Due to climate change and facing water scarcity, especially in developing countries, the need for managing this valuable resource is more important than ever. The main aim of this research is to optimize water allocation, store water resulting from rainfall, and reduce flooding. Considering the increase in population, these problems and challenges are becoming more apparent. Therefore, in this study, using the concept of a sponge city, flood-prone areas of Sanandaj city were identified, and the necessary steps, preliminary studies, and research for implementing this concept were carried out. Based on this, in this research, the topographic status of the area under study was investigated using Digital Elevation Model (DEM), and then, water catchment areas and low-lying areas were identified using GIS software. Subsequently, the infiltration rate of water in the soil of Sanandaj city for different soil types was calculated, and the amount of precipitation was estimated. Using the NDVI map and land use map, buildings and roads were determined by QGIS software, and the Curve Number (CN) was calculated along with the volume of runoff resulting from rainfall. Furthermore, the amount of runoff obtained from precipitation in 2021 in the urban area has been allocated to various urban, industrial, and agricultural uses using the WEAP model.