Abstract:Advancements in computer techniques with a Geographic Information System (GIS) interface have greatly contributed in simulating river basins with a reasonable level of accuracy. It becomes possible to analyze and model various aspects of a river basin, such as water flow, land use, and hydrological processes. Water is essential for sustaining life.Previous studies reveals effective watershed management requires an understanding of the impact of rainfall in the catchment area, but due to poorly gauged river basin it becomes difficult to predict hydrological response. In this context HEC HMS model is used to simulates surface runoff in different watersheds.The study simulate Wainganga river basin, geographically located between longitude 78°0’–80°45’ E and latitudes 19°41’–22°50’ N.The model utilizes eighteen years data for rainfall extracted from IMD (Indian Meteorological Department) with 0.25X0.25 grid. Similarly evapotranspiration and observed discharge is extracted from India-WRIS (Water Resource information System).Shuttle radar topography mission (SRTM) dataset with digital elevation model (DEM) of 30 m X 30m spatial resolution), extracted from USGS (United States of Geological Survey ) was a input to HEC HMS 4.10.Different approaches with changing parameters was implemented for suitable simulation.SCS curve number method with Muskingum routing is implemented for study. The purpose of study is to compare calculated and observed discharge and test model performance.NSE is used for testing performance. The results shows a satisfactory performance with, Nash efficiency coefi cients(NSE) above 0.7 for basin.The description outlines ,model can be used for assessing behavior of large river basin.