The study of water resources use to manage, assess and simulate these important natural resources. In Tamirabarani basin the land use pattern around the flood basin area and population density increased. So many area of the river is occupied by the urbanization and deforestation. The climatic conditions also varied. This various problems are affecting the surface water flow. The previous methods of surface water flow involve many manual methods and calculations. The ArcSWAT used to create the streamflow model for the changes in the land use pattern and climatic condition. ArcSWAT can be used to generate valuable information for decision making by producing maps with model output spatially overlaid on other important GIS data.  In this ArcSWAT used to develop the model for the water management using the HRU (land use, soil, and slope) units.