Assessment of GIS Based Water Balance Components in a Semi-Arid Region of Southern India

Water resource management in semi-arid regions is challenging due to variable rainfall and high evapotranspiration rates. This study estimates the water balance components—runoff, evapotranspiration, interception, and groundwater recharge—at a fine spatial resolution (30 × 30 m) in the Chitravathi River basin, India, across diverse land uses and soil types on both seasonal and annual scales. Digital maps of soil type, elevation, slope, groundwater levels, land use, and meteorological variables (precipitation, wind speed, number of rainy days, and temperature) were used as inputs for the raster-based water balance model WetSpass-M (Water and Energy Transfer between Soil, Plants, and Atmosphere under a Quasi-Steady State) to simulate the water balance components from 2000 to 2023. WetSpass-M model was calibrated and validated using seasonal discharge data, achieving R2 values of 0.84 and 0.82 and NSE values of 0.81 and 0.80 during calibration and validation, respectively. Results indicate that annual precipitation in the basin contributes 14% to surface runoff, 45% to evapotranspiration, 4% to interception, and 37% to groundwater recharge. This comprehensive methodology provides valuable understanding of water balance dynamics, which are essential for the sustainable management of water resources in semi-arid regions.