Eng. S. Sumanaweera Assistant General Manager Research & Development National Water Supply & Drainage Board 20th August 2009

NWSDB 2009 1 •The most challenggging environmental issue of the 21st Century.

¾ Emissions resulting from human activity

¾IPCC reports global mean surface temperature increase by 0.6 deg.C in last 100 years

¾Expected global mean sea level rise of 0.6 m by 2100.

¾Affect hydrological cycle‐ increased intensity and frequency of precipitation

¾ Floods and Droughts

NWSDB 2009 2/22 •Access to safe dkdrinking water 77.6% • Access to piped water 33.6% Kalatuwawa •Hand pump and tube wells coverage 10% •Number of Water supply schemes 308 •Staff per 1000 connections 7.6 •Non Revenue water 32.1% •Total annual water production 424 MCM Western province water supply

•Fed by Ambatale, Labugama, Kalatuwawa and Kaluganga •Western province supply is 63.6% of All island water production •This abstraction is about 1.7% of the Kelani Kalu, Maha, Attanagalu Runoff toNWSDB the 2009 sea 3/22 Detail of 424 MCM piped drinking water prodtiduction on PPirovince bbiasis in 2007‐ VlValues in % 3 414.1 9.7 3.9 0.4 2.2 10.1 Southern 3.1 Central Western Uva North Central Nothern Sabaragamuwa North Western Eastern

63.6 NWSDB 2009 4/22 Annual Discharge to Sea (MCM)

Annual discharge Zone River basin to the sea (MCM) Mahaweli 1Mahaweli Zone Mahaweli 11016 Zone

South East dry South East Dry 2 zone Walawe 2200 11,016 Zone 428 Menik Ganaga 484 19,368 North West 427 Dry Zone Wila oya 218 4,151 Heda oya 394 WtWestern WtWet North West dry 3,901 Zone 3 zone 1485 1129 198 ¾The Total annual production Modaragama aru 169 of piped drinking water (424 Malwatu oya 566 112 MCM) is 1.1% of the total Kanagarayan aru 242 Annual Runoff where irrigation 4Western wet zone Nilwala 1379 Gin 2178 use is about 95% Bentota 1247 ¾ Kalu 8140 The projected demand for Kelani 5579 2012 will be about 525 MCM Attanagalu oya 845 about 14%1.4% of annual runoff TOTAL 38,436 NWSDB 2009 5/22 Manchanayake, P. & Bandara, C.M.M., 1999 Drinking Water Demand Projection

500 480 Other increasing 460 demands 440

420

400 ¾Energy MCM 380 ¾Irrigation 360 ¾Losses ‐evaporation 340

320

300 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year Demands shall be met by supply

RAIN !

NWSDB 2009 6/22 Trends of Rainfall in over (Last century) (Last 50 years) the Last Century

•100 yr – Colombo up by 3.15 mm/yr‐ N’Eliya & Kandy down by 4.87 & 2.88 mm/yr

•Last 50 years – decreasing trend in 13/15 stations

NWSDB 2009 7/22 According to UK Hadley Centre for Climate Prediction and Research model, HadCM3 Scenarios A2 and B2 of Intergovernmental panel of Climate Change (IPCC) Special Emission Scenario report for the 2050s :

¾ Maximum annual potential soil moisture deficit is predicted to increase significantly in the dry zone

¾ In 2050 there will be a increase in the rainfall during the South West monsoon btbut the NthNorth EtEast monsoon rains decrease

¾ 10% decrease of annual runoff with respect to base line 1961‐1990 in Dry Zone.

¾ In wet zone the annual runoff is expected to increase by 40% to 100% causing land slides and floods

Silva, C.S. (2009)

NWSDB 2009 8/22 http://www.nahrim.gov.my/wkh/PDF%20WKH/ToT/1.%20Presentation/Day%201/ accessedNWSDB 9th August 2009 2009 9/22 Base raifllinfall

NWSDB 2009 10/22 http://www.nahrim.gov.my/wkh/PDF%20WKH/ToT/1.%20Presentation/Day%201/ accessed 9th August 2009 ¾ AlAnnual raiifllnfall is rediducing diduring past century in the upper watershed area by 39.12%

¾This reducing trend will proceed at 16.6 % reduction during next 21 years

Shantha, W.A and Jayasundara, J.S.M.B. www.stabilisation2005.com/posters/ Shantha_ WWA.ppfdf accessed 09th August 2009

NWSDB 2009 11/22 Jayawardena Wijesekera, S., Silva, C.S. Shantha, W.A. ,et.al. Chandrapala 2009 and 2005 ,1996 Jayasundara, J.S.M.B. (2005) Sri Lanka Sri Lanka Sri Lanka Mahaweli zone rainfall rainfall rainfall runoff Last 100 yrs Wet zone 40‐100% Rainfall reduction rainfall increase increase of Wet reducing N’Eliya 4.87 upto 2050 zone annual during past 100 Kandy 2.88 & runoff in 2050 yrs in upper Colombo water shed by increase 3.15 39.12% ((/y)mm/yr) Last 50 yrs Dry zone rainfall 10% decrease The reducing Decreasing R/F increase upto of dry zone trend will trend in 13 out 2050. annual runoff continue at of 15 stations with respect to 16.6% next 21 island wide 1961 ‐1990 yrs base line in 2050 Actual Model NWSDBModel 2009 Actual 12/22 ¾Rainfall variations (floods and droughts) ¾Increased salinity in the coastal belt water ¾Soil erosion ¾Soil moisture reduction due to evaporation ¾Water quality problems ¾Ground water depletion Is there a way out ?

NWSDB 2009 13/22 Distribution of dry zone tanks (in use and abdbandone d)

Manchanayake P. and Bandara C.M.M. (1999)

NWSDB 2009 14/22 Survey Department Sri Lanka NWSDB 2009 15 ‰Refurbishment of ancient tank system • Retain more water •Feed ground water aquifers ‰Wet zone •Preservation of marshy lands which will make the water flow slow

‰Trans basin diversions

‰Dedicated drinking water storage tanks for the wet zone . • Studies on Attanagaluoya, Kelani Ganga, Kaluganga and Mahaoyaare in progress ‰Catchment preservation to reduce soil erosion and improve soil moisture retention ƒAidAvoid “i“pine t”tree” plttilantation ƒAvoid expansion of Tea plantation ƒPollution control by providing better sanitation, avoiding industrialization ƒPreservation of natural forest in the hills ƒImplementation of traditional means of soil erosion control

NWSDB 2009 16/22 ‰Restrictions on land use to reduce run off coefficient

‰Implementing soil conservation techniques

‰Popularizing rainwater harvesting as a tool for overcoming droughts and diseases such as chronic renal failure.

‰ Ground water improvement with enhanced recharging and small scale treatment

NWSDB 2009 17/22 WITHIN THE ORGANIZATION

¾ Lack of overall understanding on climate change phenomena ¾Lack of staffing/facilities on water resources and water quality monitoring ¾Reluctance to initiate new ppgrograms due to lack of budget

NATIONAL LEVEL

¾ Lack inter organizational initiatives and coordination ¾Lack of integrated water resource assessment and planning ¾Lack of adequate environmental quality assessment and strong pollut io n cont ro l mech ani sm

NWSDB 2009 18/22 •Interagency expert panel to discuss climate change effects and adaptation measures based on water sharing among stakeholders. This panel should meet frequently to solve problems encountered by different agencies.

•Creation of information centre on climate change effects with the objective of creating and sharing data among stake holder organizations.

•Detailed studies based strategies to prioritize water utilization among irrigation, power and drinking water needs

NWSDB 2009 19/22 •Independent manpower development strategy to achieve the objectives of data collection, processing and producing information on climate changeeffects.Separate funds shall be available for implementation this kind of activity.

•Development of land use policy to cover protection of cascade tank system, protection of water storageinlow lying lands and marshes and protection of upper catchments

•Polices such as citing of industries, rain water ppyolicy etc. are also important NWSDB 2009 20/22 References

1. Manchanayake, P. and Bandara, C.M.M. (1999), Water Resources of Sri Lanka, National Science Foundation, Colombo.

2.Jayawardena, H.K.W.I., SdSonnandara, D.U.J. and Jayewardena, D.R. (2005) , Trends of Rainfall in Sri Lanka over the Last Century, Sri Lankan Journal of Physics, Vol.6 (2005) 7‐ 17.

3. De Silva, C.S. (2009), Impact of Climate Change Predictions on Food Production in Sri Lanka and Possible Adaptation Measures, Abstracts of the National Symposium on Promoting Knowledge Transfer to Strengthen Disaster Risk Reduction & Climate Change Adaptation, BMICH, Colombo, p7.

4. Wijesekera, S. ,IWRM as a tool for Adaptation to climate change http://www.nahrim.gov.my/wkh/PDF%20WKH/ToT/1.%20Presentation/Day%201/ accessed 9th August 2009.

5. Survey Department, Sri Lanka.

6. Corporate Plan 2007‐2011, National Water Suppl y & Drainage Board

NWSDB 2009 21/22 NWSDB 2009 22/22