Investigating the Impacts of Climate Change and Adaptation Options in Handegama Tank for Irrigation Water Management

Abstract

Under the changing climate, major effects are likely to arise from changes to the freshwater resources systems. The water resources under Hadegama scheme are already stressed and under climate change the availability of irrigation water is expected to become a major issue. This study would help investigate impacts of climate change and adaptation options in Handegama tank for water security. Future scenarios for climate change were selected based on predicted climate information from literature and a reservoir operation was performed under changing irrigation demand. Behavior of the system pertaining to the changes in climatic parameters such as rainfall and evaporation is useful for planning purpose and identifying possible adaptation measures. The worst climate change scenario for Handegama tank was identified as the fifth scenario with decrease in the annual rainfall by 14% and an increase in temperature by 2°C while increasing evaporation by 8 % by 2050. The cropping intensity under this scenario reduced from 1.53 to 1.25, a decrease of 28%. The identified adaptation options were crop diversification and improvement of canal efficiency; both of them increased the cropping intensity by almost 18 %. Reduction in available water under the worst climate change scenario would cause a 28 % reduction in the cropping intensity. These results indicate the need for adaptation under climate change. The adaptation options identified in this study helps to increase the cropping intensity thereby proving to be beneficial to the water users within the system.