grid-box closest to the target site using projections for a specified period in the future. Thirdly, the change suggested by the GCM is simply added to the reference climatology and the resulting time series are used for impacts modeling. Four main information sources are used in the framework: (1) the climate change allowance or


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safety margin, (2) a mathematical model of the climate response system, (3) an ensemble of climate change projections, and (4) metrics to show the likelihood that the safety margin is

robust to the available sample of climate change projections. The conceptual framework is shown in Figure 4.

Figure 4. Scenario-neutral conceptual framework (Prudhomme et al., 2010)Wilby and Dessai (2010) described a

process that sifts for robust adaptation, measures that are low regret or reversible. This includes constructing an inventory of adaptation options containing both hard engineering as well as soft solutions. Through screening, adaptation measures that reduce vulnerability in current climate regime could be identified. For shorter life-time projects for a few years

or less, the measures could be tested using current climate schemes. However, if the life-time of a project exceeds multiple decades (such as irrigation systems and reservoirs), performance of the adaptation projects would need to be evaluated across a range of scenarios. The use of Regional Climate Downscaling is then utilized for such cases. The full conceptual framework is shown in Figure 5.

Figure 5. Conceptual framework in Wilby and Dessai (2010)


Bhave et al. (2014) combined the two aspects of bottom-up and top-down climate change adaptation via the use of hydrological models to assess the effect of stakeholder prioritized adaptation options for the Kangsabati River catchment in India. A series of 14 multi-level stakeholder consultations are used to ascertain locally relevant no-regret adaptation options using Multi-Criteria Analysis (MCA) and scenario analysis methods. A validated Water Evaluation and Planning (WEAP) model is then used to project the effect of three options: check

dams (CD), increasing forest cover (IFC), and combined CD and IFC, on future (2021-2050) streamflow. High resolution (roughly 25 km) climatic projections from four Regional Climate Models (RCMs) and their ensemble based on the SRES A1B scenario for the mid-21st century period are used to force the WEAP model. The authors then concluded that such an integrated approach is advantageous and could provide relevant adaptation information for local policy makers. The schematic of the approach is depicted in Figure 6.

Shaw et al. (2009) and Sheppard et al. (2011) adopted a combination of top-down and bottom-up approach through a future visioning process (Figure 7). The studies identified that uncertainties of a top-down approach with heavy reliance on GCM complicate the process of policy making in climate change adaptation. The studies propose a future visioning process, a conceptual framework that generates alternative, coherent, holistic climate change scenarios and visualization at the local scale, in collaboration with local stakeholders and scientists. In essence, a range of future climate scenarios that is deemed relevant through scenario development workshops with stakeholders was chosen so that local impacts could be determined. Local visualization are then determined showing the effects of the climate change scenarios with and without

Figure 6. Schematic representing the approach used by Bhave et al.(2014)

adaptation measures.Another recent framework that has gained

attention is the decision scaling process (Brown et al., 2012; Brown, 2011; Brown et al., 2011). The approach links bottom-up, stochastic vulnerability analysis with top-down use of GCMs. In that, it uses stochastic analysis for risk identification and uses GCM projections for risk estimation, assigning probabilities to hazards, thus linking the two methods. Three different steps would be required. Firstly, the vulnerabilities of the system to changes are evaluated in a large climate space. Secondly, the climate domain is mapped onto the vulnerability domain. Thirdly, the risks to project performance are determined. Adaptation measures are then evaluated to reduce the risks associated with the project (Figure 8).


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Combined top-down and bottom-up climate change impact assessment in hydrological systems has been extensively advocated and used by the research community. The approach does not provide one silver bullet to solve the issue of uncertainties related to climate change impact assessment in hydrological systems, but provided an alternative to the less capable

Figure 7. Future Visioning Process (Sheppard et al., 2011)

traditional top-down and bottom-up approach. Given the approach is recent as compared to the top-down approach, there has been no formalized procedural steps established that could work with all problems in general. Different researches have created their own conceptual framework that may or may not be relevant for a particular research as can be seen.

Figure 8. Decision-scaling conceptual framework (Brown et al., 2012)


The implication for future combined top-down and bottom-up climate change impact assessment in hydrological systems is manifolds. Future climate change impact assessment could potentially adopt an entire conceptual framework, or be selective on the components to be included, and even combine the several components within each combined top-down and bottom-up conceptual schemes. For example, one could very well combine a decision scaling process with the future visioning process as described above. A decision scaling framework would allow the assessment of relevant climate conditions while the future visioning process allows the communication of these conditions to both local population and policy makers. This provides an even greater research demand in formalizing the combined top-down and bottom-up approach. 5. Conclusions

Climate change impact assessment in hydrological systems have historically relied on a top-down approach. Although the approach could potentially provide useful information for decision makers for adaptation measures, this has not been the case. This is due to the large uncertainties that entails the top-down approach including scenario development uncertainty, scientific uncertainty, and natural variability uncertainty.

To overcome such uncertainties, a bottom-up approach has been used. For most climate change impact assessment applications in water resources management, bottom-up approaches are more relevant than top-down approaches since climate impacts are difficult to untangle or correlate with hydrological changes. However, bottom-up approaches still require input from top-down approach to provide the basis for selecting the range over which to test the vulnerability of the system. The

vulnerability exploration from a bottom-up approach would be imprecise and unbounded, and of limited decision-making value without top-down information.

For this reason, a combination of top-down and bottom-up climate change impact assessment method has been advocated. The aim of such a new approach is to combine the strength of the previous two approach while reducing their limitations. Through such an approach, climate change scenario screening could be performed to filter climate conditions that are potentially problematic and requires adaptation measures. Information provided from the approach could then be used by decision makers so that robust adaptation policies could be proposed.

Given that there is no formalized procedures for a combined top-down and bottom-up approach, researchers have normally created their own version of the process. This have created a large number of different conceptual frameworks. The selection of the appropriate framework is up to the researcher based on the research demand and objectives. However, one could also be selective on the choice of the framework and their components, and even combine different components within each framework.

Acknowledgement: This research is funded by the Sustainable Water Resources Management Grant Program by the German Academic Exchange Services (DAAD). The authors wish toacknowledge the financial assistance received. The authors wish to further acknowledge the valuable input and support from scientists of the Viet Nam Institute of Meteorology, Hydrology and Climate Change, Viet Nam Ministry of Natural Resources and Environment.

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FLASH FLOOD EVENTS IN MU CANG CHAI AND MUONG LA ON AUGUST 3, 2017 - CAUSES AND PREVENTION MEASURES

Hoang Minh Tuyen, Luong Huu Dung, Le Tuan NghiaViet Nam Institute of Meteorology, Hydrology and Climate Change


Abstract: In the early morning of August 3, 2017, the two flash flood events occurred in Kim Noi and Nam Pam watersheds in Mu Cang Chai and Muong La districts, respectively. The analysis of rainfall data and field surveys shows that the severe events related to extreme local rainfall (>100 mm in 6 hours) accompanying with steep topography (>40% slope) and low vegetation cover. Therefore, flood is formed fast with short concentration time. Furthermore, narrowing cross-sections on stream by 25-80% cause flow clog and temporarily generate small dams. When the amount of floodwater exceeded the capacity of these small dams, water from dam break generates flash flood and sweep everything in downstream. The paper aims to provide short- and long-term measures to prevent and reduce flash flood damages.

Keywords: flash flood, flow clogging, flash flood causes.

1. IntroductionIn the morning of 3/8/2017, flash floods

occurred in two basins of Kim Noi stream, Mu Cang Chai district and Nam Pam River, Muong La district. The flash floods caused great damages to people and property. In Kim Noi commune, 2 people died, 12 people were missing, 29 houses were completely washed away, the estimated damage is approximately 160 billion VND. In Muong La, flash floods killed 12 people, 5 people were missing, 375 houses were damaged. Especially, Na Ten village in Nam Pam commune has been wiped away, 45 households have been washed away completely. Floods destroyed many roads, electricity systems, irrigation systems and crops. The estimated damage at Muong La district has been estimated at over 660 billion VND.

a) Kim Noi watershedKim Noi is a small stream that flows into

Nam Kim stream on the left bank. The stream used to be gentle with a basin area of 5 km2, the average slope basin is 48%. The mainstream length is about 2.5 km with an average slope of 16%, dividing into two parts by stream slope. The downstream part is around 600 m from the

outlet to upstream with mild slope <10% and gradually expanding streambed. In this part, the footprint of the ancient stream is exposed to the loose rocks that are the remnants of flash floods in the past (Figure 1). Local people now still live in this area. The upstream part is steeper with a slope of over 17% and narrow streams flowing between two rocky cliffs. Stream cross-sections in this part are around 8 m corresponding to the highest flood mark. In the basin, the primeval forest is almost disappearing, and crop fields are mainly maize and rice.

b) Nam Pam watershedNam Pam is a large stream, flowing

directly into Da River immediately after Son La hydro power plant. Nam Pam basin area is about 110 km2, the average slope of the basin is about 40%. The mainstream is nearly 13 km long, stream slopes about 10.5%. The Pi Toong stream is the largest tributary to the right of the Nam Pam stream with a basin area of 34.6 km2 (accounting for one-third of the whole basin area). However, this basin has fairly flat terrain, the average slope of the basin is 30% and stream slope is only about 4%. Therefore, the potential for flash floods in the Pi Toong tributary is not high. In fact, the flash floods on 3/8/2017 and 14/8/2017 indicated that flash floods only occur along the Nam Pam stream (Figure 2).

Correspondence to: Hoang Minh TuyenE-mail: [email protected]


Figure 1. Kim Noi watershed

Figure 2. Nam Pam watershed


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2. Study on flash flood causes a) Flash flood in Mu Cang ChaiAccording to the information of the people

living upstream (Kim Noi village), heavy rain occurred from midnight to the morning of 3/8/2017. However, the rainfall from 1-7h on 3/8/2017 measured at Mu Cang Chai

station downstream is only 36 mm, not reflecting the actual situation in the basin. Rainfall measured at some upstream stations from 1h-7h on 3/8/2017 at Khau Pha is 116 mm, at Nga Ba Kim is 100 mm (Figure 3). From the landslide trail of the steep mountain slopes showed that in the upstream, extremely heavy rain could range from 100-200 mm in 6 hours.

Figure 3. Rainfall at Mu Cang Chai and Khau Pha Gauges

In addition, the total rainfall in July at Mu Cang Chai station was quite large, up to 513.5 mm which made the soil moisture saturated and soil became loose.

From the location where the Kim Noi stream flows into Nam Kim stream to the upstream about 600 m, the cross-section of the stream narrowed about 50%, the two sides of the stream are vertical cliffs, the width is only about 7-8 m. There is a deep pit at this location. From here, the release cap began to develop, streams gradually expanded. This is a congestion of the flow, trees, and rocks that make up temporary dams, forming natural water tanks for rainwater storage. When the water was big enough to break the dam, it poured down from the top abruptly,

carrying many of the rocks and soil of the ancient streams which were loose due to rain for many days, to the downstream, wiping out the houses and plants along the flow. The damaged stream is only about 500-600 m (Figure 4).

Generally, in small watersheds (<5 km2), such rainfall amount rarely generates huge amounts of water down to downstream in a short time and causing flash floods. The actual reasons are the local heavy rain and narrow streams that build up temporal reservoirs in the upstream. The reservoirs with weak dams become “water balls” and easily explode. If an upstream dam breaks, the downstream ones will consecutively break and throw huge water amount to downstream like dominos.


b) Flash flood in Muong LaComparing to Kim Noi stream, Nam La

watershed is approximate 24 times larger and the stream is 20 times longer. The flash flood in Nam La, thus, is more extreme. The observed data of 12-hour rainfall (19:00 to 7:00 3/8/2017) at Muong La station is 115 mm (Figure 5), at Khau Pha is 116 mm and at Nga Ba Kim stations near Kim Noi watershed is 100 mm. This high-intensity rainfall occurred in large basin area combining with a steep watershed accumulated to a huge amount of water that is potential for flash floods. Along the Nam Pam stream to It Ong direction, there are three sites with stream cross sections shrinks from 25-80% (Figure 2). The detailed description is given as follows.

The flash flood occurred on the Nam Pam stream, Muong La district, which stretched over 10 km along the stream from the center of Nam

Pam commune to the It Ong commune. - The 1st place: The stream flows through

Hoc village, where the river valley is narrow, the right bank is argillaceous rock steep, the left bank is less sloping, the valley is unbalancing V-shaped. The estimated area of cross-section corresponding to the height of flood mark reduced 25%.

- The 2nd place is located upstream of Na Loc village about 300 m. At this location, the valley shrinks abruptly, both 2 banks of the river are steep cliffs, the valley in the V shape, the stream bed width is about 5-10 m, the discharge section area shrank 80%.

- The 3rd place is Nam Pam Bridge. Road to the bridge, piers and abutments of the bridge narrowed the natural river cross-section by 55-60%. The flood flow of Nam Pam before passing over Nam Pam Bridge was supplemented with a large amount of water from the Nam Toong

Figure 4. Photos of Kim Noi stream after flash flood


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stream on the right. The accumulated flood of 2 tributaries met the narrow area Nam Pam

bridge and broke down the abutment bridge to the downstream (Figure 6).

Figure 5. Rainfall data at Mu Cang Chai and Khau Pha Gauges

Figure 6. Nam Pam bridge dedtroyed by flash flood


In conclusion, the causes of the flash flood in Nam Pam stream can be summarized as follows:

- The local heavy rainfall combining with steep terrain, poor vegetation cover result in rapid flood formation and short concentration time.

- Flood waters from the slopes of the basin, with a slope of more than 40%, flow into the mainstream, pulled loose soil and rock, landslide, the trees washed away followed flow caused stream obstruction at natural and artificial narrow site, forming temporary nature lakes. When the amount of water that exceeded the tolerance of temporarily natural

dams caused a dam break effect from upstream to downstream dams, creating flash flood over 10km of streams. Flood flew to It Ong to meet Nam Pam bridge, with huge amounts of water poured into congestion, causing overflow, flooding and breaking bridges to drain water to Da River.

In summary, two flash floods that occurred in the early morning of 3/8/2017 in Mu Cang Chai and Muong La are caused by locally heavy rainfall combined with water-clogging phenomenon. They are the typical floods that often occur in mountainous area with disintegration terrain and high probability of landslide.

3. Recommendation of damage reduction and flash flood prevention

Especially, in 2 basins Kim Noi and Nam Pam:- Move houses, schools etc. located in the

flood risk area;- Expand flood drainage at downstream of

Kim Noi river, especially the stadium and ethnic intern school has built and blocked the floodway;

- Expand cross-section at clogging points, especially in Nam Pam river at Na Loc village and Nam Pam bridge built across the stream in It Ong town, Muong La district;

- Adjust the flow of Nam Pam stream in accordance with the natural rules and conditions, creating clearance for the flow. Technical infrastructure planning should only be implemented after having suitable flow control planning;

- Consider the resettlement plan, optimize flatlands at a higher level than the historical flood level;

Figure 7. The picture of Kim Noi and Nam Pan stream after flash flood

- In the long-term period, reforestation should be encouraged among local people.

To minimize flash flood damage long-term solutions that needs to be implemented are:

- Investigate the upstream and downstream where has a high density of population and infrastructures. Assess flood risk for these sub-basins.

- Identify high flash flood risk streams which potentially affect the population, infrastructures. Conduct topographic survey, identify clogging points. Simulate flash floods with rainfall and clogging streams scenarios, mapping and zoning potential area affected by flash floods.

- Enhance the warning and integrate rain radar information and high-resolution satellite clouds into flash flood warning software to estimate rainfall and rainfall proceed in remote areas, especially mountainous areas where do not have detailed rainfall information. Enhance the resolution of the numerical rainfall forecasting model.


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- Develop a flash flood and landslide risk map with 1: 10,000 or 1: 5,000 scales.

- Propose new settlements which are less vulnerable to flash floods.

References1. IMHEN (2010), Final report: flash flood investigation and warning classification for mountainous

area of Viet Nam - Phase 1: Northern mountainous area. (In Vietnamese)2. IMHEN (2010), Report on warnings and investigations to identify the causes of flash floods in Mu

Cang Chai and Muong La during floods from 31/7/2017 -3/8/2017. (In Vietnamese)3. Vietnam Institute of Geosciences and Mineral Resources (2017), Report on the results of the

preliminary survey: Identify causes and assess the present situation of flash floods and initially find for resettlement sites for local communities in the towns of Au Ong and Nam Pa, Muong La district Son La. (in Vietnamese)


CALCULATING AND BUILDING INUNDATION MAPS CORRESPONDING TO FLOOD FREQUENCIES IN GIANH RIVER BASIN

Vu Van Thang(1), Tran Dinh Trong(1), Phung Duc Chinh(1), Jerome Faucet(2)

(1)Viet Nam Institute of Meteorology, Hydrology and Climate change(2)German Red Cross in Viet Nam


Abstract: Gianh is the largest river basin in Quang Binh province with the flood season lasts about four months, from August to November. The number of floods and their magnitude vary widely by the years and from upstream to downstream of the river. This article presents a set of inundation maps corresponding to flood frequencies of 1%, 2%, 5%, 10%, 20% in the Gianh river basin. The results show that flooding happens more frequent in both river banks and downstream areas of Gianh river basin. As Gianh River runs mainly along Tuyen Hoa District, the communes along the river banks of the district are seriously affected by floods. The article also presents a calculated inundation area and inundation rate of the area of districts in the Gianh river basin, corresponding to flood frequencies of 1%, 2%, 5%, 10%, 20%.

Keywords: Flood, flood frequency, inundation maps, inundation area.

1. IntroductionQuang Binh is one of the central coastal

provinces of Viet Nam with very complex climate and terrain. The province is the most affected by natural disasters; tropical cyclones, floods and flash floods occurring with high frequency and severity. Typhoons and floods usually occur from September to December, concentrated in October and November. Tropical cyclones lead to heavy rain and high tides, resulting in floods over the lowland and flash floods over mountainous areas. Other forms of natural disasters such as early floods (“Lũ tiểu mãn” or “Lũ đầu mùa” in Vietnamese) often occur from April to June every year. There are about two or three floods occur in Quang Binh every year, in average.

Natural disasters affect severely socio- economic development and human life. In Viet Nam, prevention of natural disasters and early warning systems for natural disasters are still limited, especially in the provinces that are frequently and directly affected by the disasters such as Quang Binh province.

Therefore, the Viet Nam Red Cross (VNRC) and German Red Cross (GRC) aim at piloting a new approach called Forecast Based Finance (FBF) that uses forecast-based thresholds to automatically release money that pays for pre-planned short-term emergency preparedness actions in the critical window of time after a forecast but before a disaster.

To achieve that goal, the GRC and the Center for Meteorology and Climatology - jointly signed a research contract entitled: “Disasters Profile of Quang Binh Province and Review and Assessment of the Availability and Usage of Early Warning System and Weather Forecasts” with one of the objectives of this contract is to analyze the Disaster Profile of Quang Binh Province with focus on heavy rains and floods.

This article, is extracted from the contract’s outcome, calculates and builds inundation maps corresponding to flood frequencies of 1%, 2%, 5%, 10%, 20% in Gianh river basin. Also to present the inundation area by inundated depths (0-1 m, 1-2 m, 2-3 m, 3-4 m, 4-5 m, 5-6 m, 6-7 m, >7 m) across the basin and the area and inundation rate of the area of districts in the Gianh river basin, corresponding to flood

Correspondence to: Vu Van ThangE-mail: [email protected]


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frequencies of 1%, 2%, 5%, 10%, 20%.2. Data and methodology

Data used in this article are observed water levels of hydrological stations of Dong Tam, Mai Hoa and Tan My with different periods of 1976-2015, 1980-2015, and 1974-2015 respectively.

GIS method combined with survey uses meteo-hydrographical data and topographic maps to identify potential flood areas, and then combined with survey data to develop the flood inundation map for study area. This is a simple method which satisfy the calculation of flood inundation under scenarios with the frequency for Gianh river basin.

At present, the flow measurement data series of the rivers in Quang Binh are neither

complete nor long enough. Therefore, instead of flow data, the highest water levels corresponding to frequencies 1%, 2%, 5%, 10%, 20% and the 10x10 DEM topographic map combined with the survey were used to develop a flood map for the Gianh, Kien Giang river basins with the given frequencies.

The implementing steps are as follows:Step 1: Editing and processing water level

data at hydrological stations in Gianh river basin.

Step 2: Calculate the water level corresponding to the frequency of 1%, 2%, 5%, 10%, 20%.

- The highest water level value in a year was selected basing on the water level datasets at the stations; then

Figure 1. The maximum water frequency at Dong Tam stationin Gianh river

- Creating theoretical frequency lines by Pearson type III (PIII) method for water level at monitoring stations on Gianh river (See Figure 1 for example).

- Based on “theoretical frequency lines” to determine the water level at the stations

corresponding to the frequency of 1%, 2%, 5%, 10%, 20%.

Calculation results of the water levels corresponding to the frequency of occurred floods at the stations are shown in Table 1.

Table 1. Calculated water levels (cm) corresponding to the flood frequencies for stations on Gianh river

Hydrological Stations

Frequency ( P%)1 2 5 10 20

Dong Tam 2082.93 1986.82 1845.76 1723.53 1579.38Mai Hoa 965.31 853.18 703.76 588.76 470.21Tan My 211.60 198.12 179.85 165.46 150.22


Step 3: Develop flood map with frequency of 1%, 2%, 5%, 10%, 20%.

Using digital maps combined with the topographic maps 10x10 DEM to create flooding maps with frequencies of 1%, 2%, 5%, 10%, 20%. Then:

Based on topographic maps to determine the area and level of flooding in flooded areas.

Step 4: Investigating, identifying the flooding traces of floods that have occurred, and the location of flooding in relation to the frequency.

Step 5: Correct the flood maps with the frequencies of 1%, 2%, 5%, 10%, 20% after surveying.3. Results and discussion

3.1. Inundation map corresponding to the frequency of 1%

The calculated results of inundation in Gianh river basin corresponding to flood frequency 1% are presented in Table 2 and Figure 2.

Table 2. The area (km2) and percentages (%) of inundation in the districts of Gianh river basin with a frequency of 1%

No. District Inundated depthTotal 0-1m 1-2m 2-3m 3-4m 4-5m 5-6m 6-7m >7m

1 Bo Trach

60.04 32.06 18.73 6.17 2.36 0.61 0.11 0.00 0.002.83 1.51 0.88 0.29 0.11 0.03 0.01 0.00 0.00

2 Quang Trach

119.90 34.93 15.26 22.27 20.20 15.32 5.95 3.88 2.0919.53 5.69 2.49 3.63 3.29 2.50 0.97 0.63 0.34

3 Tuyen Hoa

49.95 12.34 5.10 6.10 6.13 6.11 4.85 5.42 3.884.35 1.07 0.44 0.53 0.53 0.53 0.42 0.47 0.34

Total 229.89 79.33 39.09 34.54 28.69 22.04 10.91 9.31 5.97

Figure 2. Inundation map corresponding to the frequency of 1% on Gianh river basin

The calculated results of inundation in the Gianh river basin shows that, with the frequency of 1%, about 229.89 km2 in Gianh river basin was

submerged, of which about 79.33 km2, 39.09 km2, and 34.54 km2 were deeply inundated from 0-1 m, 1-2 m, and 2-3 m depth respectively.


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Table 3. The area (km2) and percentages (%) of inundation in the districts of Gianh river basin with a frequency of2%


1 Bo Trach

60.04 32.06 18.73 6.17 2.36 0.61 0.11 0.00 0.002.83 1.51 0.88 0.29 0.11 0.03 0.01 0.00 0.00

2 Quang Trach

119.90 34.93 15.26 22.27 20.20 15.32 5.95 3.88 2.0919.53 5.69 2.49 3.63 3.29 2.50 0.97 0.63 0.34

3 Tuyen Hoa

49.95 12.34 5.10 6.10 6.13 6.11 4.85 5.42 3.884.35 1.07 0.44 0.53 0.53 0.53 0.42 0.47 0.34

Total 229.89 79.33 39.09 34.54 28.69 22.04 10.91 9.31 5.97


The calculated results of inundation in Gianh river basin corresponding to flood frequency 2% are presented in Table 3 and Figure 3.

The calculated result of inundation in the Gianh river basin shows that, with the frequency of 2%, about 180.88 km2 in Gianh river basin was submerged, of which about

62.75 km2, 42.07 km2, and 21.74 km2 were deeply inundated from 0-1 m, 1-2 m, and 2-3 m depth respectively.


The results of flooding in Gianh river basin corresponding to flood frequency of 5% are presented in Table 4 and Figure 4.

The calculated result of inundation in

the Gianh river basin shows that, with the frequency of 5%, about 164.92 km2 in Gianh river basin was submerged, of which about 64.38 km2, 40.05 km2, and 19.78 km2 were deeply inundated from 0-1 m, 1-2 m, and 2-3 m depth respectively.





The calculated results of flooding over Gianh river basin corresponding to the frequency of 10% are presented in Table 5 and Figure 5.

Table 4. The area (km2) and percentages (%) of inundation in the districts of Gianh River basin with a frequency of 5%


1 Bo Trach

48.23 31.33 13.57 2.68 0.56 0.09 0.00 0.00 0.002.27 1.47 0.64 0.13 0.03 0.00 0.00 0.00 0.00

2 Quang Trach

85.31 25.20 20.36 12.98 18.58 5.35 2.20 0.63 0.0113.90 4.10 3.32 2.11 3.03 0.87 0.36 0.10 0.00

3 Tuyen Hoa

31.38 7.85 6.13 4.13 4.13 4.84 2.03 0.96 1.312.73 0.68 0.53 0.36 0.36 0.42 0.18 0.08 0.11

Total 164.92 64.38 40.05 19.78 23.27 10.28 4.24 1.59 1.32

Table 5. The area (km2) and percentages (%) of inundation in the districts of Gianh River basin with a frequency of 10 %


1 Bo Trach

27.14 14.61 10.84 1.39 0.26 0.03 0.01 0.00 0,001.28 0.69 0.51 0.07 0.01 0.00 0.00 0.00 0,00

2 Quang Trach

36.39 10.34 10.85 6.07 6.07 2.32 0.71 0.02 0,005.93 1.68 1.77 0.99 0.99 0.38 0.12 0.00 0,00

3 Tuyen Hoa

15.83 6.20 4.59 1.60 1.60 0.78 0.40 0.20 0,471.38 0.54 0.40 0.14 0.14 0.07 0.03 0.02 0,04

Total 79.36 31.15 26.28 9.06 7.93 3.13 1.12 0.22 0.47


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The calculated results of inundation in Gianh river basin shows that, with the frequency of 10%, about 79.36 km2 in Gianh river basin was


Figure 5. Inundation map corresponding to the frequency of 10% on Gianh River basin


The calculated results of flooding over Gianh river basin corresponding to the frequency of 20% are presented in Table 6 and Figure 6.

Table 6. The area (km2) and percentages (%) of inundation in the districts of Gianh river basin with a frequency of 20 %


1 Bo Trach

19.17 12.44 6.15 0.50 0.06 0.01 0.00 0.00 0,000.90 0.59 0.29 0.02 0.00 0.00 0.00 0.00 0,00

2 Quang Trach

13.11 5.53 5.61 0.89 0.89 0.17 0.02 0.00 0,002.14 0.90 0.91 0.14 0.14 0.03 0.00 0.00 0,00

3 Tuyen Hoa

7.92 4.36 1.78 0.48 0.48 0.26 0.16 0.10 0,290.69 0.38 0.15 0.04 0.04 0.02 0.01 0.01 0,03

Total 40.20 22.33 13.55 1.88 1.43 0.44 0.18 0.11 0.29

The calculated results of inundation in the Gianh river basin shows that, with the frequency of 20%, about 40.20 km2 in Gianh river basin was




3.6. DiscussionAccording to the inundation maps with

different frequencies (Figures 2,3,4,5,6), it can be seen that in Gianh River basin, floods occur frequently in both river banks and downstream areas. The Gianh River runs mainly along Tuyen Hoa (in upstream) and Quang Trach (in downstream) districts, so the communes along the river banks of the districts (Thanh Thach, Le Hoa, Mai Hoa, Tien Hoa, Chau Hoa, Thuan Hoa, Canh Hoa, Quang Lien, Quang Tien, Quang Phuong, Quang Phuc for instant) are seriously affected by floods. Moreover, the high proportion of poor people along the river banks of Tuyen Hoa (even the population density is lower than other districts) increases the vulnerability of people as a result of floods.

In Gianh downstream area, especially in the confluence of Gianh and Con rivers, heavy rain and water flows from upstream can stagnate in low terrain and sunken areas with the consequences of flooding’s in low elevation, low lying terrain (such as Quang Phuong and

Quang Phuc of Quang Trach district). Fortunately, downstream is usually plain and convenient for economic development (with National Highway 1A runs through and near the sea). This leads to a better infrastructure and a higher living standard and education, consequently in higher ability to withstand floods. It means that although the population density is higher, the vulnerability of the flood is lower compared to a long area of both river banks in Tuyen Hoa district. This area is located in Quang Trach district and coastal area of Bo Trach district.4. Conclusions

In Gianh River basin, flooding frequency is high in both river banks and downstream areas. The Gianh River runs mainly along Tuyen Hoa district in upstream, so the communes along the river banks of the district are seriously affected by floods. Moreover, the high proportion of poor people along the river banks of Tuyen Hoa increases the vulnerability of floods.

At Gianh downstream area, especially in the confluence between Gianh and Con Rivers, when heavy raining occurs, water flows from


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upstream will be stagnated at low terrain and sunken area leading to flooded in the low lying terrain areas. However, downstream is usually plain and convenient for economic development, which resulting in a better infrastructure and a higher living standard and education. Consequently, downstream area is in higher ability to withstand floods than in upstream area.

With the frequency of 1%, there is about 229.89 km2 in Gianh river basin was submerged. Having the higher frequency or shorter return period, the submerged area will be lower. There will be about 180.88 km2, 164.92 km2, 79.36 km2, and 40.20 km2 in

submerged in Gianh river basin if the frequency is 2%, 5%, 10% and 20% respectively.

Acknowledgement: This article is part of a research project entitled: “Disasters Profile of Quang Binh Province and Review and Assessment of the Availability and Usage of Early Warning System and Weather Forecasts” jointly signed by the GRC and the Center for Meteorology and Climatology. Authors acknowledge the support and contribution of the Viet Nam Red Cross (VNRC), German Red Cross (GRC), and appriciate to the research team at the Center for Meteorology and Climatology for participating in research, supporting and contributing to the completion of the article.

References1. Binh Thai Hoang (2009), Developing flood maps at downstream area of Nhat Le river system (My

Trung-Tam Lu-Dong Hoi), VNU University of Science.2. Cam Vinh Lai, Hau Xuan Nguyen (2007), Study and implementation on online forecasting technology on

the area and level of flooding in river basins of Central Viet Nam, Viet Nam Institute of Science and Technology.

3. National Hydro-Meteorological Service (2012), Assessment of Historical Flood in October 2010 in Ha Tinh and Quang Binh Provinces for the Prevention and Mitigation of damages caused by Local Floods andsudden change Due to Climate Change.

4. Nguyen Duc Ly, Ngo Hai Duong, Nguyen Dai (2013), Quang Binh climate and hydrology, Hanoi Science and Technology Publishing House.

5. Prime Minister (2014), Decision No. 44/2014 / QD-TTg of the Prime Minister: Detailed regulations on the level of natural disaster risk.

6. Prime Minister (2014), "Decision 46/2014 /QD-TTg of the Prime Minister: Regulations on forecast-ing, warning and communication of natural disasters".

7. Tuan Anh Vu (2013), Thematic reports: “Study on classifying and identifying weather patterns causing heavy rainfall in central and Central Highlands of Viet Nam”. Under the national project: "Study on the construction of 2-3 day heavy rain forecast technology for flood warning in Central Viet Nam".

8. National Center for Hydro- Meteorological forecasting (2006-2016) “Characteristics of meteorology and hydrology”, (collection from 2006-2009).

9. Long Duc Vu, “Research on developing technology for flood warning, forecasting and flooding warning for main rivers in Quang Binh, Quang Tri provinces”, Center Meteorology and Hydrology.


CLIMATE CHANGE VULNERABILITY ASSESSMENT FOR AGRICULTURE SECTOR IN TUYEN QUANG PROVINCE

Nguyen Xuan Hien(1), Pham Tien Đat(1), Doan Thi Thu Ha(1, 2), Nguyen Thi Phuong(1), Dang Linh Chi(1)

(1)Viet Nam Institute of Meteorology Hydrology and Climate Change(2)Sejong University, Korea


Abstract: Climate Change (CC) has significant impacts to socio-economic development in Viet Nam and agricultural is one of the most affected sectors. The most impacted provinces are those where economic activities are highly dependent on ecosystem services such as Tuyen Quang. This study applies vulnerability assessment framework proposed by Allison et al (2009) and the unequal weights methodology developed by Iyengar and Sudarshan (1982) to assess climate change vulnerability for agriculture sector in Tuyen Quang province. The results show that, in the 21st century, Son Duong and Na Hang districts are highly vulnerable to climate change while Tuyen Quang city is less vulnerable than other districts. This study presents useful results to help local governments and communities to respond to climate change impacts in the future.

Keywords: climate change, agricultural, impact, vulnerability assessment.

1. IntroductionMany studies have shown that vulnerability

to climate change in developed and developing countries have significant differences (IPCC, 2001). Poor countries, developing countries, or small island states are more vulnerable to the adverse effects of climate change such as extreme weather events than developed countries (UNDESA, 2010).

The study of climate change vulnerability should base on a full consideration of major components: exposure, sensitivity and adaptive capacity [IPCC, 2001; Heltberg et al., 2009; Moss et al., 2002; Polsky et al., 2007]. Vulnerability assessments usually aim to answer the following questions: who and what is vulnerable, what are the underlying reasons, how to respond to the problems to reduce climate change impacts and increase adaptive capacity. However, the identification of indicators to quantify vulnerability are sometimes difficult and the available dota is limited.

To assess climate change vulnerability, many

studies have been using “vulnerable index” approach in which an index was conducted based on several set of indicators to represent the vulnerability. This method allows a quantitative assessment of vulnerability and a relative comparison between different regions [Torresan et al., 2008, Hahn et al., 2009]. Torresan et al., (2008) applied the DIVA tool (Dynamic International Vulnerability Index) to assess the vulnerability of Venetia Beach (Italy) based on two sets of the coastal vulnerability indicators: (i) topographic and slope; (ii) geomorphology; (iii) vegetation distribution, and (iv) population and population density. However, the indicators used to assess were mainly natural vulnerability index, not pay much attention on socio-economic vulnerability index. Hahn et al. (2009) used a set of Livelihood Vulnerability Index (LVI) to assess the impact of climate change through the impact assessment of natural disasters and the variability between individual populations in two counties includes: Mabote, Moma in Mozambique. However, in this study, the weight of all indicators is considered

Correspondence to: Nguyen Xuan HienE-mail: [email protected]


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equal when the evaluation affected the results of the study. Alex de Sherbinin et al. (2007) base on climate change scenarios combined with bottom-up vulnerability assessment approaches to study vulnerability in the three cities including Mumbai, Rio de Janeiro and Shanghai.

The Intergovernmental Panel on Climate Change (IPCC) has developed definitions of vulnerability based on scientific studies in the world over many years. In 1990, the first IPCC’s Assessment Report on Climate Change (FAR 1990) identified vulnerability as the inability to cope with the consequences of climate change and sea level rise. In 1995, the second IPCC’s Assessment Report (SAR 1995) identified vulnerability as the degree that climate change could cause harm or disadvantages to the system. The vulnerability does not only depend on the susceptibility of the system but also on the adaptive capacity of the community with new climatic conditions and are considered as the remaining impacts of climate change after adaptive solutions implemented (Downing, 2005). This definition includes: exposure, susceptibility, resilience of the system to climate change.

The Third IPCC Report on Climate Change (TAR 2001) explained that vulnerability is the degree to which a system (natural or human) is susceptible to, or unable to cope with, adverse effects of climate change. Vulnerability is a featured function of the intensity, speed of climate change when the system is exposed, including susceptibility and adaptability. This concept is used in future IPCC’s reports (AR4, AR5).

This study conducted a vulnerability assessment for Tuyen Quang - a mountainous province in northern Viet Nam (Figure 1). The natural area of the province is 5,868 km2, accounting for 1.78% of the country area. Agricultural sector plays an important role in the socio-economic development of the province. Hence, climate change vulnerability assessment may provide local government and other agencies having an overview of how climate change would affects this area.

2. Methodology and procedure of climate change vulnerability assessment in the agriculture sector

2.1. DataThe vulnerability assessment is based upon

data from the agricultural sector, socio-economic data including data from forestry and fishery that have been collected from sources such as: statistical yearbook 2015 of Tuyen Quang province, the analysis of climate change impacts in Tuyen Quang with scenarios greenhouse gas emissions RCP 4.5 extracted from the climate change scenarios for Viet Nam and for the districts Tuyen Quang [MONRE, 2016; IMHEN, 2011].2.2. Methodology

This study recommends using the concept of vulnerability (to climate change) of the IPCC (2007). Vulnerability to climate change is defined as “the degree to which geophysical, biological and socio-economic systems are susceptible to, and unable to cope with, adverse impacts of climate change, including climate variability and extremes”.

The term “vulnerability” may therefore

Figure 1. Administrative map of Tuyen Quang Province


refer to a function of three main components: “Exposure” (E), “Sensitivity” (S) and “Adaptive Capacity” (AV).

V = f(E, S, AC) (1)where: E=“The nature and degree to which

a system is exposed to significant climatic variations”; S=“the degree to which a system is affected, either adversely or beneficially, by climate variability or change”; AC=“The ability of a system to adjust to climate change (including climate variability and extremes) to moderate potential damages, to take advantage of opportunities, or to cope with the consequences”.

Based on the IPCC’s vulnerability concept, the study proposes a vulnerability assessment for Tuyen Quang province using a relative method (Gleick, 1998; IPCC, 2007, Keskinen, 2009; Babel and Wahid, 2009).

The vulnerability is evaluated by using factors/indicators causing vulnerability, normalizing indicators and then calculating weights for each indicator. Finally, result is an average quantitative value allowing a relative comparison between districts in the province, which will be mapped. Vulnerability assessment’s framework proposed by Allison et al. (2009) assesses exposure, sensitivity, potential impacts and adaptation capacity. The functional relationship to normalize data and then applying the method of unequal weights developed by Iyengar and Sudarshan (1982) was used to calculate the weight indices.

Steps for CVI calculations are shown below:Step 1: Data normalizationData normalization is to convert the

collected raw data with different units to the dimensionless value ranging from 0 (minimum value) - 1 (maximum value) to be able to compare between administrative units. If higher the value of sub-index more will be the vulnerability of the region to climate change, we apply the following formula:

If vice versa, we apply the formula:

where: xij is normalized value; Xij is raw data of the ith sub-index at jth administrative unit; Max{Xij} and Min{Xij} is the maximum and minimum values of ith sub-index, respectively.

Step 2: Calculate weights This study chose the unequal weight

method proposed by Iyengar and Sudarshan (1982). A brief summary of this method is given below:

The weights of each sub-index is determined by:

( )j

j

CW

Var x= (3)

where: wj: weight of the sub-index j of E, S and AC; Var(xj) is variance of sub-index j determined by: ( )

( )

2

1 1

n ij

xjj

x xVar

n=

−=

−∑

C is normalizing constant and is determined by:

( )1

1m

jj

CVar x=

= ∑

(4)where: m: the number of sub-indices;Note that the sum of weights of each

sub-index group must equal 1.( )1

, , 1Kjj

W E S AC=

=∑0 <wj< 1

After identifying the weights, values of each sub-index group are determined by:

1

NI J ijJ

M w x=

=∑ (5)i = 1 ÷ m, the number of administrative units.where: Mij: value of sub-index group j of

administrative unit i; Wj: weight of sub-index j.Step 3: Construction of vulnerable index (VI)After identifying the weights and the values

of each sub-index group, we calculate the value of each major component (E, S and AC) for each administrative unit. For example, the exposure component is determined by:

( )1/

i

ni i Mi

E M m m=

= ×∑ Where: Ei is value of exposure of administrative

unit ith, mMi is the number of sub-indices of Mi and m the total number of sub-index groups.

Repeat the same calculation for S and AC. Finally, the vulnerable index (of each districts) is defined as:

(1)

(2)

(6)

-1

j


79

( )

3i i i

i

E S ACV

+ +=

3. Results and discussionsIdentifying vulnerable factors is an important

step to determine the relationships between the factors (presented as sub-indices) and vulnerable components so that the correct standardized function will be applied. Sub-index group will be determined as a basis for calculating the value of the main component E, S and AC. Table 1 below lists the sub-indices (in groups) of the main components with the trend of relations with vulnerability index VI. The

exposure-index group such as climate fluctuations (rainfall - E1, temperature - E2) is determined from the climate change scenario for Tuyen Quang (RCP Scenario 4.5); The sensitive-index group (structure and agroforestry area - S1, socio-economic - S2, the area of food crops and industry - S3, livestock - fishery - water demand - S4) is determined from the statistics data. The adaptation-index group (Agricultural, Forestry, Aquaculture - AC1, Education - Health - Infrastructure - AC2) is determined from statistics data.

Table 1. Indices and relationship with CVI

No Components Indices Relationship with CVII Exposure1 Climate

variability - indices of

precipitation

Minimum changes of precipitation in the winter ↓2 Maximum changes of precipitation in the winter (E1-2) ↑3 Minimum changes of precipitation in the summer (E1-3) ↓4 Maximum changes of precipitation in the summer (E1-4) ↑5 Minimum changes of annual precipitation (E1-5) ↓6 Maximum changes of annual precipitation (E1-6) ↑7 Minimum changes of maximum daily precipitation (E1-7) ↓8 Maximum changes of maximum daily precipitation (E1-8) ↑9 Minimum changes ofmaximum 5-day

average precipitation (E1-9)↓

10 Maximum changes ofmaximum 5-day average precipitation (E1-10)

↑

11 Climate variability - indices of

temperature(E2)

Minimum changes of minimum temperature (E2-1) ↓12 Maximum changes of minimum temperature (E2-2) ↑13 Minimum changes of maximum temperature (E2-3) ↓14 Maximum changes of maximum temperature (E2-4) ↑15 Minimum changes of average temperature

in the summer (E2-5)↓

16 Maximum changes of average temperature in the summer (E2-6)

↑

17 Minimum changes of average temperature in the winter (E2-7)

↓

18 Maximum changes of average temperature in the winter (E2-8)

↑

19 Minimum changes of annual temperature (E2-9) ↓20 Maximum changes of annual temperature (E2-10) ↑

(7)


II Sensitivity S1 Agricultural

indices (S1)Percentage of agricultural land (S1-1) ↑

2 Percentage of forestry land (S1-2) ↑3 Structure of agricultural land (S1-3) ↑4 Structure of forestry land (S1-4) ↑5 Social-

Economy indices (S2)

Percentage of women (S2-1) ↑6 Population density (S2-2) ↑7 Percentage of rural population (S2-3) ↑8 Number of kindergarten (S2-4) ↑9 Number of poverty villages (S2-5) ↑

10 Percentage of families to live in poverty (S2-6) ↑11 Poverty of families to live in poverty threshold (S2-7) ↑12 Food and

Industrial crops indices

(S3)

Acreage of food crops (S3-1) ↑13 Acreage of potatoes and wheat (S3-2) ↑14 Acreage of sugarcane (S3-4) ↑15 Acreage of tea (S3-5) ↑16 Acreage of orange (S3-6) ↑17 Livestock -

Aquaculture - water

demand indices (S4)

Number of cattle (S4-1) ↑18 Number of poultry (S4-2) ↑19 Acreage of aquaculture (S4-3) ↑20 Acreage of aquaculture development (S4-4) ↑21 Water demand of early century (S4-5) ↑22 percentage of changes of water demand (S4-6) ↑III Adaptive capacity (AC)1 Commercial

activities (AC1)

Number of operations (AC1-1) ↓2 Number of farms (AC1-2) ↓3 Agricultural manufacturing values (AC1-3) ↓4 Food-crop yields (AC1-4) ↓5 Potatoes and wheat yields (AC1-5) ↓6 Sugarcane yield (AC1-6) ↓7 Tea yield (AC1-7) ↓8 Orange yield (AC1-8) ↓9 Forestry manufacturing values (AC1-9) ↓

10 Aquaculture manufacturing values (AC1-10) ↓11 Aquaculture yield (AC1-11) ↓12 Development of aquaculture yield (AC1-12) ↓13 Cattle yield (AC1-13) ↓

No Components Indices Relationship with CVI


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14 Education - Health care and Infra-structure

indices (AC2)

Number of teachers (AC2-1) ↓15 Number of kindergarten schools (AC2-2) ↓16 Cultural families (AC2-3) ↓17 Health care development (AC2-4) ↓18 Total of staff working in health care (AC2-5) ↓19 Percentage of doctors (AC2-6) ↓20 Length of road (in km) (AC2-7) ↓21 Number of female owner (AC2-8) ↓22 Acreage of forest (AC2-9) ↓23 Index of forestry development (AC2-10) ↓

The sub-index group Ei,j, Si,j, and ACi,j for each administrative unit at district level in Tuyen Quang province is calculated and normalized according to formula (1) and (2) respectively.

The weights of each sub-index is calculated according to (3) and (4). Table 2 shows equations the results of E, S and AC indexes in Tuyen Quang province.

Table 2. Values of groups of each component

No Units E1 E2 E3 S1 S2 S3 S4 AC1 AC21 Tuyen Quang City 0.570 0.463 0.205 0.257 0.626 0.036 0.138 0.820 0.2852 Na Hang 0.640 0.193 0.135 0.495 0.372 0.136 0.377 0.833 0.6603 Chiem Hoa 0.446 0.370 1.000 0.687 0.529 0.479 0.641 0.609 0.5074 Ham Yen 0.412 0.408 0.452 0.643 0.409 0.689 0.696 0.410 0.4895 Yen Son 0.513 0.496 0.000 0.687 0.516 0.642 0.703 0.354 0.432

6 Son Duong 0.341 0.913 0.355 0.648 0.553 0.680 0.703 0.397 0.3937 Lam Binh 0.195 0.333 0.000 0.434 0.341 0.052 0.564 0.894 0.718

The results of E, S, AC calculation of Tuyen Quang administrative units when the weights of each index is calculated according to

equations (6). Table 3 shows the results of E, S and AC in indexes Tuyen Quang province.

No Units E S AC VI1 Tuyen Quang City 0.506 0.334 0.233 0.0612 Na Hang 0.219 0.218 0.386 0.3853 Chiem Hoa 0.683 0.614 0.457 0.3884 Ham Yen 0.729 0.716 0.552 0.5395 Yen Son 0.526 0.594 0.146 0.4846 Son Duong 0.568 0.303 0.389 0.1247 Lam Binh 0.607 0.722 0.394 0.509

Table 3. Values of E, S, AC and Vulnerability index VI

No Components Indices Relationship with CVI


The projection of climate change vulnerability indexes (E, S, AC and VI) of agricultural sector by the end of the XXI century calculated for the districts and city of Tuyen Quang province have been normalized once again then classified into

4 levels including: very high, high, medium and low based on the assessment results. Figure 2 shows the maps of exposure, sensitivity, adaptive capacity and climate change vulnerability of agricultural sector of Tuyen Quang province.

Figure 2. Vulnerability to climate change map for agricultural sector in Tuyen Quang province at the end of century: (a) Exposure; (b) Sensitivity; (c) Adaptive capacity and (d) Vulnerability to

climate change

(a) (b)

(c) (d)


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The results show that, Son Duong district is most exposed to climate change impacts. The district is located in the southern area of Tuyen Quang province with large acreage of agricultural and forestry lands thus would be heavily affected by natural disasters. In contrast, Lam Binh district is the least exposed one. This district has high topography that lead to very minor effect of flooding. Other districts that have high level of exposure are Chiem Hoa, Yen Son and Tuyen Quang city. The sensitivity to climate change in agriculture depends on indices of land use, rural population, livestock-cultivation and water demands for agricultural activities. The results show that, by the end of this century, Tuyen Quang city is least sensitive to climate change compared to the rest of other districts and followed by Na Hang. In contrast, Ham Yen,Yen Son and Son Duong are among highest sensitivity districts. The adaptive capacity of administrative units of Tuyen Quang province is assumed unchanged in the future. Yen Son, Son Duong and Ham Yen districts are the highest adaptive capacity. Those districts have active agricultural and other social-economic activities. Tuyen Quang city and Chiem Hoa district are both highly adaptive to climate change. While Tuyen Quang is strong at economic, social and cultural indicators, Chiem Hoa district has a strong position in cultivation and forestry, especially food crops and industrial crops such as sugarcane. Adaptive capacity of Na Hang district and Lam Binh district are low compared to other districts in the province. These areas are often subjected to many natural disasters. Therefore, agricultural activities are difficult that results in low productivity and crop yields. In addition, the economic, social and cultural

indicators of these areas are relatively low in comparison with other areas in the province.

The results of vulnerability to climate change in agriculture show that Tuyen Quang city is less vulnerable than other districts in the province. Son Duong, Chiem Hoa and Yen Son districts are high vulnerabe.4. Conclusions and Recommendations

This article presents a method for calculating the vulnerable index (VI) for Tuyen Quang province. Data are also collected and combined with results from model calculations to ensure the accuracy. The results of VIs are logical and scientific. The calculations are presented in detail and clearly, not too complicated to implement. This provides a useful tool to help local authority to calculate and assess impacts of climate change not only for agriculture but also for other sectors.

The article also points out that data (completeness and reliability) play an important role for the calculation of VI. Therefore, statistical data should be updated and supplemented (at least every 5 years). Indicators of other natural disasters (floods, landslides, droughts,... should also be considered to have a more comprehensive assessment. In addition, recent studies have shown the need to integrate climate change into socio-economic development planning. Especially, the integration of climate change into development planning processes (mainstreaming) through strategic environmental assessments at local level can be very beneficial. This contributes to enhance the autonomy of local prevention against the adverse effects of climate change.

References1. Allison et al. (2009), Vulnerability of national economies to the impacts of climate change on

fisheries, FISH and FISHERIES, Blackwell Publishing Ltd.2. Dow, K. and Downing, T.E. (2005), The Atlas of Climate Change:Mapping the World's Greatest

Challenge, Berkeley: University of California Press.3. Hahn, M.B., Riederer, A.M. and Foster ,S.O. (2009), The Livelihood Vulnerability Index: Apragmatic

approach to assessing risks from climate variability and change, A case study in Mozambique,


Global Environmental Change.4. Heltberg, R., Siegel,P.B. and Jorgensen, S.L. (2009), "Addressing human vulnerability to climate

change: Toward a ‘no-regrets’ approach", Global Environmental Change, 19(1), 89-99.5. IMHEN (2011), A guidance for climate change impact assessment and adaptation measures,

Viet Nam Publishing House of Natural Resources, Environment and Cartography, Hanoi (In Vietnamese).

6. IPCC (1990), Climate Change 1990: Impacts Assessment of Climate Change. Contribution of Working Group II to the First Assessment Report of the IPCC, Australian Government Publishing Service, Canberra, Australia, 294 pp.

7. IPCC (1995), Climate Change 1995: Impacts, Adaptations and Mitigation of Climate Change: Scientific-Technical Analyses, Contribution of Working Group II to the Second Assessment Report of the IPCC.

8. IPCC (2007), Climate Change 2007: Impacts, Adaptation and Vulnerability.Contribution of Working Group II to the Fourth Assessment Report of the IPCC, Cambridge University Press, Cambridge, UK, 976pp.

9. IPCC (2001), Climate Change 2001: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the IPCC, Cambridge University Press, Cambridge, 1032pp.

10. MONRE (2016), Climate change and sea level rise scenario for Viet Nam, Viet Nam Publishing House of Natural Resources, Environment and Cartography, Hanoi (In Vietnamese).

11. Moss, R.H., Malone,E.L. and Brenkert, A.L. (2002), Vulnerability to climate change:A quantitative approach, Joint Global Change Research Institute.

12. Polsky, C., Neff,R. and YarnalB. (2007), “Building comparable global change vulnerability assessments: the vulnerability scoping diagram”, Global Environmental Change, 17(3-4), 472-485.

13. Sherbinin,A., Schiller,A. and Pulsiphe,A. (2006), “The vulnerability of global cities to climate hazards”, Environment & Urbanisation, (12), 93-102.

14. Torresan, S., Critto, A., Valle, M.D, Harvey, N. and Marcomini, A. (2008), Assessing coastal vulnerability to climate change: Comparing segmentation at global and regional scales, Sustainability Science.


85

POLICIES TO PROMOTE SUSTAINABE WATER RESOUCES MANAGEMENT IN VIET NAM - AN IN-DEPTH ANALYSIS

Le Ngoc CauViet Nam Institute of Meteorology, Hydrology and Climate change


Abstract: The importance of water for sustaining country’s growth while improving public health and the environment cannot be understated. While Viet Nam uses only about 10% of the volume of available water on a national basis, regional and especially seasonal shortages are major limiting factors for industrial and agricultural development. Vulnerable ecosystems such as the Mekong River Delta and Red River Delta are seeing lower flows, causing shortages of water supply and saline water intrusion, disrupting fisheries and impacting the quality of irrigation supplies. The delicate balance of upland ecosystems and crops is being affected to a greater extent by more severe weather patterns and flooding. These factors are clearly unfavorable for rural development and poverty reduction. The Government of Viet Nam (GoV) is committed to address these complex water sector issues. A series of water resources management related legal policies and documents have been promulgated and implemented in the past decade. This paper presents an overview of legal frameworks and policies promulgated and implemented by GoV to promote sustainable water resources management in Viet Nam. An in-depth analysis of the water resources management related legal framework and policies was conducted to get an insight into the coherence of the policies and impacts brought by the implementation of the promulgated policies.

Keywords: sustainable water resources management, water saving and efficiency, climate change resilience, Viet Nam.

1. IntroductionDue to the rapid economic development and

urbanization in Viet Nam, water resources are under risk due to several factors of which many are inter-connected: Rising demand for fresh and drinking water in the course of urbanization and industrialization, climate change impacts, upstream development and construction (hydroelectric dams, deforestation). Lower water flows and shrinking groundwater level are occurring in key river basins, such as Red River Delta and Mekong River Delta, causing shortage of water supplies and saline water intrusion and impacting agricultural production. The GoV has well recognized the importance of water in sustaining socio-development and maintaining public health. A series of water resources management legal-binding policies

has been developed and adopted to promote sustainable water consumption in Viet Nam.

The first Water Resources Law which came into force in 1998 has become obsolete under fast changing socio-economic development and climate change conditions. Recognizing that a comprehensive legal framework is of vital important to materialize a sustainable water resources management, the GoV has developed and enacted a new Water Resources Law 17/2012/QH13 in 2013, the highest legal document in the water resources management field. The law come into effect in January 1st, 2013 replacing the 1998 Water Resources Law and serving as a fundamental legal framework for the development and adoption of under-law documents and policies on water resources management. The Law is an important milestone and a legal document that promotes climate change resilience and adopts integrated water management approaches for sustainable water

Correspondence to: Le Ngoc CauE-mail: [email protected]


resources management. Following the adoption of the Water

Resources Law, a series of legal documents and policies promoting sustainable water resources management have been issued to replace the previous documents which were not suitable in the current context, especially in the context of climate change. The scope of water resources management has been widened and economic tools are incorporated. Water resources management does not longer only focus on quality and quantity issues but includes issues such as the management of riverbeds, riversides and riverbanks, the development of economic tools and measures to promote effective water resources management and sustainable water use.

Water resources management plays an important role for economic growth, public health, environmental protection and the sustainable development of the country. Viet Nam uses only about 10% of its available water resources on the national level. However seasonal water shortages are a major barrier for industrial development and agricultural production. Vulnerable river basins such as the Mekong River Delta and Red River Delta are seeing lower flows, causing shortages of water supply and salt water intrusion, disrupting fisheries and impacting the quality of irrigation systems. Ecosystems and agricultural land will be seriously affected by the extend and severe extreme weather events such as flooding and prolonged draught. These factors are clearly unfavorable for rural development and poverty reduction.

The Government of Viet Nam is committed to address these complex water sector issues. A series of water resources management related legal documents and policies have been promulgated and implemented in the past decade. This paper presents an overview of legal framework and policies promulgated and implemented by GoV to promote sustainable water resources management in Viet Nam. An in-depth analysis of the water resources management related legal framework and policies was conducted to

get insight into the efficiency and positive impacts brought by the implementation of the promulgated policies.2. Background information

In 2012, the GoV enacted the Water Resources Law 17/2012/QH13 to replace the Water Resources Law that has been implemented since 1998. The Water Resources Law 17/2012/QH13 is the highest legal document in the water resources field which takes effect in January 1st, 2013, laying out a fundamental foundation for legal documents on water resources management. The Law is a very important milestone, a policy response to climate change impacts and resilience programming which adopts integrated water management approaches and sustainable water resources management.

Pursuant to the new Water resources Law, a number of legal-binding documents and policies on water resources management have been issued to replace the preceding documents that have become unsuitable in ever-changing socio-economic development, especially in the context of climate change. A notable aspect of the current water resources management related policies is that the subjects of water resources management are expanded and economic tools are applied in water resources management. Most important perspective is that subjects of water resources management are no longer confined to only the quality and quantity of water in rivers, but that have been extended to the management of riverbeds, riversides and riverbanks, as well as setting up the economic tools and measures in water resources management with the ultimate goal of realizing a sustainable water resources management.

Integrated water resources management has become an overarching viewpoint of Viet Nam and has been shown throughout the National Strategy on Water Resources (Prime Minister Decision 81/2006/QĐ-TTg): “Management of water resources must be implemented in an integrated and unified manner on a river basin basis. The water use structure must be consistent with the transformation of economic structure


87

Figure 1. Legal framework of water resources management in Viet Nam

in the period of enhancement of national industrialization and modernization; water resources must be developed, exploited and used in sustainable, economically efficient, integrated and multi-purpose manner. Water in production must be considered as economic goods; subsidised system should be soon eliminated; activities in water resources protection and development and in water service provision should be performed with the participation of all social and economic sectors.”

National action plan on strengthening the integrated management, protection and use of water resources towards the 2014-2020 period was enacted with the Decision 182/QD-TTg dated January 23rd 2014 in order to make sure that water resources management, exploitation, use and protection shall be implemented in an integrated, comprehensive and long-term manner to ensure the social security and national defense under the pressure of climate change, sea level rise and water resources depletion.

As shown in Figure 1, after enacting the Water Resources Law 17/2012/QH13 in 2013, the GoV has been promulgated and implemented, a number of under-law policies guiding detail implementation of the law. Notably, the following policies have been issued to promote sustainable water resources management.

• Decree 201/2013/ND-CP dated November 27, 2013, detailing the implementation a number of articles of the Water Resources Law.

• Decree 142/2013/ND-CP on providing for sanction of administrative violations in domain of water resources and minerals exploitation.

• Decree 43/2015/ND-CP on the establishing and managing the water protection corridor.

• Decree 54/2015/ND-CP regulating incentives for water saving and efficient activities.

• Decree 60/2016/ND-CP regulating some conditions for trading investment in sector of natural resources and environment.

• Decree 154/2016/ND-CP on environmental protection fee for wastewater.

• Decree 33/2017/ND-CP regulating on sanctioning administrative violations in the field of water and mineral resources.

• Decree 82/2017/ND-CP regulating the method for calculating and charges for granting water entitlements.

Within its mandates, functions and responsibilities, MONRE has also issued a number of documents on guiding/detailing the implementation of the Water Resources Law. MONRE, at the same time, has been developing, and finalizing many legal documents and expects to complete a comprehensive legal framework in 2020 according to direction of Law on Water Resources 2012 and Resolution 24/NQ-TW of


Central Party Steering Committee on proactively responding to climate change, and strengthening natural resources management, and environmental protection. Notably, the following circulars have issued and implemented.

• Circular 27/2014/TT-BTNMT regulating registration for groundwater extraction, form of application, permit, contents of scheme and report in dossier for issue, extension, modification, re-issue of water resource permit.

• Circular 42/2015/TT-BTNMT regulating technique for water resources planning.

• Circular 24/2016/TT-BTNMT regulating the identification and public of protection zone of domestic intake source.

Besides the above-mentioned policies, the following circulars will be developed and adopted in between 2017-2020:

• Circular on protection of river bed, bank and plain.

• Circular regulating content, form of statistics and reports on water resources inventory

• Circular on content, forms for investigation, content of report and procedure for investigating actual conditions of water resources exploitation and use, wastewater discharge into river.

• Circular regulating contents, regulations of water resources monitoring.

• Circular regulating data sets, data formats on water resources.

• Guiding circular on artificial supply of groundwater for each regions.

• Circular on contents, forms for the statistic and report of water resources use.

• Guiding circular on artificial supplement of groundwater for each regions.

• Joint circular between MONRE and MOF giving guidance about the management and use of budget for the water resources investigation, planning, management and protection.

• Joint Circular between MONRE and MOF about revising decision 59/2006/QD-BTC regulating the regime of charge and fee to collect, remittance, management and use fee.

In addition to the policies that directly address water resources management and water environment protection, the GoV also prepared and adopted inter-reservoir operation

procedures for large river basins. Until now, the inter-reservoir operation procedures have been developed and put into operation for most of the 11 river basins that are required to have the inter-reservoir operation procedures. With the policy promulgated, the rules for operating reservoirs are established, and different interests, e.g. electricity generation from hydropower plants and irrigation for agricultural production, are adequately taken into consideration.3. Discussion

The discussion will focus on the following aspects of the policies that have been developed and adopted by the GoV: (i) institutional framework of water resources management in Viet Nam; and (ii) sustainable water consumption promotion.

Institution arrangement for water resources management was explicitly stipulated at the Water Resources Law. The state management of water resources is uniformly doneby the Government. The Ministry of Natural Resources and Environment (MONRE) takes responsibility in implementation of state management on water resources, management on river basin in nationwide. In terms of sustainable water resources management, MONRE’s key responsibilities, as stipulated under Water Resources Law, are: (i) development of water efficacy and saving models, promotion of water saving technologies; (ii) coordination of water resources uses in inter-provincial river basins; (iii) monitoring and inspecting the quantities and quality of water resources, water resources exploitation and use, and discharge of wastewater into inter-provincial water resources.

With regards to the promotion of sustainable water consumption, it is notable that relevant policies promulgated by the GoV are coherent and converging on this issue. First, a policy incentivizing water saving and water recycling activities have been issued in 2015 (Decree 54/2015/ND-CP). For the first time, a legal-biding policy regulating incentives for water saving and efficiency was issued and implemented. The Decree defines a wide range in potential water savings activities, including water reuse/


89

recycling, reduction in water consumption, rainwater harvesting, and desalination of brackish and salt water. Potential incentives include preferential loans, tax reductions and tax waivers. Organizations that could benefit from incentives include large industrial enterprises, small businesses, farmers, and individual households.

In addition to policies and incentive mechanisms that promote water efficiency in industrial and commercial uses, the GoV has also taken concrete action promoting development of small irrigation systems, infield irrigation, and more advanced and efficient irrigation systems with the ultimate goal of promoting sustainable water resources consumption for agricultural activities. At ministerial level, MARD minister in May 2015 issued Decision 1788/QĐ/BNN-TCLL approving Action Plan of Advanced and Efficient Upland Plant Irrigation. The Action

Plan summarizes numerous steps that should be taken to advance more effective irrigation, in particular for upland crop irrigation. It calls for improving policy and institutional frameworks, launching pilot projects, advancing scientific understanding, providing training and outreach, encouraging international cooperation, and other topics.

To foster water saving and efficient in irrigation, a Prime Minister Decree is planned to be issued in 2017, setting the stage for actions to advance more efficient irrigation in a manner that supports the objectives of Decree 54 within the context of the Government’s program on agricultural restructuring and rural development. The Decision is expected to establish basic financial incentives (e.g. subsidized equipment purchase or favorable interest rates on loans), eligibility criteria, and program structures for applicants and the Government.

References1. Circular 27/2014/TT-BTNMT regulating registration for groundwater extraction, form of

application, permit, contents of scheme and report in dossier for issue, extension, modification, re-issue of water resource permit (In Vietnamese).

2. Circular 42/2015/TT-BTNMT regulating technique for water resources planning (In Vietnamese).3. Circular 24/2016/TT-BTNMT regulating the identification and public of protection zone of

domestic intake source (In Vietnamese).4. Decision 81/2006/QD-TTg approving the national strategy on water resources to 2020 (In

Vietnamese).5. Decision 1788/QD/BNN-TCLL approving action plan of advanced and efficient upland plant

irrigation (In Vietnamese).6. Decree 201/2013/ND-CP detailing the implementation a number of articles of the Law on Water

Resources (In Vietnamese).7. Decree 142/2013/ND-CP regulating sanction of administrative violations in domain of water

resources and minerals exploitation (In Vietnamese).8. Decree 43/2015/ND-CP on the establishing and managing the water protection corridor (In

Vietnamese).9. Decree 54/2015/ND-CP regulating incentives for water saving and efficient activities. (In Vietnamese)10. Decree 60/2016/ND-CP regulating some conditions for trading investment in sector of natural

resources and environment (In Vietnamese).11. Decree 154/2016/ND-CP on environmental protection fee for wastewater (In Vietnamese).12. Decree 33/2017/ND-CP regulating on sanctioning administrative violations in the field of water

and mineral resources (In Vietnamese).13. Decree 82/2017/ND-CP regulating the method for calculating and charges for granting water

entitlements (In Vietnamese).14. LawNo. 17/2012/QH13: Law on Water Resources (In Vietnamese).


APPLICATION OF AIRLIFT MEMBRANE BIOREACTOR FOR SLAUGHTERHOUSE WASTEWATER TREATMENT: 20 M3/DAY PILOT

STUDY IN HA NOI, VIET NAM

Do Tien Anh(1), Huynh Thi Lan Huong(1), Pham Hai Bang(2)

(1)Viet Nam Institute of Meteorology, Hydrology and Climate Change(2)Ministry of Natural Resources and Environment


Abstract: Untreated wastewater from slaughterhouses has been contributing to the contamination of Day River due to its high concentration of COD, BOD, total nitrate (TN) and total phosphate (TP). Centralized wastewater treatment is not a good option at present due to lack of wastewater conveyance infrastructure and finance. On-site wastewater treatment has been emerging a better choice. This study evaluates an onsite wastewater treatment system using an airlift membrane bioreactor for a slaughterhouse in a suburb of Ha Noi. The system was designed to treat 20 m3/day slaughterhouse wastewater. Wastewater from the Slaughterhouse contains 1060 ± 458 mg/L COD, 1060 ± 458 mg/L BOD and 451 ± 133 mg/L TN. Anaerobic and anoxic tanks were operated at the mixed liquor volatile suspended solid (MLVSS) of 1,500 mg/L. Cross-flow velocity, airlift flow rate and the transmembrane pressure (TMP) were maintained at 2 bar. The removal efficiencies of COD, TN were 89.1±4% and 85±8.7%, respectively. The results proved that AL-MBR could work well at pilot scale and be promising for upscaling along Nhue - Day River in future.

Keywords: wastewater, slaughterhouse, Nhue - Day River, membrane, airlift.

1. IntroductionNhue - Day River has been suffering from

severe contamination due to human activities along its basin. The average concentration of organic matters in Nhue - Day River has been reported 2.2-9 times higher than Viet Nam´s discharge regulation standard (QCVN 08-MT: 2015/BTNMT) (Viet Nam Institute of Water Resources Planning, 2016). One of the sources which contribute to the pollution of the river is untreated wastewater from slaughterhouses located along the River's basin. Untreated wastewater from slaughterhouses contains high concentration of COD, BOD, total nitrogen (TN) and total phosphate (TP). Do et al. (2016), reported that the average concentration of COD, BOD, TN and TP in SHWW in Viet Nam was 1697±317 mg/L, 891±137 mg/L, 246±65 mg/L and 1,164 mg/L, respectively. Wastewater from the slaughterhouses along the basin is currently

not adequately treated. Untreated slaughterhouse wastewater (SHWW) could cause pollution of natural reservoirs, environment, spreading diseases and health problems for residents along the riverside. With the rapid population growth along the riverside, these problems would become worse. The lack of conveyance infrastructure and finance are considered as major challenges for treating SHWW by centralized wastewater treatment systems in the basin in the near future. On-site treatment is being mentioned as a better option at this moment. However, the slaughterhouses along the basin are currently not equipped with the adequate wastewater treatment system.

Membrane bioreactors (MBR) has emerged as a popular application for onsite wastewater treatment (Choi et al., 2002; Daigger et al., 2005; Asatekin et al., 2006). The major advantages of MBR are: (i) efficient treatment; (ii) Particle-free effluent; (iii) small footprint; and (iv) The potential for remote monitoring and control (Van Dijk and Roncken, 1997).

Correspondence to: Do Tien AnhE-mail: [email protected]


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In practice, the efficiency of MBR for COD and TN removal could reach 90-97% and 44-90%, respectively (Do et al., 2016). Nevertheless, currently, the application of the MBR in developing countries, particularly in Viet Nam, is limited because of two barriers of the MBR which are high energy consumption and fouling of the membrane. Solutions for these two problems have been attracting huge attention from scientists. Thousands of studies have been reported in the past 20 years on this topic. Of which, a few studies on airlift MBR (AL-MBR) have shown very promising results. AL-MBR could reduce energy consumption and avoid the fouling of membrane (Do et al., 2016). The concept of the AL-MBR is to using air to sparge the membrane continuously to control better the build-up of cake-layer which would cause the membrane fouling and higher energy consumption (Futselaar et al., 2007; Prieto et al., 2013; Kijjanapanich et al., 2013). Few studies have shown that energy consumption could be reduced by up to 14-15% if using AL-MBR compared to conventional MBR system (Prieto et al., 2013; Do et al., 2016). Do et al. (2016) reports the AL-MBR could reduce 95±1.9% of COD and 70±3.3% of TN in SHWW at lab scale and concluded that AL-MBR could be a good option for on-site treatment of SHWW in Viet

Nam. However, there have not been reported yet a study on the application of AL-MBR at practice for SHWW treatment.

This study will evaluate the operation of AL-MBR at a slaughterhouse at Nhue - Day River. 2. Materials and Methods

2.1. Activated sludgeSeed activated sludge was collected from

a local wastewater treatment plant (Viet Ha Brewer Corporation, Bac Ninh province, Viet Nam). Prior to use, the sludge was sieved through a 3 mm mesh sieve to remove any debris that could clog the membrane lumen or block the reactor tubing. The TSS and pH of the seed sludge were 1.6±0.1 g/L and 7.24 ± 0.05, respectively.2.2. Slaughterhouse location and SHWW

The slaughterhouse chosen for the study is located at Tri Thuy commune, Phu Xuyen district, Ha Noi. This commune is along the riverside of Day River and has around 30 slaughterhouses. The selected slaughter-house produces approximately 20 m3/day of wastewater. The SHWW was discharged into an on-site septic tank before releasing into a water cannel nearby (Figure 1).

Figure 1. (a) Location of the selected slaughterhouse; (b) A water cannel in front of the slaughterhouse

(a) (b)


The effluent the septic tank was sampled in order to characterize wastewater from the

slaughterhouse. The composition of the SHWW is described in Table 1.

Table 1. The SHWW characteristics in the slaughterhouse selected for this study

Parameters SHWW (effluent of the septic tank)

Viet Nam Discharge Regulation Standard

BOD (mg/L) 640 ± 341 50COD (mg/L) 1060 ± 458 150

NH4+-N(mg/L) 361 ± 106 10TN (mg/L) 451 ± 133 40TP (mg/L) 35±13 6

pH 6.8±0.4 5.5-9TSS (mg/L) 540 ± 141 100

2.3. AL-MBR FabricationThe AL-MBR was designed to treat the

effluent from the current septic tank in the slaughterhouse. AL-MBR was constructed as a 60 m3 biological reactor which includes both aerobic and anoxic functions coupled with two side stream tubular membrane modules. The membranes (length x inside diameter) were 3 m x 5.2 mm polyvinylidene fluoride modules (model code: MO 33G_I5, Berhof, Germany) with mean pore size of 0.03 µm and active filtration area of 4.8 m2 per module. The SHWW was pumped from the septic tank to a 1 m3 intermediate tank by a pump (Model CM100, Pentax, Italy) at a rate of 20 m3/day. The wastewater from the 1 m3 intermediate tank was designed to justify the pH or other parameters

of the wastewater before transported into the biological reactor. The biological reactor consisted of anoxic and aerobic areas. The anoxic and aerobic areas were separated by adjustable metal baffles. The aerobic area in this study was set at 19 m3. An air compressor was providing oxygen to keep DO in the aerobic area around 5 mg/L. The mixed liquor volatile suspended sludge (MLVSS) was kept at 1,500 mg/L. The mixed liquid-sludge from the bioreactor was pumped to the two membrane modules by a pump (Wilo PU 1500E, Korea). The Transmembrane pressure (TMP) was maintained at 2 bar. Cross-flow velocity and air flow rate through the membranes were kept consistently at 0.8 m/s and 0.2 L/min, respectively. The air was provided by a biogas from the slaughterhouse.

Figure 2. Flow scheme of the pilot airlift MBR for SHWW treatment at Tri Thuy, Phu Xuyen

2.4. Analytical MethodsSamples from the influent, mixed liquor in

the aerobic and anoxic reactors, and permeate

samples were taken daily to analyze the COD, NO3--N, NH4+-N, TN, MLSS and MLVSS according to Standard Methods for the Examination of


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Figure 3. Membrane filtration performance

Water and Wastewater by APHA (APHA 2005). Samples for COD, NO3--N, TN and NH4+-N were filtered through a 0.45-µm glass microfibre filter before measurement. COD was determined by the closed reflux, colorimetric method (Method 8000). Total nitrogen (TN) was analyzed by the persulphate digestion method (Method 10071). Nitrate (NO3--N) was measured by the cadmium reduction method (Method 8039). Ammonia (NH4+-N) was measured by the salicylate method (Method 10031). Mixed-liquor suspended solids (MLSS) and mixed-liquor volatile suspended solids (MLVSS) were measured by using the methods 2540D and 2540E, respectively. The permeate flow rate was determined using a digital balance connected to a data logger.

During operation, energy consumption was monitored by using a kWh meter (EMIC Corp., Viet Nam). The energy consumption includes that for the feed pump, the recirculation pump, the internal recycle pump, the vacuum pump and the air blower. The specific energy consumption was estimated based on the flow rate of product water and the energy consumption recorded by the kWh meter.

3. Results and Discussion

3.1. Evaluation of Membrane Filtration Performance

It was observed that the highest permeate flux of the membrane was reached at 80 LMH/bar at the beginning and rapidly decreased to 40 LMH/bar after five days. The cake layer built up on the membrane surface would be the reason for the decrease. After five days, the cake layer would be stable, and the flux was consistently at 40-50 LMH/bar. This value was much higher than the value achieved at the lab scale system which was 18 LMH/bar (Do et al., 2016). The reason could come from differences in operation procedures for pilot and lab scale system. In lab scale system, there was no membrane cleaning procedure applied. However, in the pilot system, the membranes were operated for 20 minutes, then rested for 5 minutes. Of the 5 minutes rested, there were 3 minutes during which the membrane was cleaned with tap water. During a month of operation, there was no serious fouling of the membrane observed.

3.2. Organic matter reduction Wastewater from the slaughterhouse

contains various components which are blood, urine, meat and fat matters. The concentration of organic matters in SHWW is always high.

The concentration of COD in SHWW sampled before the septic tank was 5000-6000 mg/L. The degradation of organic matters in the SHWW was observed after the septic tank. COD in the effluent of the septic tank was analyzed at 1060


Figure 4. COD removal profile

Figure 5. Profile of nitrogen removal

± 458 mg/L. This value of COD was 6-10 times higher than the value permitted in Viet Nam discharged regulation standard. It is shown that a septic tank could help to reduce 90% of organic matters in the SHWW. However, the COD could not reach to regulation standard just by the septic tank. Therefore, the AL-MBR was installed to support the treatment of SHWW.

It was observed that the COD could reach as low as 114±27 mg/L and 86±20 mg/L in the bioreactor and effluent, respectively (Figure 3). COD removal efficiency of the AL-MBR system had achieved 89.1±4%. Biological processes remove 85.5±5.41% and the membrane process contributed an addition of 3.61±1.35%.

3.3. Nitrogen RemovalThe concentration of total nitrogen in SHWW

in Viet Nam is quite high, around 246±65 mg/L. The concentration of total nitrogen in the effluent of the septic tank in the slaughterhouse at Phu Xuyen was much higher. The TN concentration was analyzed at 451±133 mg/L. Most of the nitrogen in the effluent of the septic tank was contributed by NH4+. The concentration of the

NH4+ in the septic effluent was 356±101 mg/L and contributed to 80% of TN. Total nitrogen was removed 82%-94% by biological processes. Total nitrogen was reduced to 63.16±28.5 mg/L in the biological reactor. The concentration of TN in the membrane effluent was detected at 62±28.24 mg/L. The concentration of the TN was even lower in the effluent at 38±4 mg/L after the day 15th of operation.

3.4. Energy consumptionEnergy consumption of the whole AL-MBR

system in the slaughterhouse was measured at

52 kWh/day which is equal to 2.6 kWh/m3. This number is higher than the value reported for energy consumption of AL-MBR at lab scale


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which is 1.45 kWh/m3 (Do et al., 2016). The equipment of the pilot system could be designed and operated higher than the practical demand which is needed to treat 20 m3/day. It should also be noted that in the past 50 years, developments in MBR technology resulted in an energy demand reduction from about 5.0 kWh/m3, needed for the first side-stream MBRs (Buer and Cumin, 2010). The energy requirement of the first tubular side-stream MBR installations was reported to be typically 6.0-8.0 kWh/m3 (Van Dijk and Roncken, 1997), mainly due to energy-intensive cross-flow pumping of the liquid. The value of energy consumption of the pilot AL-MBR is lower than the same scale system for similar wastewater installed and operated in Viet Nam. A 30 m3/day pilot Anaerobic Baffles Bioreactor (ABR) for pig farm wastewater treatment required 2.8 kWh/m3 which is 7% higher than the energy consumption of the pilot AL-MBR (Tua et al., 2015).4. Conclusions

The lack of finance for constructing centralized wastewater treatment plants and conveyance systems is the major reason for

untreated slaughterhouse wastewater discharged into Nhue - Day River. Onsite treatment option is currently considered a good fit for SHWW management to prevent contamination of Nhue - Day River. It is proved that AL-MBR could work well to treat SHWW at pilot scale of 20 m3/day. The system had achieved very promising results of removal of COD and TN. The removal efficiencies of COD and TN were observed at 89.1±4% and 85±8.7%, respectively. The AL-MBR in this study provided consistent permeate flux of 40 LMH/bar at 2 bar. This value is higher than the value recorded at lab scale. The energy consumption at pilot scale was higher than the energy consumption at lab scale due to over operation. It could be concluded that the AL-MBR could work well at both lab scale and pilot scale and could be considered as a good option for upscale for all slaughterhouses along Nhue - Day River or in Viet Nam in future.

Acknowledgement: We really appreciate the financial support for this study from Viet Nam Ministry of Science and Technology. We would like to thank Berghof company, Germany for providing us membrane modules.

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