Estimation of flood hydrographs in ungauged watershed with Gamma synthetic unit hydrograph model

Estimation of flood hydrographs in the ungauged watersheds is a challenging issue in flood planning and management. Various models have been developed in this filed and it is necessary to evaluate the performance of models developed in different regions of the world with different climatic, hydrological and physiographic features in order to comment on their performance in different regions. The Gamma synthetic unit hydrograph model is a developed model for estimating flood hydrographs in the ungauged watersheds with limited studies in the world. In this study, the Gamma synthetic unit hydrograph model for estimating flood hydrograph characteristics in Qareh-Sou watershed located in Kermanshah province in Iran has been investigated. Criteria for percentage error in peak discharge, percentage error in volume, mean absolute error, mean bias error, coefficient of determination and Kling-Gupta were estimated to evaluate the accuracy of simulation results. Based on the results, the mean values of the criteria expressed are 6.28, 17.4, 0.89, 0.54, 0.74 and 0.75, respectively, indicating that the Gamma synthetic unit hydrograph model is quite accurate in estimating the characteristics of the flood hydrograph in this study. In addition, the visual comparison of computational and observational hydrographs illustrates the remarkable accuracy of the Gamma synthetic unit hydrograph model in estimating the shape of flood hydrographs in the studied events.