Potential Changes to the Water Balance of the Teesta River Basin Due to Climate Change

This study is carried out to assess the potential changes to the water balance of the Teesta River basin due to climate change. A semi-distributed hydrological model of Teesta river basin has been developed using SWAT (Soil Water Assessment Tool). After assessing the results of GCM solutions for 2080s, four scenarios has been selected for detail analysis. They are: Wettest, Driest, Warmest and Coolest. Among the selected scenarios, for the wettest scenario the precipitation had increased by 11.71% while it decreased by 1.76% for the driest scenario. The increase in temperature for the coolest and the warmest scenario is found to be 2.24？？C and 5.34？？C. The developed hydrological model of 1998-2013 timeframe served as the base model output to be compared against climate change model results. Comparing the water balance of the climate change model with the base model, it has been found that the monsoon season will become more wetter (as much as 48% increase of precipitation) and the dry season become more drier (as much as 43% reduction of precipitation) due to climate change for all the climate change scenarios. The flow comparison at the Dalia point, upstream of Teesta Barrage for different climate change scenarios shows similar kind of trend to that of the water balance comparison. The general trend emerging from the flow analysis is that the Dalia point will experience a more severe shortage of water during the lean season where, as much as 25% decrease of flow has been found even without any upstream controls