Hydrologic Impact Evaluation of Land Use and Land Cover Change in Subbasins of Tapi River Using SWAT Model

The current research is based on the comparative analysis conducted using land-use maps of 2005 and 2015. SWAT simulations are undertaken on a monthly time scale to estimate runoff for associated rainfall. The coefficient of correlation (R2) and Nash–Sutcliffe efficiency (NSE) for rainfall and the accompanying runoff for the calibration period of 10 years (1988–97) are determined to be 0.99 and 0.99 respectively at Gidhade station and 0.95 and 0.9 for Sarangkheda station. And for the next 7 years (1998–2004) of the validation period, values of R2 and NSE are 0.99 and 0.99 and 0.99 and 0.98 for Sarangkheda and Gidhade stream gauge stations. The above-mentioned results are comparatively similar for both land-use maps for 2005 and 2015. Based on model predictions, it is found that the annual surface runoff reduced marginally while the evapotranspiration increased, while baseflow and deep aquifer recharging remain unchanged. The surface runoff has decreased by 3.23% in the ten years, water in shallow aquifer returning to root zone has lowered by 0.34%, and evapotranspiration has increased by 1.07%. In terms of land-use classes, there has been a significant increase in rangeland and a decline in agricultural land.