Assessing hydrological and water quality parameters in the Hathmati Watershed using the SWAT (Soil and Water Assessment Tool)

Abstract The study is conducted on the Hathmati River, which is the principal tributary of the Sabarmati River, one of Gujarat's biggest rivers. Indicators of water quality such organic N, organic P, NO3, NH4, NO2, total N, and total P were compared between the observed values in the watershed and the streamflow models. For monthly streamflow and monthly nitrate during the calibration period of 1999–2012, and for 0.87 and 0.56 for the validation period of 2013–2020, respectively, the Nash–Sutcliffe efficiency was 0.89 and 0.79. The measured water quality data at three locations in the watershed were largely compatible with their corresponding modeled values, while the agreement varied by nutrients. Using the parameters used to forecast the hydrological and water quality responses in the watershed region, the Soil and Water Assessment Tool model faithfully duplicated the hydrological and water quality conditions in this agricultural watershed. The results of the modeling indicated that nutrients are one of the key determinants with regard to the quality of the water, in accordance with the current land use and management practices in the watershed. Management practices should be implemented in order to reduce the nutrient load and meet the watershed's requisite water quality standards.