The study compares suggested dam sites for rainwater harvesting in the Al-Naft Valley, east of Diyala Governorate, Iraq, near the Iranian border. The digital elevation model, Operational Land Imager data, ArcGIS 10.8, Global Mapper 24, and Surfer 17 software were employed for this purpose. The watershed, predominantly in Iran 70% with 30% in Iraq, was of the sixth order, covering 1443 km². The total surface runoff volume was estimated at 320,000,000 m³/year using the SCS-CN method, which highlighted challenges due to international border crossings. The evaluation of the suggested dam sites depended on 11encompassed morphometric (stream order), hydrological (annual water income), geometric (reservoir capacity, average depth, surface area of reservoir, and safety factor), demographic (number of capita benefiting), economic (relative cost/ storage, road submerging by the lake, distance to roads) and geopolitical criteria (area of lake crossed international borders). Analytic Hierarchy Process and Weighted Sum Method were used for comparison, with input from 35 experts to weight criteria to evaluate six proposed sites (alternatives). The second, third, and fourth proposed dams are classified as large-sized, while the others are medium-sized. The third proposed dam emerged as the most suitable, offering a storage capacity of 165,000,000 m³, representing 51.5% of annual input water. To align storage with annual water input, multiple dams are preferred. The first, third, and sixth proposed reservoirs, with a total capacity of 237,000,000 m³, constitute 74% of the expected annual water input to the watershed.
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