Site characterization is crucial for the location and design of dams because it offers data for risk assessments and the planning and implementation of remediation measures. This study looked into the potential use of GIS-based methods for the characterization of dam sites. Satellite pictures were used to verify the catchment delineation results. The catchment slope, the number of networks in the sub-basin, and the land surface cover were all taken into consideration while choosing a location for a dam. From the findings, five possible dam site locations — Kisarawe (upstream), Magomeni, Kinyerezi, Jangwani, and Pugu sub-catchments — were identified. The Kisarawe sub-basin upstream has the largest prospective location (covering an area of around 89.89 km2) since it has a less populated and developed area, which would allow for enough room to construct a dam while protecting the downstream from frequent flooding. According to the capacity and other requirements of the receiving stream downstream, the chosen dam locations could hold approximately 75.15% of the runoff produced in the catchment before releasing it at a controlled rate. The outcomes of the study demonstrate further the effectiveness of geographic information systems in determining the characteristics of dam sites and in designing sustainable dams that take land surface cover into account.