Modeling stream flow rate and sediment concentration for identification of critical watershed of Seonath sub-basin using SWAT model

Land degradation and deterioration of water resources is most significant issue due to the soil erosion in watershed areas. Hydrologic model of Soil and Water Assessment Tool (SWAT) is used in this study to model the flow rate and concentration of sediments of a stream with least-uncertainty among the parameters of Seonath sub-basin for the period from 2003–2013. The stream flow rate and sediment concentration of the study area was calibrated and validated with the application of SWAT model. Other than climatic parameters, most of the input parameters were extracted from ArcGIS environment which is integrated with the model and by providing different thematic maps. The calibration result of simulating stream flow rates in year 2003–2009 were found to be satisfactory since coefficient of determination (r²) = 0.89, Nash-Sutcliffe coefficient (ENS) = 0.87, PBIAS=13.28 and Index of Agreement (d) = 0.96, respectively. Also, significant performance of model for sediment concentration was found for calibration period with ENS = 0.88, d = 0.82, PBIAS = 5.59, r² = 0.94. During validation period (year 2010–2013) for monthly time step ENS = 0.91, PBIAS = 9.14, r² = 0.93 and d = 0.97 was found to be very good for stream flow rates. Similarly, for sediment concentration ENS = 0.92, PBIAS = 5.9, r² = 0.97, and d = 0.91 was found, which indicate very good model performance. The estimated amount of sediment yield of Seonath sub basin were found to be varied between 0.06 and 92.37 t/ha/yr, with an average rate 23.56 t/ha/yr. The soil erosion index map of Seonath bus-basin was prepared which indicated that area of very high soil losses in watershed. Conclusion of this study indicate that the ArcSWAT model can simulate flow rate and sediment concentration accurately and can be applied for effective planning and management of soil and water availability in Seonath sub-basin.