Automatic extraction of boundary and channel network of mountainous watershed

Digital elevation model was created for the mountainous region located between the cities of Makkah AlMukaramah and Taif. The GIS software Idrisi was utilized to create the DEM of the region through digitizing contour lines of topographic maps of the region and interpolating the elevation over the surface. The Watershed Management System software was then used to automatically extracting the boundary and the channel network of Wadi Namman watershed from the created DEM. Both boundary and channel network of the wadi were extracted manually from topographic maps of the region. Then, automatically and manually extracted boundary and network were compared. The automatic procedure produced reasonable estimate of drainage basin characteristics. The automatic procedure was recommended since it is faster, has less error due to human mistakes and cost less whenever the digital map of the studied region is available.