Climate Change Impact Assessment under CORDEX South-Asia RCM Scenarios on Brahmani-Baitarani River Basin

Abstract

This study attempts to assess the impact of climate change on Brahmani and Baitarini river basin using a GIS-based semi-distributed model Soil and Water Analysis Tool (SWAT). The SWAT model uses various physiographic features such as slope, soil and land use classes to estimate the various water balance components of the river basin for the baseline period (1980-2010) and future climate scenarios (2071-2100). Sensitivity analysis has been carried out to identify the most critical parameters of themodel. The model was calibrated (1980-2000) and validated (2001-2010) using the observed average daily discharge data. The model performance was evaluated using the coefficient of determination (R2), Nash-Sutcliffe efficiency (ENS). The data from CORDEX South Asia RCM model for RCP 4.5 and 8.5 scenarios developed by IITM was used in the SWAT model to evaluate changes in various water balance components. Overall the SWAT model performed satisfactorily having Nash-Sutcliffe efficiency value of 0.72 and 0.65 for calibration and validation respectively. Results show an increase in average annual temperature (3.1°C), average rainfall (+10.7 mm/year).This corresponds to the increase in in the annual streamflow (110%-117%), evapotranspiration (48%) and water yield (159%)