Estimation of Instantaneous Peak Discharge Using GIUH, Snyder, SCS and Triangular Models: a Case Study of Central Alborz Watershed

The estimation of instantaneous peak discharge is important for watershed management because there is a insufficient climatic and hydrologic data in countries such as Iran. Researchers have been forced to link constant parameters (geomorphology) and variable parameters (hydrology) to models with minimum dependence on climatic and hydrologic data for hydrologic estimation. The present study used a synthetic unit hydrograph at three drainage basins in the central Alborz watershed (Kan, Amameh and Mehran) and compared the results with peak discharge in the study areas to derive the best model. The results of the instantaneous peak discharge estimation were similar for each drainage basin. A comparison of the models using relative mean error (RME) and root of mean square error (RMSE) for the three drainage basins showed that the mean RME for GIUH was 21.31, for Snyder was 82.25, for SCS was 227.34, and for triangular was 231.27. The mean RMSE for GIUH was 12.76, for Snyder was 17.05, for SCS was 42.84, and for triangular was 43.62. This confirms that the best estimation was produced by GIUH, followed by the Snyder, SCS and triangular models.