Coupling WRF with HEC-HMS for streamflow forecasting in typical mountainous catchments of northwestern Iran

Abstract Nowadays, with the increase in the frequency of extreme rainfall events, the alerts provided by real-time flood forecasting systems are becoming essential to provide accurate and timely information for emergency response. This study uses the Weather Research and Forecasting (WRF) model and the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) to assess heavy rainfall and runoff forecasting. The models were applied to the upstream basin of Shahid Kazemi Dam, Zarineh-Rood River, located northwest of Iran. The predictability of the WRF model with different microphysics, cumulus (CU), and planetary boundary layer (PBL) parameterizations is evaluated to identify the best set of physics parameters and optimize WRF for forecasting heavy rainfall events. The HEC-HMS model was calibrated by comparing its results with the data observed at gauge stations. The output rainfall data from the top 9 configurations of the WRF model were used as rainfall input in the calibrated HEC-HMS model to investigate the importance of the physical parameterization of the WRF model in runoff forecasting, and the results were examined using statistical indices. Kessler, MYJ, and Grell 3D schemes show the best results for microphysics, CU, and PBL. Consequently, this configuration is recommended for short-term rainfall forecasting tasks in northwest Iran. However, the accurate performance of the WRF model alongside HEC-HMS depends on choosing the best configuration. Still, optimal schemes for precipitation forecasting do not always provide the best estimates for runoff in the basin. The findings of this research could aid in developing a dynamic atmospheric-hydrologic integration system, enhancing flood prediction accuracy across various watersheds and climatic conditions.