Assessment of Water Availability in Chennai Basin under Present and Future Climate Scenarios

Abstract

Climate change may significantly impact the hydrological processes of a watershed system and lead to water scarcity or increased flooding. It may also cause serious problems to humans including loss of biodiversity and risks to the ecosystem. Quantifying and understanding the hydrological response to a changing climate are necessary for water resource management and formulation of adaptive strategies. In this study, changes in water balance components of the Chennai Basin under present and future climate scenarios had been assessed using Soil and Water Assessment Tool (SWAT). High resolution climate outputs (0.25° × 0.25°) from PRECIS regional climate model for present (1961–1990 BL), mid-century (2041–2070 MC) and end-century (2071–2098 EC) under the IPCC SRES A1B emission scenario were used to assess the hydrological changes in the Chennai Basin. The study had determined the present and future water availability in space and time without incorporating any man-made changes like dams, diversions etc. The results indicated a decrease of precipitation in future scenarios as a result decrease of total water yield and ground water flow component in mid-century and end-century. Though both of these scenarios showed decreases in water balance components, the decrease in end-century would be lesser than the mid-century. In the season-wise analysis, the ET would be increased in winter and post monsoon seasons. Water yield had shown decrease in all the seasons of the mid-century scenario and increase during the EC winter and summer seasons.