Predicting the Water Availability Under Land Use Scenarios and Climatic Change for Micro-hydro Power Generation in Sri Lanka Using PRA Tools

The objective of this study was to study the impact of land use and climatic change on the water availability for off-grid rural micro-hydro power generation. Five micro hydro sites from five districts were selected and land use features were identified using PRA tools namely, transact diagrams, land use maps and direct observations. Rainfall data of the sites were collected to characterize the sites. Present study clearly indicates that land use factors have to be considered when estimating water yield for micro hydro development. The difference between rainfall and water yield is high especially when catchments are covered with tree (taller) vegetation. Lowering of rainfall due to climatic change is going to have differential impacts on the actual water yield of the catchments depending upon the nature of its land use. Introducing water saving land use may be an option to increase the water yield. However, land use at a particular place is determined by many factors, which often have little or no relevance to hydrology of the areas.