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Flood Evaluation, Livelihood Implications and Adaptation Measures in Sri Lanka


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Presented by Giriraj Amarnath at the National Workshop on “Use of Space Based Information for Disaster Management” Colombo, Sri Lanka, November 17, 2014

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Flood Evaluation, Livelihood Implications and Adaptation Measures in Sri Lanka

  1. 1. 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
  2. 2. • 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 that includes flood extent, flood depth to assess agriculture loss and population exposure and integration of science-based inputs in flood management to develop the best possible flood-risk solutions.
  3. 3. Problem and solutions Issues Scale of Challenge Evidence on current risks and opportunities • Who & what is affected • Scale of consequences Adaptation context Current adaptation actions • Adaptive capacity • Key relevant policies • Assessment of actions across decision makers • Lack of solutions across institutions Barriers of adaptation Case for intervention 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
  4. 4. Research framework Flood Risk Assessment Flood Evaluation, Livelihood Implications and Adaptation Measures Developing Flood scenarios for Risk Reduction Flood Loss Estimates Integration of Sciences, local perception to understand Livelihood changes, managing flood risks 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 Mapping Historical to Current Flood Extent using MODIS and SAR Satellite images
  5. 5. 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
  6. 6. Flood Inundation Extent using ALOS PALSAR data
  7. 7. 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
  8. 8. 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, Gallodai Aru 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
  9. 9. Flood Inundation Modeling and Flood Protection measures 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
  10. 10. 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!
  11. 11. 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
  12. 12. Agriculture Loss Estimates from Flooding - RADAR Water for a food-secure world Measure an event intensity Event Event Intensity Percentage Loss Damage Flood depth, period Precipitation Model Base or Remote Sensing Knowledge Base Translate from intensity to loss Data Base Calculate the damage from component values
  13. 13. Damage is function of three variables Affected area Damage Z (%) Water for a food-secure world Basic concept of RADAR Value density Percentage Loss X (Rs/ha) Flood Y (ha) Damage (Rs)
  14. 14. Damage Calculation Process Yield Price Value Density Water for a food-secure world Percentage Loss Damage by Component Paddy Precipitation Farm Asset Residence Area Farm Asset Value per Farmer Farmer Ratio Number of houses Livestock Price Number Habitat Area Flood event Crop Calendar Exposed Ratio Damage by District Total Damage Flood depth, period Input (constant) Input (after flood) Output Affected Area
  15. 15. Land Use Map (Survey Dpt.) Flood Map ( Feb 2011 Flood) Water for a food-secure world Affected Area Paddy Inundated Area Water Body Affected area by land use will be obtained
  16. 16. 1. Input before Flood Just input affected area from GIS, then You can immediately estimate the damage Water for a food-secure world Data Synthesis 2. Input after Flood (Affected area) 3. Run the program and damage will be automatically calculated
  17. 17. Estimated Damage Comparison with Direct measurement Water for a food-secure world Results (in Batticaloa) Paddy Livestock Farm asset 676 mil.Rs 762 mil.Rs 257 mil.Rs 2.34 billion Rs. 1.70 billion Rs. RADAR Estimate Reported Estimate* *source: District secretariat – Batticaloa and Disaster Management Centre
  18. 18. 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)
  19. 19. ‘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
  20. 20. 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:
  21. 21. 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