Flood Evaluation, Livelihood Implications

and Adaptation Measures in Sri Lanka

Giriraj Amarnath, Yoshiaki Inada, Surajit Ghosh, Niranga Alahacoon, Umer Yakob,

Harada Kota, Ryosuke Inoue, Brindha Karthikeyan, Joseph Price, Mohammed Aheeyar,

Sanjiv De Silva, Herath Manthrithilake, Vladimir Smakhtin

International Water Management Institute (IWMI), Sri Lanka

National Workshop on “Use of Space Based Information for Disaster

Management”

Colombo, Sri Lanka, 17 November, 2014

• The frequency of flood disasters in Sri Lanka is rising. Hypotheses for this phenomenon

are numerous:

increased climatic variability, the expansion of human settlement in flood

plains, and land cover and land use changes together are believed to be

increasing human exposure and sensitivity to flood impacts.

• The persistence of loss in face of increased knowledge about the dynamics, drivers,

and outcomes of hazards may well signal a significant lack of sustainability in social-

environmental relations, as well as a need to reconsider the underlying principles of

flood management.

Background

Need for a better knowledge on the scale of flooding at various scales thatincludes flood extent, flood depth to assess agriculture loss and populationexposure and integration of science-based inputs in flood management todevelop the best possible flood-risk solutions.

Problem and solutionsIssues

Scale of Challenge

Evidence on current risks and opportunities• Who & what is affected• Scale of consequences

Adaptation context

Current adaptation

actions

Barriers of adaptation

Case for intervention

• Adaptive capacity• Key relevant policies• Assessment of actions across

decision makers• Lack of solutions across institutions

Published evidence/new analysis/stakeholders inputs

• Barriers of action:• Policy• Behavioral• Governance

• Adaptive management solutions• Recommendations

1

2

3

Published evidence/new analysis/stakeholders inputs

Three Stages of approach for appropriate adaptation

Research framework

Flood Evaluation, Livelihood

Implications and Adaptation Measures

Flood Risk Assessment

Developing Flood

scenarios for Risk

Reduction

Flood Loss Estimates

Institutional Analysis and Adaptation Strategies

Flood frequency analysis, Inundation modeling at basin scale and provide scenarios for flood protection measures

Blending RS data and socioeconomic and land use to spatially quantify agriculture impact from flooding

Integration of Sciences, local perception to understand Livelihood changes, managing flood risks

Mapping Historical to Current Flood Extent using MODIS and SAR Satellite images

Remote sensing-based flood-risk mapping: Sri Lanka

• Remote sensing approach was employed to estimate flood frequency and extent.

• Agricultural impact from floods is being studied.

• Potential of flood-risk mapping and piloting agricultural insurance products using EO data and

models are the future areas of research in Sri Lanka

Flood Inundation Extent using ALOS PALSAR data

Extent of flooding during the

years 2006–2011 derived from

ALOS PALSAR data (left) and

cropland extent (right) in Sri

Lanka

• Fine-scale flood-risk products mapped using

satellite datasets from 2000 to 2011.

• Province-wise flood statistics and agricultural

impacts are being analyzed.

• Knowledge generated here can be used by the

Disaster Management Centre and the Irrigation

Department for mitigation, preparedness and

index-based crop insurance

Eastern Province (Trincomalee)

Agricultural flooding in Polonnaruwa

Flood Inundation Modeling and Flood Protection measures

Basin features– Location- Ampara and Batticaloa Districts

Eastern Province

– Catchment area - 1,280 km2

– Three tributaries: Rabukkan Oya, GallodaiAru and Maha Oya

– Uni-modeal Rainfall distribution: main rainy season NE monsoon

– Jan. to Mar. (SW monsoon season)- severe shortage of water resulting in cultivation restrictions

– NE monsoon season-flood problem resulting in loss of life and agricultural production

– Exiting structure (e.g.Rugam Tank) is not sufficient to reduce flood water

– Need for multi-purpose river basin development

with counter measure, the flood risk in the

downstream part (Paddy area) is drastically

reduced

Without counter measures (with existing

Tank)-the downstream are highly

impacted from flooding

Flood Inundation Modeling and Flood Protection measures

Flood Risk Maps

Densely populated areas near the downstream of basin are under the risk of flooding

Major land use type that fallen under the flood risk is paddy area (RED COLOR)- and the most productive areas to be lost!

Recommendation and Messages

• Integrated flood risk management

that reduces flood risk while

increasing its positive impact is

needed

– Socio-economic aspects

• Building multi-objective reservoir that

reduces flood impact during wet

season and used stored water for

irrigation purpose during dry season

• Proper Dam operation and application

of basin scale forecasting system

– Ecosystem Management aspect

• Re-establishing wetlands in the

downstream of the basin area

• Re-forestation in the upstream areas

www.iwmi.org

Water for a food-secure world

Measure an event intensity

Agriculture Loss Estimates from Flooding - RADAR

Event

Event Intensity

Percentage Loss

Damage

Flood depth, period Precipitation

Model Base or Remote Sensing

Translate from intensity to loss

Knowledge Base

Calculate the damage from component values

Data Base

www.iwmi.org

Water for a food-secure world

Basic concept of RADAR

Value densityPercentage

LossAffected area Damage

X (Rs/ha)

Flood

Damage is function of three variables

Z (%)

Y (ha)

Damage (Rs)

www.iwmi.org

Water for a food-secure world

Yield

Price

Value Density

Percentage Loss

Damage by Component

Paddy

Precipitation

Residence Area

Farm Asset Value per Farmer

Farm Asset

Number of houses

Farmer Ratio

Number

Price

Livestock

Habitat Area

Flood event

CropCalendar

Exposed Ratio

Damage by District

Total Damage

Flood depth, period

Input (constant)

Input (after flood)

Output

Affected Area

Damage Calculation Process

www.iwmi.org

Water for a food-secure world

Affected Area

Paddy

Inundated Area

Water Body

Land Use Map (Survey Dpt.) Flood Map ( Feb 2011 Flood)

Affected area by land use will

be obtained

www.iwmi.org

Water for a food-secure world

Just input affected area from GIS, then

You can immediately estimate the damage

Data Synthesis

2. Input after Flood

(Affected area)

3. Run the program and damage

will be automatically calculated

1. Input before Flood

www.iwmi.org

Water for a food-secure world

Results (in Batticaloa)

Paddy

Livestock

Farm asset

676 mil.Rs

257 mil.Rs

762 mil.Rs

2.34 billion Rs.

1.70 billion Rs.

RADAR Estimate Reported Estimate*

*source: District secretariat – Batticaloa and Disaster Management Centre

Estimated DamageComparison with

Direct measurement

Integration of science and policy

• Science-based information (flood mapping, flood risk modeling and

RADAR) can be shared among institutions

• Streamlined into national institutional framework to improve capacity

for better decision-making (requires coordination mechanisms)

• Outcomes:• Guide suitable planning and investments

• Preparedness

• Early warning

• Emergency response

• Tangible products which demonstrate why one avenue of public

spending may be appropriate• Justify and rationalise public policy (Poussin et al, 2012)

‘Living with floods’

• Floods inevitable - softer adaptation strategies can be

more productive than heavy structural measures

• Concept – focus on political-economic, cultural and

historical dimensions of disaster• Above factors can determine risk perception (subjective)

• Flood accepted as norm of land-use, rather than ‘hazard’

• Livelihood strategies - diversification & distribute/plan

farming activities accordingly

• Local perspectives can be incorporated into policy to

address needs & flexible solutions

Application to Batticaloa District

• Concept is applicable to Batticaloa – susceptible to flood

disasters and strong dependence on agriculture (paddy)

• Fieldwork currently being carried out to understand

institutional structure and identify livelihood adaptation

strategies:• Questionnaires, surveys & interviews

• Two villages of different inundation levels

Source: http://sangam.org/2011/02/images/FloodsBatticaloaJan20112.jpg.

Case study expectations

• Social scientific data:• Qualitatively evaluate risks posed by floods - understand and improve

methods of coping on local-scale

• Highlight coordination mechanisms and identify gaps

• Consider best practices in flood management

• Reveal opportunities for institutionalizing scientific tools developed by IWMI