Strategic Dam Locations for Enhanced Management of Water Resources, Cost Savings and Carbon Emission Reduction in the Southwestern Region of Saudi Arabia

The southwestern region of Saudi Arabia often experiences flash floods due to heavy rainfall. A total of 166 dams in this region have the capacity of 878 Million m³ (Mm³). The dams are used to control floods, recharge aquifers and to supply water for domestic and agricultural uses. The frequent flash floods in the southwestern region indicate the scope of water resources augmentation through runoff collection. The primary objective of this research is to enhance water resource management in the southwestern region of Saudi Arabia by identifying strategic infrastructure improvements that address financial and environmental impacts associated with drinking water supply systems. To achieve this, the study applies advanced hydrological modeling and geographic analysis, focusing on optimal dam location and capacity to manage runoff more effectively. By assessing factors such as runoff potential, storage requirements and cost–benefit impacts, this study establishes a methodological framework aimed at sustainable water sourcing and resource conservation in arid regions. In this study, locations of new dams were identified in five areas (Abha, Al-Baha, Bisha, Jizan and Khamis Mushait) in the southwestern region of Saudi Arabia. The watershed delineation, runoff estimation and reservoir volume quantification were performed using the watershed modeling system software, HEC-HMS hydrologic model and ArcGIS software. The uncertainty was incorporated through fuzzy rule-based modeling approach. For a storm event of 100-year return period, averages of runoff were estimated to be 16.1, 30.7, 2.6, 10.6 and 3.9 Mm³ for the watersheds in Abha, Al-Baha, Bisha, Jizan and Khamis Mushait, respectively. Use of runoff instead of desalinated water in these areas could save approximately US$ 18.4, 32.9, 4.1, 14.4 and 5.2 million, respectively, which could also reduce CO₂ emission by 255.5, 490.1, 50.6, 56.6 and 69.3 million kg, respectively. This study is likely to advance water resources management in Saudi Arabia through identifying the locations of new dams to capture flash flood-generated runoff in five areas. This study focused on runoff generation, collection, economic benefits through cost savings and environmental pollution abatement through carbon emission reductions, which are the advances in comparison to the previous studies on flood risks. The applications of fuzzy rule-based models incorporated uncertainties to better explain the runoff generation from flash floods.