The Hydrologic Modeling System HEC-HMS is designed to simulate the precipitation-runoff processes for watershed systems. It is designed to be used in a wide range of geographic areas to solve the wide range of problems. This includes large river basin, water supply and flood hydrology and small urban or natural watershed runoff. In this study HEC-HMS model was applied to develop the rainfall-runoff model applications in TaghsimAb and DareMoradbeig catchments in Hamedan, Iran. The model also incorporates ARC-GIS extensions, HEC-GeoHMS and ARC-Hydro tools for the spatial analysis of the watershed. The input data of this model is Precipitation, temperature, radiation, humidity and wind speed from 01/Jan/2014 to 31/Dec/2016 as daily input data. The Nash-Sutcliffe efficiency, difference between observed and simulated peak discharges and Root Mean Square Error (RMSE) of this model were about 0.233, 0.90 and 1.5 for TaghsimAb watershed, respectively; these factors were about 0.345, 0.80 and 0.2, for DareMoradbeig watershed, respectively; and also the above factors were about 0.512, 0.70 and 1.3, for Tooijin watershed.
