Abstract
The groundwater resource in the Kingdom of Saudi Arabia is a non-renewable resource. Geographical information system and remote sensing are proven to be an efficient tool for locating water harvesting and recharge structures by prioritization of sub-watersheds through morphometric analysis. In this study, the watershed prioritization in Asir Province has been assessed by linear, aerial, and relief morphometric parameters. Morphometric analysis has been attempted to prioritize a total of eleven sub watersheds, of which six sub-watersheds in Tathlith Wadi and five sub-watersheds in Bisha Wadi were delineated using digital elevation model (DEM). Advanced space-borne thermal emission and reflection radiometer of 30m resolution DEM has used to generate drainage networks and delineation of sub watersheds using ArcGIS software. The important derived morphometric parameters have computed on the base of already developed mathematical formulae and methods. A novel and quantitative approach based on the compound parameter by using linear and shape parameters of the respective sub-watershed was attempted for its prioritization. The total area of sub-watershed in Wadi Bisha, which lies under high, medium, and low priority is approximately 40%, 20% and 40% respectively. whereas in Wadi Tathlith, the area under high and medium priority is 67% and 33%. The watersheds BSW2 and BSW4 in Wadi Bisha and TSW1, TSW2, TSW3, and TSW5 in Wadi Tathlith would require immediate intervention and efficient action plan for water and soil conservation. The interrelationship between the various morphometric factors of the basin has been studied using a correlation matrix. Further, morphometric factors have been studied in relation to the sub-basins to understand the existing relation between the factors and the sub-basins. The prioritized watersheds were validated using the water yield data from borewells in the respective watersheds. All high prioritized watersheds but one in Wadi Tathlith (TSW3) showed poor water yield. Prioritized sub-watersheds require immediate soil & water conservation initiative according to the given rank to ensure efficient watershed planning and management and improving the potential of water resources under sustainable watershed management and development in the Asir province of the Kingdom of Saudi Arabia.