Uncertainty analysis of HEC-HMS parameters using the GLUE methodology in Dez Dam watershed

This study represents the application of a generalized likelihood uncertainty estimation (GLUE) technique for automatic calibration of the well-known Hydrologic Engineering Center-Hydrologic Modelling System (HEC-HMS) model. For this purpose, the GLUE method was used in calibration of the HEC-HMS model built for Dez Dam basin located in south-west of Iran. From the three selected events, first event was used for calibration and all events were used for uncertainty and sensitivity analysis using GLUE approach. Model calibration showed that the developed model is a suitable model for simulation of flood with R2 and Nash-Sutcliffe Efficiency of 0.9 and 0.887, respectively. Sensitivity analysis of the model based on the four parameters of the Green Ampt method indicated that model does not show the same sensitivity on the same parameter in different events. For instance, saturated hydraulic conductivity has the greatest influence on the model of event 1 and model of event 3 is more sensitive to saturation suction at the wetting front and porosity. Uncertainty analysis using posterior distribution describes the uncertainty of estimation after taking into account information provided by the various flood events. Overall, the GLUE analysis showed that there is a significant uncertainty associated with hydrological modelling that is due to multiple sources of errors. Also, this method can be used for calibration of hydrological models like HEC-HMS