The main objective of this study is to investigate the potential for collecting floodwater from Al-Shiwiaja depression in the Wasit Governorate, eastern Iraq. The floodwater data used in the study were collected during a flood in the study area on November 14, 2015. One proposed solution to this issue is to build a reservoir. A reservoir is to be constructed upstream of the depression, with a drainage canal constructed at its base to direct any surplus water toward the Tigris River via the Um Al-Jery regulator. The GIS, HEC-HMS, and HEC-RAS were used to simulate floodwater in the depression. To validate the model, the flood volume was calculated using the flood routing method and compared with the model. The results show a good agreement, with the maximum difference being 8.1%. The results of the study indicate that water harvesting and flood management could be enhanced by integrating hydrological and hydraulic modeling with remote sensing techniques. The research shows that the proposed solution effectively reduces floodwater risk and addresses pollution sources, especially sewage, as well as the high sediment loads accumulating in the natural depression.