Hydrological modeling for the Bharathapuzha River basin of South India using SWAT model

The main objective of the study is to ensure the well-being of future generations based on land and water resources. Hydrological modeling is a dependable method that the scientific community can trust for the efficient utilization of these two highly precious resources. Out all the different hydrological modeling models, the Soil and Water Assessment Tool (SWAT), which is a physically based distributed model, has acquired significant popularity. This study was performed on Bharathapuzha River basin, an intricate river basin located in South India, which passes through the states of Kerala and Tamil Nadu. The Digital Elevation Model (DEM), the Land Use/Land Cover (LULC) map, and the soil map were utilized to articulate the watershed, which led to the creation of 37 sub-basins and 312 Hydrologic Response Units (HRUs) applying a threshold of 5:10:10 for Land Use, Soil, and Slope %, respectively. By utilizing the input of weather data on rainfall and temperature, a simulation was conducted to determine the runoff at the Kuttipuram outlet. The calibration period spanned from 2000 to 2012, whereas the validation phase included the years 2013–2017. Several performance indicators, such as NSE (Nash-Sutcliffe Efficiency), PBIAS (Percent Bias), and RSR (RMSE-Observations standard deviation ratio), were considered. The values of NSE, PBIAS and RSR for calibration period were found to be 0.6, −10.6 and 0.62, whereas for validation period the same were obtained as 0.54, −13.6 and 0.68, respectively. The findings demonstrate that the calibrated SWAT model is suitable for future investigations in the basin. • The major portion of study area comes under agricultural land (52.72 %). • The loam soil is the predominant soil type found in the Bharathapuzha basin. • CN2 is the most sensitive parameter for stream flow simulation. • Performance indices NSE, PBIAS and RSR show satisfactory stream flow simulation.