Climate Change Impacts and Adaptation Measures in Giritale Reservoir in Polonnaruwa Sri Lanka

Abstract

Climate change is one of the most important global environmental challenges, which affects the overall system by affecting food production, water supply, health, energy, etc. For study purpose Giritale reservoir in Polonnaruwa district of dry zone in Sri Lanka was selected. Catchment area of the reservoir is 24.3 sq.km and command area is 3075 ha. Data for the reservoir was collected from irrigation department, Colombo and 6 year (2010-2015) rainfall data collected also from irrigation department. This study investigated the impact of climate change, adaption and mitigation measures reservoir system. After a review three scenarios were identified. Scenario 1 rainfall increase 15.8% and temperature increase 8% and scenario2 rainfall increase 14% and temperature increase1.6% and scenario 3 is rainfall is projected to increase by 48% for the Southwest Monsoon by 2050 and Northeast Monsoon, which occurs in the drier northern region, is predicted to decrease by 27–29%. For the worst scenario four adaptation measures were proposed. Among the four only two adaptations could be quantified, and the best adaptation measure was identified. Among scenario option’s, the scenario 2 is the worst scenario and adaptation measure taken for scenario2consist of two options. Option1 is changing the crop type and option 2 is increasing the canal efficiency. For option 1 105 days paddy for Maha and Yala was taken and also green gram for both Maha and Yala was considered and for option2 canal efficiency increased by 10% . Therefore comparing the results adaptation use of green gram improved the cropping intensity by 13%.For verification of result actual rainfall data is not enough and also for predicting the climate trend. Future climate projections indicate that the climate is changing and impacts on agriculture sector can be expected and Worst climate change scenario for the Gritale scheme is when increasing rainfall 14% and also increase the evaporation 6.4%.