Scoping potential dams: utilising remote sensing products to analyse topographic characteristics, runoff-to-storage ratio, and sedimentation—a Port Sudan case study

Abstract When assessing sites for water harvesting structures, it is common to evaluate multiple locations using earth observation datasets before committing to detailed assessments. Traditionally, this practice relies on limited metrics, primarily topographic slope or wetness index. In this study, we present a comprehensive approach tailored to Port Sudan, a city urgently needing sustainable water resources. We defined the area of interest and used satellite-derived terrain data to identify over 25,000 potential dam sites, filtering out locations using Strahler stream order. We then used the geospatial tool ‘SiteFinder’ to determine dam sizes and reservoir dimensions for potential schemes, ranked for suitability using an Analytical Hierarchy Process (AHP) based on five local topographic characteristics. Next, we applied a rainfall-runoff model that integrates transmission losses to estimate runoff at each potential site. Schemes were filtered to retain only those predicted to receive sufficient runoff, based on the ratio of annual runoff volume to storage capacity. We then modelled storage capacity loss due to sediment retention to retain schemes with less than 2% per year volume loss to sedimentation. This resulted in 55 favourable schemes being identified. This approach may interest planners involved in water harvesting site selection studies, considering criteria such as storage volume, dam size, runoff, and sediment retention. Results are presented within a GIS environment, enabling the inclusion of additional criteria in the final decision-making process.