Sand dam suitability assessment using integrated geospatial and multicriteria decision analysis to strengthen water security in arid and semi-arid regions: a case of the Lower Awash basin, Ethiopia

Abstract

ABSTRACT Lower Awash Basin an arid environment where water availability is highly uneven across locations and seasons, while demand for domestic supply, agriculture, and development is steadily increasing. Sand dams have strong potential to enhance local water storage and improve access, but their success depends not only on runoff volume. They also require suitable stream channels, gentle slopes, favorable soils, appropriate land cover, and accessible terrain, conditions that occur only in limited parts of the basin. This study mapped and ranked potential sand dam sites using geospatial techniques integrated with multicriteria evaluation and the analytic hierarchy process. Six biophysical criteria were assessed, and slope and stream order emerged as the most influential factors, together contributing 76% of the total suitability weight. Although about 69% of the basin has runoff potential in the range of 820–930 mm, only 1.2% (36,855 ha) satisfies the combined requirements for high suitability. Fluvisols and Regosols were generally favorable, whereas Leptosols, covering 43% of the basin, restrict drainage and storage potential over wide areas. The findings show that apparent runoff potential does not automatically translate into suitable sand dam sites, highlighting the need to focus investment on a small number of highly suitable clusters.