Abstract

This study aimed to build a database of the morphometric characteristics of the Wadi Rafad watershed (Shabwah Governorate, Yemen) by analyzing a Digital Elevation Model (DEM) with a spatial resolution of 10 m. The analysis was conducted using WMS 10 and ArcGIS 10.3 software, with the assistance of Global Mapper 13, in addition to a set of topographic and geological maps and satellite imagery of the watershed. The aim was to obtain the watershed's morphometric characteristics, including its spatial, morphological, topographic, and drainage network characteristics, to provide a digital database for future use. A descriptive approach was used to describe and analyze the watershed natural characteristics, while a quantitative approach was employed for spatial data analysis and producing digital maps. This involved calculating variables and morphometric characteristics and interpreting the results. Digital maps were produced showing elevations, slopes, rock units, and the tributary network. The topographical characteristics varied due to variations in their formation and development processes, as well as the different geological factors that formed them, particularly the lithological nature, geological structures, topographic features, and climate conditions. The watershed elevation ranges between 15 and 1679 m and slope of 0.21. Its covers an area of 650.6 km² with a length, width and perimeter of 38.9 km, 16.7 km and 153.3 km, respectively. Shape factor, circularity and Elongation ratio is 0.43, 0.35 and 0.74, respectively which indicates fine texture, elongated watershed shape and natural flood-lowering potential. The watershed has a drainage network of 7th order with an average drainage density of 2.92 km/km2, stream frequency of 9.9 /km2 and the dominate drainage pattern is dendritic. It is currently in a state of equilibrium. We recommend using a high spatial resolution DEMs to study its morphometric characteristics, which can be used for watershed management and other hydrological studies in future.