University of Tehran Press Journal of Ecohydrology 2423-6098 5 2 2018 06 22 Comparison of the Three Different Abstraction Estimation Methods of Rainfall in HEC-HMS Model in Runoff Simulation (Case study: Kermanshah Gharasoo watershed) Comparison of the Three Different Abstraction Estimation Methods of Rainfall in HEC-HMS Model in Runoff Simulation (Case study: Kermanshah Gharasoo watershed) 433 447 65756 10.22059/ije.2018.232808.591 FA Milad Moradi M. Sc. Graduate of Water Resources Engineering, Department of Water Engineering, Faculty of Agriculture, Shahid Bahonar University, Kerman, Iran Yaghoub Dinpazhouh Department of Water Engineering, University of Tabriz, Tabriz, Iran Somayeh Azizi M. Sc. Hydraulic Structures, Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz Journal Article 2017 05 22 Rainfall-runoff modeling is one of the key items that considered in hydrology to achieve flood characteristics. In this study, HEC-HMS model performance was evaluated using the SCS-CN, Green-Ampt and Initial and Constant infiltration methods in predicting runoff volume, peak flow and time to peak, in simulation of rainfall- runoff hydrograph at Gharasoo watershed, located in Kermanshah province. Eight rainfall–runoff events were simulated by HEC-HMS model and compared with the corresponding observations events. Results shown a well accuracy in predicting runoff volume (R2=0.84, E=0.81 and CRM=0.06) was achieved using the SCS-CN method (after calibration). However, Peak flow was better estimated using the Initial and Constant method (R2=0.96, E=0.95 and CRM=0.01). Furthermore, shape of the calibrated hydrographs were very similar to the observations hydrographs for both SCS-CN and Initial and Constant methods. However, adopting the Green-Ampt method, showed low reliability in total runoff volume and peak flow estimating. Model accuracy in estimates of modeled the time to floods peak, were evaluated by comparing observed and simulated values through the selected approaches, so that the results of time to floods peak showed the highest reliability in SCS-CN method (6.36%). Rainfall-runoff modeling is one of the key items that considered in hydrology to achieve flood characteristics. In this study, HEC-HMS model performance was evaluated using the SCS-CN, Green-Ampt and Initial and Constant infiltration methods in predicting runoff volume, peak flow and time to peak, in simulation of rainfall- runoff hydrograph at Gharasoo watershed, located in Kermanshah province. Eight rainfall–runoff events were simulated by HEC-HMS model and compared with the corresponding observations events. Results shown a well accuracy in predicting runoff volume (R2=0.84, E=0.81 and CRM=0.06) was achieved using the SCS-CN method (after calibration). However, Peak flow was better estimated using the Initial and Constant method (R2=0.96, E=0.95 and CRM=0.01). Furthermore, shape of the calibrated hydrographs were very similar to the observations hydrographs for both SCS-CN and Initial and Constant methods. However, adopting the Green-Ampt method, showed low reliability in total runoff volume and peak flow estimating. Model accuracy in estimates of modeled the time to floods peak, were evaluated by comparing observed and simulated values through the selected approaches, so that the results of time to floods peak showed the highest reliability in SCS-CN method (6.36%). https://ije.ut.ac.ir/article_65756_e17092e0ea959c490735923be32e10f0.pdf