For better watershed control, protection, water resource planning and seabed development; it is important to aquire master the its physical environment. The aim of this study is to understand the hydrological functioning of the watershed through its physical environment in order to successfully manage it. The data from the 30 m resolution Shuttle Radar Topographic Mission (SRTM) and the 1/200,000 scale urban mapping of the study area were used. The description of the watershed showed that it is an elongated and covers an area of 498.78 km2. It is characterized by an old relief with a very low slope with an average drainage density of about 0.67 km/km2. The shallows cover an area of 1981 ha. This study shows the sensibility of the catchment to run-off and consequently to develop it in order to ensure its sustainable exploitation.