It is impossible or extremely difficult to alienage climate change from sustainable management of water resources. Most research has already confirmed that the quantity of rain received on an annual basis has not changed significantly over the years. Numerous research reported from various parts of the world indicates that the dry months get drier and the wet months get wetter. When matching the aforesaid outputs, it is clear that the rainfall intensities need to change. About spatial variability too, there are many remarks, conclusions and predications.
Sri Lanka being a green country in which almost the entire dry zone is dependent on agriculture, needs to identify whether its catchments would generate the same streamflow throughout the year. Hence It is necessary to capture the behavior of the source areas corresponding to the minor reservoirs, small and medium scale reservoirs in the dry zone.
Sri Lanka, similar to many countries in the region, is very rich in rainfall data collection. However, a catchment scale, long term data analysis and results interpretation for adaptation measures on water resources infrastructure, requires significant strengthening and urgent action.
Therefore, an urgent policy decision as a climate action must be taken to identify critical watersheds and then to evaluate the long term rainfall and streamflow behaviour on monthly, seasonal and annual scales in order to identify respective catchment scale trends and make attempts to establish relationships even though the processes are non-stationary.