CLIMATE CHANGE AND SRI LANKA’S WATER FUTURE

Nishadi Eriyagama (IWMI)¹

Workshop on Vulnerability and Adaptation to Climate Change in the Water Resources Sector, Colombo, Sri Lanka, September 2009

Vladimir Smakhtin (IWMI)¹, Mir Matin (IWMI)¹, Lalith Chandrapala (NDMC)² & Karin Fernando (CEPA)³

With contributions from

1=International Water Management Institute, 2=National Disaster Mitigation Council,3=Center for Poverty Analysis

• Review of the status of climate change research in Sri Lanka– Observed climatic changes– Climate projections– Impacts on water resources– Impacts on agriculture

• IWMI Climate change vulnerability mapping• Sri Lanka Water Resources Audit• Adaptation activities in water resources sector • Research needs

OUTLINE

SOURCES

The review is based on:

• Interviews and e-mail correspondence with 16 officers in government agencies and international bodies

• Over 80 national and global climate change studies

Dry Zone

Wet Zone

Intermediate Zone

Warming trends (0C/year) 1961-2000

OBSERVED CLIMATIC CHANGES

Temperature

Source: Zubair et. al. 2005

Anuradhapura 0.024-0.026

Badulla 0.022-0.024

Rainfall No significant change in Mean

Annual Rainfall Amount

South-West Monsoon (May – Sept): Stable (Yala)

Source: Figure created by N.Eriyagama using IWMI GIS data, 2009

North-East Monsoon (Dec – Feb): reduced & variability increased (Maha)

CLIMATE PROJECTIONS - 1

• General consensus: increasingly warmer in 21st century• IPCC: stronger warming than the global mean in South Asia• Projected magnitude of change: differ from study to study

Temperature

Source Model Scenario Base Year Change at end 21st century

Cruz et. al. 2007

AOGCM A1F1, B1 1961-1990 + 2.93-5.44 0C (South Asia)

Kumar et. al. 2006; Islam and Rehman undated

Regional Climate Model-RCM

A2, B2 1961-1990 + 2-4 0C

(Sri Lanka)

Basnayake et. al 2004

Statistical Downscaling of GCMs

A1F1, B1, A2

1961-1990 + 0.9-3 0C

(Sri Lanka)

Source: Table created by N.Eriyagama, 2009

AOGCM-Atmospheric Ocean General Circulation Model GCM-General Circulation Model IPCC-Inter-Governmental Panel on Climate Change

Lower Mean Annual Rainfall

Mean Annual Rainfall

Higher Mean Annual Rainfall

CLIMATE PROJECTIONS - 2

Rainfall

Increased Variability Increased Floods & Droughts

- Projections for this century confusing and contradictory!

Higher South-West Monsoon R/F

Higher North-East Monsoon R/F

Higher South-West Monson R/F

Lower North-East Monson R/F

Kumar et. al. 2006; Islam and Rehman undated; Basnayake et. al. 2004; Basnayake and Withanage 2004a

Cruz et. al. 2007; De Silva 2006; Basnayake and Withanage 2004b

Lower South-West Monsoon R/F

Lower North-East Monsoon R/F

Ashfaq et. al. 2009; Basnayake et. al. 2004

Source: Flowchart created by N.Eriyagama, 2009

Dry Zone

Wet Zone

Intermediate Zone

Dry Zone

Wet Zone

Intermediate Zone

CLIMATE PROJECTIONS - 3

Spatial Pattern of Rainfall Projections for 2050Projection 1 Projection 2

Ambiguity!

De Silva, 2006

De Silva 2006Basnayake et. al. 2004

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++

+

++

+

+

+

+

+

--

- ---

--

-

+

+

++

+

++

+

+

+

Source: Figures created by N.Eriyagama,2009 using data from Basnayake et.al 2004 & De Silva 2006

IMPACTS ON WATER RESOURCES - 1

• One School of Thought: Gain in Mean Annual Water Availability

• But increased Variability + Inequitable Spatial Distribution

• Brunt of impact on north eastern and eastern dry zone: May become drier!

• Lower water availability in the upper Mahaweli watershed by 2025 (Shantha & Jayasundera, 2005): More power cuts!

Dry Zone

Wet Zone

Intermediate Zone

Source: Figure created by N. Eriyagama, 2009

IMPACTS ON WATER RESOURCES - 2

• Average wet season reference evapotranspiration (ET0) may increase by 1-2% by 2050

• Average Maximum Annual Potential Soil Moisture Deficit may increase by 4-11% by 2050

• Increase in Maximum Annual Potential Soil Moisture Deficit in the Dry and intermediate zones by 2050: More irrigation!

• Worst affected: Batticaloa • However, Hambantota: more rainfall /

lower irrigation requirement

Dry Zone

Wet Zone

Intermediate Zone

Batticaloa

Hambantota

Source: Figure created by N. Eriyagama, 2009

IMPACTS ON AGRICULTURE

Paddy Tea Coconut

Irrigation Requirement:

13-23% increase in Maha by 2050 (De Silva 2006)

Yield:

100 mm monthly R/F reduction: 30-80 kg reduction in ‘made’ tea/ha (Wijeratne et. al., 2007)

Heavy rains: erode top soil and wash away fertilizers, reduce yield (Wijeratne, 1992)

Economy:

Low rainfall: Losses in the range $32 - $73 million a year (lower yield)

High rainfall: Gains in the range $42 - $87 million a year (higher yield) (Fernando et. al 2007)

Impacts on Agriculture due to Altered Water Resources

Source: Table compiled by N.Eriyagama, 2009 using data from Fernando et.al 2007, Wijeratne et.al 2007, De Silva 2006 & Wijeratne, 1992

CLIMATE CHANGE VULNERABILITY MAPPING -1

Climate Change Vulnerability Index

Anuradhapura

Nuwara-Eliya

Ratnapura

Sensitivity Index

Exposure Index

Adaptive Capacity Index

Source: Figures created by N. Eriyagama, 2009 using data mainly from the Department of Census and Statistics-Sri Lanka

CLIMATE CHANGE VULNERABILITY MAPPING -2

Exposure Index based on: Frequency of exposure to historical droughts, floods, cyclones

Sensitivity Index based on: Population density, % employed in agriculture, irrigation water availability, agricultural diversity (crops diversity, livestock farming, fishing)

Adaptive Capacity Index based on: education level, poverty incidence, level of infrastructure development

0 – lowest vulnerability 100 – highest vulnerabilitySource: Figures created by N. Eriyagama, 2009 using data mainly from the Department of Census and Statistics-Sri Lanka

CLIMATE CHANGE VULNERABILITY MAPPING -3

Anuradhapura

Nuwara-Eliya

Ratnapura

Highly vulnerable areas are:

• Typical farming areas

• Have low socioeconomic and infrastructural assets (low adaptive capacity)

• Show high levels of exposure to historical climate extremes

• Rely heavily on water availability for agriculture

Source: Figures created by N. Eriyagama, 2009 using data mainly from the Department of Census and Statistics-Sri Lanka

SRI LANKA WATER RESOURCES AUDIT - 1

• A web based tool to assess:

– Water availability– Water demand– Water quality– Water governance structure– Water related disasters– Climate change impacts

• Data depository with a host of data at one place• A tool for accessing and analyzing hydro/meteorological data• Work in progress, but basic platform is ready• Already contains data on rainfall time series, water demand etc. • Requires participation of national agencies to incorporate more data

and information Source: http://idistest.iwmi.org:8080/slwa/

SRI LANKA WATER RESOURCES AUDIT - 2

Physical and Admin Settings Hydro/meteo Data Water Demand

Water Infrastructure Natural DisastersSource: http://idistest.iwmi.org:8080/slwa/

ADAPTATION ACTIVITIES

• Water resources adaptation options under consideration:– Rainwater harvesting and storage– Renovating existing tanks– Development of sustainable groundwater– Use of micro-irrigation technologies– Waste water reuse– Increase efficiency of water use and modify allocation practices– Greater shift towards alternative energy from hydropower

• Climate tools developed:– Predicting seasonal water availability within the Mahaweli scheme– Predicting annual national coconut production based on climate

• Climate Change Action Plan for Sea Level Rise - Coast Conservation Department (CCD)

RESEARCH PRIORITIES

• Detailed and reliable climate scenarios based on a Regional Climate Model (RCM)

• Comprehensive national study on river basin or district scale on vulnerability of water resources to climate change covering:– Both surface and ground water– Water quantity and quality

• A National Water Resources Audit

• Central Agency to cater to the need for data sharing and corporation: Water Resources Board?

THANK YOU !

ACKNOWLEDGEMENTS: • Dr. B. V. R. Punyawardane, Department of Agriculture• Ms. Dharshanie De Silva, World Bank• Ms. Chandanie Panditharatne, Ministry of Environment and Natural Resources• Mr. Sarath Premalal, Department of Meteorology• Mr. Bandula Wickramarachchi, Coast Conservation Department (CCD)• Ms. Neranjana Gunatilleke, Centre for Poverty Analysis (CEPA)• Mr. Amila Balasuriya, Centre for Poverty Analysis (CEPA)• Mr. N. Wickramaratne, Mahaweli Authority• Mr. H. M. Jayatillake, Irrigation Department• Mr. K. A. U. S., Imbulana, Ministry of Irrigation• Mr. L. Manawadu, University of Colombo• Dr. W. M. W. Weerakoon, Rice Research and Development Institute (RRDI)• Dr. G. G. A. Godaliyadda, Irrigation Department• Dr. A. W. Jayawardena, Public Works Research Institute, Japan • Mr. Gerard Fernando, National Water Supply and Drainage Board• Mr. Harsha Sooriyarachchi, Water Resources Board• Staff of Sri Lanka Association for the advancement of Science (SLASS)

REFERENCES: IWMI Research Report -135, Forthcoming