Effect of land use land cover changes on hydrological response of Punpun River basin.

The present study assessed the hydrological response of land use land cover (LULC) change on the Punpun River basin. High-resolution gridded rainfall and temperature data from the years 1995 to 2020 have been used in the Soil and Water Assessment Tool (SWAT) in the Geographic Information System (GIS) to analyze the hydrological response of the Punpun River basin and water balance components. Hydrological Response Units (HRUs) have been created for the basin. Each HRU is based on a distinct combination of soil, slope, and land use. Five SWAT models have been prepared based on the LULC of every 5-year interval to simulate the basin's hydrological response. The period selected for calibration is 1995-2015 and for validation is 2016-2020 for the modeling of daily streamflow data. The observed and simulated streamflow was checked for performance indices of coefficient of determination (R), Nash-Sutcliffe Efficiency (NSE), and percent bias (PBIAS) on daily time steps. The results were found to be good with R = 0.72, NSE = 0.68, and PBIAS = 23.2 for calibration and R = 0.93, NSE = 0.77, and PBIAS = 19.8 for validation. The study reveals that 7.01% of evapotranspiration (ET) was increased from 1995 to 2020 with increase in agricultural area of 21.86%. It was also found that built-up area, surface runoff, and water yield have been increased by 9.14, 14.43, and 17.40%, respectively. Further, the groundwater contribution of the basin was decreased.