For accurate and easy estimation of runoff and sediment yield can be done by using physical based continuous hydrological model. Among the many hydrological model Soil and Water Assessment Tool (SWAT) is the more promising model for simulations in predominant agricultural watershed. Moreover the model is better in assessing both spatial and temporal variability of the hydrological process under very large watershed. The present paper provides the methodology used by the SWAT for calculation of runoff and sediment yield. During model setup input data required by the model, sensitivity parameter analysis, calibration and validation are discussed in detail. In sensitivity analysis in case of stream flow simulation, parameters such as initial SCS Runoff curve number for moisture condition II (CN2), Base flow alpha factor (ALPHA_BF), Groundwater delay time (GW_DELAY), Threshold depth of water in the shallow aquifer required for return flow to occur (GWQMN) and Surface runoff lag coefficient (SURLAG), etc., which significantly impact the discharge simulation.

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