Drainage Network Simulation Case Study: Wadi Dhara Abdullah S. Al-Wagdani & Samaeer M. Bamufleh Department of Hydrology, Faculty of Meteorology, KAAU, P.O. Box 80208, Jeddah 21589, Saudi Arabia ABSTRACT: Digital elevation model was created for Wadi Dhara which is an upstream mountainous catchment of Aleeth basin. The study region is located in southwestern part of Saudi Arabia. The GIS software Idrisi was utilized to create the DEM of the region through digitizing 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 Dhara watershed that is located in the studied region from the created DEM. Both boundary and channel network of the wadi were extracted manually from topographic maps of the region. The automatically and manually extracted boundary and network were compared. The results of the two techniques were found very similar in terms of area and shape of the channels. 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.