drought and flood management presentation a k lohanii nih
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DROUGHT AND FLOOD MANAGEMENT SCENARIO
IN INDIA
A.K. LOHANI
SCIENTISTEmail: lohani@nih.ernet.in
aklnih@gmail.com
akl_nih@yahoo.co.in
NATIONAL INSTITUTE OF HYDROLOGYROORKEE-247667
(UTTARAKHAND)
INDIA
• India is the most natural disaster prone area in the world.
• About 40 mha area of the country is flood prone and on average floods affect an area of about 7.5 mha
• About 153 mha are of the country is drought prone
• Every year country experiences these water extremes (floods and droughts) either on small or larger scale
FLOOD AND DROUGHTS
• The Ganga and Brahamputra are the chronic flood prone river basins
• The magnitude of precipitation over these basins is very high and more than three-quarters occurs during summer monsoon (June-Sept.).
• Natural hazards such as floods, droughts, earthquakes and cyclones affect an estimated 25 million people every year
• India accounts for nearly one-fifth of global death due to floods
Unlike other natural disasters, drought Unlike other natural disasters, drought does not have a clearly defined beginning does not have a clearly defined beginning
and end. As a result, our reaction to and end. As a result, our reaction to drought traditionally has not been timely.drought traditionally has not been timely.
DROUGHT
DEFINITIONS OF DROUGHT
• Meteorological droughtMeteorological drought
• Hydrological droughtHydrological drought
• Agricultural droughtAgricultural drought
DROUGHT PRONE AREASDROUGHT PRONE AREAS
Sl. No.
Meteorological sub-division Frequency of deficient rainfall
( 75% of Normal or less)
1 Assam Very rare, once in 15 years
2 West Bengal, Madhya Pradesh, Konkan, Bihar and Orissa
Once in 5 years
3 South Interior Karnataka, Eastern Uttar Pradesh and Vidarbha
Once in 4 years
4 Gujarat, East Rajasthan, Western Uttar Pradesh
Once in 3 years
5 Tamil Nadu, Jammu & Kashmir and Telangana
Once in 2.5 years
6 West Rajasthan Once in 2 years
OBSTACLES TO EFFECTIVE OBSTACLES TO EFFECTIVE DROUGHT MANAGEMENT PLANNINGDROUGHT MANAGEMENT PLANNING
• Clarity About Beginning and End of Drought
• Randomness Associated with Drought
• Drought Phenomenon
• Economics of Droughts
• Social And Political Considerations
DROUGHT MANAGEMENT • Water Supply Conservation & Management
Measures • Water Demand Reduction and Management
Measures – Active demand reduction – Reactive demand reduction
• Water Conservation• Hydrological Preparedness for Impending Drought • Impact Minimisation • Efforts to Combat Desertification
DROUGHT MANAGEMENT
• Rehabilitation of Mined Aquifers • Research in Agro-meteorology • Remote Sensing and GIS Application for
Drought Management • Decision Support System in Drought
Management • Peoples Participation in Drought
Management
Contd...
DROUGHT MANAGEMENT Water Supply Conservation & Management Measures • Development of new water supply• Conjunctive Use• Agronomic, Soil& Water Conservation Measures• Watershed management• Reservoir & Tanks• Inter basin water transfer• supply of treated domestic, Industrial and municipal
waste water• Artificial recharge• Rainwater harvesting
Contd...
DROUGHT MANAGEMENT Water Demand Reduction and Management Measures
– Active demand reduction – Reactive demand reduction
Active demand reductionActive demand reduction• Provision of legal restrictions• establishment of thresholds for short term
reduction to various users• Land use planning• Water pricing
– High beyond a prescribed limit– Incentives for using small amount of water
Contd...
DROUGHT MANAGEMENT
Reactive demand reductionReactive demand reduction
• Use of Recycling System
• Selection of Cropping Pattern
• Reduction in Urban water supply
• Water budgeting in Industries
Contd...
DROUGHT MANAGEMENT Water ConservationWater Conservation• Control of evaporation• Rain water Harvesting• Provision of water cisterns• Water conservation campaign
Contd...
DROUGHT MANAGEMENT
Hydrological Preparedness for Impending Hydrological Preparedness for Impending
Drought Drought
• Information on hydrological data
• System of hydrological monitoring to solve
drought problems
• Variability in the total amount of rainfall
• Variability in the total hydrologic process
Contd...
DROUGHT MANAGEMENT Impact MinimisationImpact Minimisation • Anticipating actions and decisions
before a drought actually occurs• Variation of soil moisture, fluctuation of
groundwater and streamflow• Prediction of soil moisture using
simulation model
Contd...
DROUGHT MANAGEMENT Efforts to Combat DesertificationEfforts to Combat Desertification• More than 1/3 of the total land area of globe is
prone to the hazards of desertification• In India arid zone covers about 12% of
country’s geographical area. – Rajasthan- 62%– Gujarat - 19%– Punjab & Haryana - 9%– Andhra Pradesh & Karnataka - 10%
• Special program launched since 1970-71
Contd...
DROUGHT MANAGEMENT
Rehabilitation of Mined Aquifers
• Control of GW withdrawal • Augmenting GW recharge
Contd...
DROUGHT MANAGEMENT
Research in Agro-meteorology• Need to give warning to farmers much in
advance regarding• seasonal variation in rainfall• rainfall distribution• climatic conditions & its variability
Contd...
DROUGHT MANAGEMENT
Remote Sensing and GIS Application for Drought Management
• RS & GIS based Drought Information System
• Development of Drought Indices
Contd...
DROUGHT MANAGEMENT
Decision Support System in Drought Management
• Using a DSS, a person responsible for the actual project is able to make rational use of the system without an in-depth knowledge of modelling techniques
Contd...
DROUGHT MANAGEMENT
Decision Support System in Drought Management
• used for timely recognition of onset of drought.• Identify area vulnerable to drought (in time domain).• Updated information on availability of water (surface &
Ground water) in space and time. • Suggest the actions required by decision makers
against the given scenario of drought condition.
Contd...
DROUGHT MANAGEMENT
Peoples Participation in Drought Management
• Involve common people• Provide incentives• Role of NGO’s
Contd...
FLOODS IN INDIA
• Most frequent and devastating natural disaster• Frequent with varying magnitude• Hydro-meteorological conditions
– Monsoon during four months
• Flood risk to unprotected as well as protected areas
• Flood Prone Area - 40 m.ha(as per Rashtriya Barh Ayog)
- 45.64mha (as reported by the States to the
working Group for tenth plan)
FLOOD PRONE REGIONS IN INDIA
• Brahmaputra River Region
• Ganga River Region
• North West River Region
• Central India and Deccan Region
FIVE MAJOR FLOOD PRONE STATES IN INDIA
(As reported in RBA report)
• ASSAM
• BIHAR
• WEST BENGAL
• UTTAR PRADESH
• ORISSA
States Mostly Affected By Floods
13.910.4
31.5
16.36
42.6
29.49
8.7
0.64
14
4.8
73.36
16.02
26.5
22.66
0
10
20
30
40
50
60
70
80
AndhraPradesh
Assam Bihar Kerala Orissa UttarPradesh
WestBengal
Flood Prone Area as per RBA
Area Protected upto March2002
Lak
h
ha
DEFINITIONS OF FLOOD • Defining a flood is a difficult task
• Chow (1956) defined flood as, “a flood is a relatively high flow which overtakes the natural channel provided for the runoff”.
• Rostvedt and others (1968): Included artificial channels
• WMO(1978) : rise in the water level
• Dhar & Nandargi(1998): Flood when water level crosses danger level
CAUSES AND CONDITION OF CAUSES AND CONDITION OF FLOODINGFLOODING IN INDIAIN INDIA
• Very heavy local rainfall• heavy rainfall synchronizing with river spill;• cyclones; • Spilling of water from streams due to low carrying capacity • back water effect in tributaries when the main river carries
heavy discharge • landslides blocking in stream courses and ice jams resulting in
the back water overflowing river banks;• flooding in coastal area due to high tides; and inadequate
drainage/ drainage congestion to carry away surface water with the desired quickness etc.
• flooding due to the failure of flood control structures.
TYPES OF FLOOD
• Flash floods
• Single event floods
• Multiple event flooding
• Seasonal floods
• Dam break floods • Floods due to drainage
congestion
FLOOD PROBLEMS IN INDIA
• about 41 million hectares, or nearly one eighth is considered flood prone
• about 8.6 M ha of land area is annually affected
• average annual damages of the order of Rs.2,500 Crores
CHRONIC FLOOD PRONE BASINS: a) GANGA b) BRAHMAPUTRA
FLOODING IN HIMALAYAN RIVERS DUE TOHIGH DISCHARGE DURING MONSOON MONTHS
DEPOSITION OF SEDIMENTS CAUSE: a) RISE IN RIVER BED b) REDUCES CHANNEL CARRYING CAPACITY
FLOODS ASSOCIATED WITH CYCLONES AS INGUJARAT, ORISSA AND A.P.
AREA SUSCEPTIBLE TO FLOOD DAMAGE: in 1960 ~ 19 M ha in RECENT TIMES ~ 59 M ha
POSSIBLE REASONS a) URBAN & INDUSTRIAL EXPANSION b) DEFORESTATION c) OVEREXPLOITATION & MISUSE OF CATCHMENTS CAUSING LOW WATER RETENTION AND INCREASED RUNOFF d) ENCROACHMENT IN FLOOD PLAINS
PAREECHU LANDSLIDE DAM
A major landslide in Tibetan Himalaya on the banks of Pareechu river created an artificial dam which build up an artificial lake of approx. 200 hectares & 60 m deep.
(Francis, S. et al, 2004, GIS Development)
More than 900 mm rainfall in a Day in Mumbai
MAGNITUDE OF FLOOD DAMAGES
Figure 1: Area affected (Thousnad Ha) due to floods during year 1953-2000
0
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4000
6000
8000
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12000
14000
16000
18000
20000
Year
MAGNITUDE OF FLOOD DAMAGES
Figure 2: Population affected Tthousand) due to floods during year 1953-2000
0
10000
20000
30000
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80000
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MAGNITUDE OF FLOOD DAMAGES
Figure 3 : Human lives lost due to floods during year 1953-2000
0
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12000
Year
MAGNITUDE OF FLOOD DAMAGES
Figure 4:Total monetary damage (Rs. Cr.) due to floods during year 1953-2000
0
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4000
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7000
Year
CAUSES OF FLOOD IN THE
BRAHMAPUTRA VALLEY 1. PHYSIOGRAPHIC
CONDITION OF THE VALLEY
Width of the Brahmaputra river valley is only 80 to 90 km.
The river itself covers about 6 to 10 km in most places and in places even up to 18 km.
This condition lends it favourable for occurrence of frequent floods.
CAUSES OF FLOOD IN THE BRAHMAPUTRA VALLEY- contd.
2. Hydro-meteorological Conditions RAINFALL Heavy rainfall experienced every year due to south
west monsoon.
Annual rainfall ranges from 2480 mm to 6350 mm .
Rainfall is largely concentrated during 4 to 5 monsoon months is responsible for the floods in the valley.
The highest hourly rainfall recorded at Saralpara is 97.5 mm on 27.08.1977
3. Earthquakes and Landslides
The Brahmaputra basin lies in an area of acute seismic activity. (Zone – V).
The earthquakes of 1897 and 1950 are the most severe earthquakes.
3 m rise in the general low water level was observed at Dibrugarh.
The rise of bed level of Brahmaputra after the 1950 earthquake resulted in the development of a number of new spill channels on both banks
CAUSES OF FLOOD IN THE BRAHMAPUTRA VALLEY- contd.
CAUSES OF FLOOD IN THE BRAHMAPUTRA VALLEY- contd
5. ENCROACHMENT OF RIVERINE AREAS
Upto the 19th century, population was comparatively thin and human habitation was away from the river banks.
The population increased manifold during the 20th century resulting in encroachment of riverine areas.
Such encroachment decreased the waterway of river leading to spilling of banks and causing floods.
FLOOD MANAGEMENT AND CONTROL
• Structural Measures
• Non-structural Measures
FLOOD MANAGEMENT AND CONTROL
• Structural Measures– Reservoirs for the temporary
storage of flood waters– Embankments (dikes or levees) and
flood walls – The improvement of river channels
to enlarge their discharge carrying capacity
– Bypass and diversion channels to carry some of the excess flood water
NON‑STRUCTURAL MEASURES
Flood Forecasting
• Flood Magnitude and Lead Time
• Conventional Regression Method
• Rainfall-Runoff Models
• ANN
• Fuzzy Logic
Dam Break Flood Wave Simulation
• Predict Flood Characteristics: Peak Stage, Discharge, volume, flood wave, Travel Time
• Analysis is required for planning purpose
NON‑STRUCTURAL MEASURES...
Flood Inundation Mapping
– Remote Sensing & GIS Techniques• Reasonable good estimate• Timely information• Covers large area• Useful in planning purpose
NON‑STRUCTURAL MEASURES...
Flood plain Zoning
These provide information about:the areas to be inundated by floodsreturn periods of the floods depth of flooding over the flood
affected areas andthe risk associated with the flooding
NON‑STRUCTURAL MEASURES...
Flood Insurance– Most effective method to regulate the land uses
in the flood plain. – Insurance premium is charged depending upon
the nature nature and location of establishment– In India Scheme is not yet implemented
NON‑STRUCTURAL MEASURES...
DSS FOR REAL TIME FLOOD FORECASTINGDSS FOR REAL TIME FLOOD FORECASTING
•Data Aqusition System
•Input Processors
•Knowledge based real time flood forecasting system
• Output Processors
• Information Dissemination
NON‑STRUCTURAL MEASURES...
CONCLUDING REMARKS
• DROUGHT MANAGEMENT• Drought have Low priority• Drought Planning & Management schemes
– after persistence drought
• After normal rainfall rapid – decrease in drought planning schemes
• DSS at basin scale – outputs at Administrative scales
• People participation• Publication campaign
– Electronic & Print Media
CONCLUDING REMARKS
• FLOOD MANAGEMENT• Study of flood phenomenon• Study of Sediment Phenomenon• A combined approach considering
structural and non-structural measures• Use of GIS & RS• Need to develop a DSS• Need to improve cooperation &
coordination between different organisations
THANK YOU
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