Strategic dam site selection and hazard mapping using remote sensing: insights from Wadi Araba, Egypt

Abstract

Flash floods represent one of the most recurrent and devastating geohazards affecting Egypt’s northern area of the Red Sea coast, particularly in hyper-arid catchments such as Wadi Araba. This study develops a geospatial decision-support framework to identify flash-flood-prone areas and determine optimal dam locations for flood mitigation and groundwater recharge. The analysis incorporates eight thematic layers: slope, LULC, rainfall, DEM, drainage density, lineament density, distance to main streams and roads. The data used for thematic layers was derived from satellite imagery and ancillary datasets, processed using remote sensing and GIS tools. A multi-criteria decision analysis (AHP) generated a weighted overlay model of flood susceptibility. The resulting map classified Wadi Araba into high-risk (0.53 km²), moderate-risk (2354.8 km²), and low-risk (1671.34 km²) zones, with the highest risk concentrated in the southern Galala Plateau, moderate-risk zones occurring in lowland and downstream basins, and low-risk zones mainly located in the northern Galala Plateau and western Wadi Araba. The RS–GIS/AHP framework identified top-ranked dam sites with favourable storage geometry; validation returned medium AUC for susceptibility of flash flooding (≈ 0.6–0.7) and good AUC for dam suitability (≈ 0.7–0.8).