This study addresses the need for accurate hydrological data in arid and semi-arid regions by estimating runoff volume in the Jerash Basin, Jordan, using advanced geographic information systems (GIS) and the Soil Conservation Service Curve Number (SCS-CN) method. The primary goal is to enhance flood risk assessment and support sustainable water resource management in the Jerash Basin by providing accurate hydrological data. The research integrates high-resolution digital elevation models (DEMs) and spatial data to analyze soil and land use characteristics, applying the SCS-CN method within a GIS environment to estimate runoff volume, drainage density, and concentration time. Findings reveal a general CN of 87.83, indicating high runoff potential, a drainage density of 12.60 km/km², and a concentration-time of approximately 222.48 minutes, suggesting a high susceptibility to flooding due to the short transit distance of runoff. The low relief ratio of 0.035 further highlights the basin's limited dissection and drainage capacity. These results demonstrate that accurate runoff estimation using high-quality digital data sources can significantly improve flood risk assessment and water resource planning in arid and semi-arid regions. A limitation of the study is its reliance on static data, which may not fully capture dynamic hydrological processes, and the findings are specific to the Jerash Basin, requiring adaptation for application in other regions. The practical value of this research lies in its scalable framework for flood risk assessment and water resource management in arid and semi-arid regions, informing decision-making processes related to infrastructure development, flood mitigation, and sustainable water resource planning. The originality of this study lies in its innovative application of GIS and SCS-CN methods in the Jerash Basin, a region with limited hydrological records, offering new insights into flood risk and water resource management. By applying these well-established tools in a data-scarce context, this research provides significant value for sustainable water resource planning and flood mitigation in arid and semi-arid regions.