Climate Change Impacts on Water Resources Case of Sri Lanka

Abstract

This paper presents an analysis of long term trends of climatic variables in Colombo and its impact on water resources. Long-term trends of rainfall have been analysed and it is evident that the dry and wet days are changing. There are more dry days than wet days. The large standard deviation is occurring annually recently enhances the problem. The analysis indicates that in the southwest monsoon and the second inter-monsoon season, a large rainfall occurs and could then easily give rise to flooding. Meanwhile, several extreme weather events also occur in that time. This phenomenon can cause flash floods and drainage system may not be able to cope. The population in Colombo region is rising every year. Due to the high population density in the north of Colombo, water scarcity may manifest even though the rainfall in Colombo is sufficient. In addition, the demand of fresh water and water quality should all be considered. Due to increased population and greater urbanization in city micro climate conditions could evolve and temperature may increase. The trend of temperature is increasing with 0.0164℃/year and R 2 = 0.67. Accordingly, the average temperature in April and August is higher than other months. The evaporations in those months are higher than the rest and hence elevated precipitation as well. The flood in lower part of Kelani River is becoming more frequent. This paper analyses these variables, develop algorithms for future prediction and suggest solutions to better manage water resources.