COMPARISON METHODS GREEN & AMPT AND INITIAL AND CONSTANT RATE LOSS FOR ESTIMATE PRECIPITATION LOSS TO SIMULATION RUNOFF

In this study, by use of HEC-HMS model and comparison of results of different methods of runoff loss evaluation (Green & Ampt and Initial and constant rate loss) consider to various purpose function (percent error in peak and percent error in volume) tried to classify the methods. In this way, based on purpose function, the method with least difference percent of observed discharge to calculate discharge take place in first preference and other method take place in next preferences. Result show that, for two purpose function, Initial and constant rate loss method rather than in 70% of events, least difference percent of observed discharge was less than calculated discharge and it selected as optimum method for simulation of runoff.

Green & Ampt, precipitation loss, HEC-HMS model, constant rate loss, percent error in peak.