Abstract
The world today faces water scarcity issues, especially in developing countries. This situation is further aggravated under arid and semiarid climates with the water demand increasing and limited rainfall events. The study was conducted in the Riyadh metropolitan area of Saudi Arabia. The study area has a hot arid desert climate. Therefore, there is an urgent need for harvesting rainwater to confront the increasing water demand. This research aims to identify the potential rainwater harvesting (PRWH) suitable sites based on the multi-criteria decision support system by the spatial analytic hierarchy process, with the aid of the integration of geographic information systems and remote sensing techniques. Mapping PRWH was carried out using the thematic layers of the slope, soil texture, land use and land cover (LULC), precipitation, and potential runoff coefficient (PRC). The study findings revealed that Riyadh has four hydrologic soil groups (HSGs), namely A, B, C, and D groups, and the percentage area is 2%, 26%, 3%, and 71%, respectively. The slope classes are flat (< 2%), sloping (2-8%), strongly sloping (> 8-15%), moderately steep (> 15-30%), and mountainous (> 30%). The LULC layers are barren lands, agricultural lands, urban, and roads. The precipitation has been distributed into five classes namely very low (5.9%), low (10.1%), medium (13.2%), high (13.5%), and very high (57.3%) of the total investigated area. The PRC values were distributed in five levels namely very low (< 0.2), low (0.2-0.3), medium (> 0.3-0.5), high (> 0.5-0.7), and very high (> 0.7-1), where about 83% of the capital faces high and very high PRC values. The percentage area of PRWH suitability sites is unsuitable (0.4%), poor (0.8%), moderate (13.3%), good (47.5%), and excellent (38%) of the total entire area. More than 85% of Riyadh has good and excellent suitability for PRWH. This study is tantamount to a powerful tool for identifying the PRWH suitability sites in arid and semiarid regions to confront the water demand increase.