concept of flood risk (1)
TRANSCRIPT
A Framework for
Flood Risk Management
An Introduction
Dr John Porter
A good place to start if we want to prepare a
strategic framework for managing flood risk is
to define flood risk.
What is flood risk?
There is no one definition of flood risk, but one that
proves very useful for a strategic framework is
RISK = HAZARD x EXPOSURE x VULNERABILITY
RISK = HAZARD x EXPOSURE x VULNERABILITY
Hazard is a potential for harm, loss or damage. Hazard exists wherever land is liable to flooding.Hazard increases with probability and depth of inundation, and with velocity of flow.
RISK = HAZARD x EXPOSURE x VULNERABILITY
Hazard is a potential for harm, loss or damage.
Hazard exists wherever land is liable to flooding.
Hazard increases with probability and depth of inundation, and with velocity of flow.
VISTULA RIVER, POLAND
RISK = HAZARD x EXPOSURE x VULNERABILITY
Exposure
Even where a hazard exists, there is no risk unless there are assets that can be damaged, or there is danger because people live in, work in, or simply transit through the location of flood hazard.
Exposure to flood hazard creates the potential for personal danger or property damage to occur during floods.
BRISBANE, AUSTRALIA
RISK = HAZARD x EXPOSURE x VULNERABILITY
The consequences of flooding – and therefore the risk – also depends on how vulnerable people and their assets are to danger and damage.
Vulnerability can be reduced if people and authorities: take appropriate precautions in advance of flooding, know what to do to limit danger and damage during floods, and receive adequate warning and appropriate assistance during and
after floods.
FUZHOU, CHINA
Defining flood risk as
RISK = HAZARD x EXPOSURE x VULNERABILITY
is very useful because the measures we use in flood
management can be regarded as modifying
(reducing) one of these 3 key elements of risk.
MODIFYING HAZARD
Flood control dams
Detention basins
Levees or dikes
Flood diversion channels
River channel
improvements
Upper watershed
management
MODIFYING EXPOSURE
Zoning of land use
Property acquisition
Planning development
controls
Building codes
Flood-proofing buildings
Building on platforms or
stilts
MODIFYING VULNERABILITY
Flood monitoring and warning
Flood forecasting
Emergency response plans
Community awareness
Community preparedness
Post-flood recovery &
reconstruction
Flood insurance
STRUCTURAL NON-STRUCTURAL
This involves land management in addition to water
management.
In normal circumstances there is a clear division
between water and land. Water is contained within
rivers, lakes and other water bodies.
During floods, the water regime expands to
temporarily inundate land which – most of the time –
can be used for productive purposes.
Therefore, unlike other aspects of water resources
management, flood risk management must embrace
both land use management and water
management.
RISK = HAZARD x EXPOSURE x VULNERABILITY
NOTE ABOUT Exposure to Flood Hazard
NOTE ABOUT Vulnerability
Many have identified that communities are more vulnerable
to flood risk if there is greater poverty, in
communities with low standards of education,
and in societies with poor governance.
RISK = HAZARD x EXPOSURE x VULNERABILITY
INDUS RIVER, PAKISTAN
Vulnerability or susceptibility
This is true. Programs aimed at reducing poverty and
improving education and political governance will reduce
vulnerability and flood risk. However, we can introduce a
new category for these issues and regard them as issues of
Susceptibility rather than Vulnerability. They are different
because they deal with the ills of society as a whole, are
less specific to flood risk as they affect many other aspects
of community life too. And in that sense, although they are
relevant to management of flood risk, they are not proper
undertakings for flood risk management alone.
RISK = HAZARD x EXPOSURE x VULNERABILITY
Comprehensive flood risk management must
therefore consider treatment of all three elements
of flood risk:
HAZARD
EXPOSURE
VULNERABILITY
Consideration of flood risk as the product of
Hazard x Exposure x Vulnerability
only deals with what we do to manage flood risk.
A strategic framework for flood risk management
must also consider how we organize and how we
plan for management of flood risk.
It should also consider the impacts of what we do
on the environment and the community.
Therefore, other important dimensions of a strategic management framework are:
INSTITITIONAL FOUNDATION
PLANNING METHODOLOGY or STRUCTURE
EXOGENOUS IMPACTS (social & environmental)
INSTITUTIONAL FOUNDATION
LEGISLATION
POLICY
ORGANIZATIONAL STRUCTURE
INSTITUTIONAL CAPACITY
FUNDING
EDUCATION & PROFESSIONAL
TRAINING
INSTITUTIONAL FOUNDATION
Typically, responsibilities relevant to flood management are fragmented between multiple government agencies. E f f e c t i v e p a r t n e r s h i p
b e t w e e n a g e n c i e s
d i r e c t e d t o w a r d
c o o r d i n a t e d m a n a g e m e n t
o f f l o o d r i s k i s o n e o f
t h e g r e a t e s t i n s t i t u t i o n a l
c h a l l e n g e s .
WROCLAW, POLAND
PLANNING METHODOLOGY
A well structured method is recommended to capture the
strengths of integrated flood management through:
rigorous technical analysis,
comprehensive assessment of planning options,
appraisals based on the triple bottom line of
sustainable development (economic viability, social equity
and environmental acceptability),
benefit-cost analysis and
stakeholder participation.
CO
NSU
LTATIO
N P
RO
CESS
PRELIMINARY PHASE
Identify & Quantify Flood Risk estimate hydrological risk hydraulic model analysis
map existing flood hazard & land use
TECHNICAL ANALYSIS
Identify Alternative Flood Management Options combinations of structural & non-structural measures evaluate future risk consider how to manage residual risk
Appraisal of Impacts economic analysis tangible & intangible social benefits / disbenefits environment – adverse impacts & opportunities
robustness, resilience to future uncertainty
APPRAISAL PHASE
Recommend Preferred Option refine analysis; examine assumptions
document plan
FLOOD MANAGEMENT PLAN
APPROVAL
IMPLEMENTATION
Define Management Objectives collect data
Understand Planning Context population characteristics property & infrastructure institutional arrangements
planning instruments
PLANNING
METHODOLOGY
PLANNING
METHODOLOGY
PLANNING component of the framework
Structured Planning Methodo Definition of management objectives – start with desired
outcomes, not a proposed solution
o Understanding of the planning context – consider pre-existing plans & local factors
o Identification & quantification of flood risk: technical analyses
o Identification & consideration of alternative ways to manage the flood risk – different options comprising packages of FM measures
o Appraisal of impacts – economic, social & environmental benefits & costs
o Recommendation of a preferred option – refinement of solutions; closer examination of assumptions; documentation
o Stakeholder participation – opportunity for consultation at each step of the process
PLANNING METHODOLOGY
RIVER BASIN MASTER PLANS
SUB-BASIN MASTER PLANS
e.g. - tributaries
- river reaches (over several local govt jurisdictions)
- lake / wetland complexes
URBAN DRAINAGE MASTER PLANS
for internal drainage of cities to mitigate urban flooding
RURAL DRAINAGE MASTER PLANS
to mitigate waterlogging of agricultural land
PROJECT PLANNING
to mitigate specific flooding problems, either at single or joint local government scale
EXOGENOUS
IMPACTS
SAFEGUARDS & SUSTAINABILITY
Social impacts may be positive or negative, and attention must be directed during planning and design to avoid or mitigate adverse impacts, and enhance beneficial outcomes. In particular, impacts on those displaced or resettled, on indigenous groups, on the disabled, aged or infirm, or on gender groups need to be examined and assessed.
Environmental impacts may include unintentional but foreseeable impacts on the physical environment, or on the biosphere.
EXOGENOUS
IMPACTS
Safeguards:
Environmental protection safeguards
Location and storage of hazardous materials
Involuntary resettlement social safeguards
Indigenous peoples’ social safeguards
Assessments of the social implications for
gender (women’s issues)
Assessments of social implications for disabled,
infirm or disadvantaged persons
Locations of strategic community services
INSTITUTIONAL FOUNDATION
PLANNING
FLOOD HAZARD
EXPOSURE
VULNERABILITY
Flood Control Works
Structural planning & design
Asset maintenance:
monitoring condition
rehabilitation /upgrading
funding
Operations:
decision support systems
communications systems
data acquisition networks
integration with WR management
env.management
Catchment Management
Soil conservation
Upland land use management
Land Use Management
flood hazard zoning
land use planning controls
property acquisitions
resettlement
Flood forecasting
hydrological models
hydraulic models & DTMs
flood hazard maps
data acquisition networks
Flood warning & emergency response
communications systems
preparedness exercises
decision support systems
Post-flood recovery
support services: health, counseling
material support: food, shelter
infrastructure repairs
financial assistance & incentives
compensation / flood insurance
Land Use Management
building regulations
River basin master plans
Project proposal planning & appraisal
: risk assessment
: appraisal of alternative options
Planning for emergency response
Planning for post-flood recovery
Urban drainage master plans
Rural drainage master plans
Partnerships: across levels of government Restructuring: enhancing coordination
between different levels of government
Legislation: clarifying mandates Training / awareness / capacity building
ENVIRONMENTAL
SAFEGUARDSSOCIAL
SAFEGUARDS
GENDER
ISSUES
INDIGENOUS
PEOPLES’
SAFEGUARDS
COMMUNITY CONSULTATION
Key requirements to make it effective are
LEGISLATION THAT CLEARLY DELEGATES ROLES AND
RESPONSIBILITIES
A KEY COORDINATION ROLE MANDATED FOR ONE LEAD
AGENCY IN FLOOD RISK MANAGEMENT (or DISASTER
RISK MANAGEMENT) WITH STRONG POWERS TO
OBLIGE PARTICIPATION BY ALL STAKEHOLDERS IN
JOINT PLANNING
BROADER STAKEHOLDER PARTICIPATION THROUGH
COMMUNITY CONSULTATION DURING THE PLANNING
PROCESS
There is the strategic framework for flood risk management.
A sound institutional foundation is of crucial importance.
THANK YOU
THE END
MANILA, PHILIPPINES