Sand Dam Suitability Assessment, A Case of the Lower Awash Basin, Ethiopia

Water security is a crucial issue in arid and semi-arid regions like the Lower Awash Basin, Ethiopia, where increasing population and economic development put pressure on limited water resources. This study evaluates the suitability of sand dam sites using a multi-criteria evaluation approach combined with geospatial techniques. Meteorological data were carefully tested for consistency and homogeneity through double mass curves, Pettitt’s test, and Mann-Kendall analysis. Key biophysical factors such as slope, stream order, soil type, land use/land cover (LULC), runoff depth, and proximity to roads were reclassified and weighted according to their importance for sand dam feasibility. Runoff depths ranged from 682-934 mm, with 69% of the basin receiving 820-930 mm, indicating abundant water availability. Slope analysis showed that 47.4% of the land has gentle gradients (0–5.23°), suitable for dam stability. However, limited feasibility was observed due to stream networks, with only 4.78% of the basin being moderately or highly suitable. Soil assessment identified Fluvisols (21.91%) and Regosols (2.5%) as ideal, whereas Leptosols (43.06%) were unsuitable. LULC mapping revealed that rangelands dominate (71.6%) and provide moderate suitability, while water bodies and flooded vegetation (~2.3%) are highly favorable. Areas more than 4,000 meters from roads (79.6%) were considered optimal to reduce flooding risks near infrastructure. Overall, the integrated analysis found only 1.2% (36,855 ha) of the basin as highly suitable and 10.96% as moderately suitable for sand dam construction, while 47.74% was unsuitable. Results show limited ideal sites and stress the need for localized assessments to ensure sustainable sand dam development.