Development of a rainfall-runoff model, its calibration and validation

In this study a rainfall-runoff model was developed based on water balance equations. Input to the model is precipitation and potential evapotranspiration (both on monthly basis). Output from the model is the simulated runoff at the watershed outlet. Five parameters were adopted for description of the characteristics of drainage area. These parameters are estimated using the Downhill Simplex Method. The model was calibrated and tested for four watersheds. Statistical results showed that the model preformed well. The correlation co-efficient between the simulated and measured data was on the range of 77% to 93%.