Morphometric Assessment of Two Watersheds of High Atlas of Morocco Using Remote Sensing and GIS Techniques: What Is the Impact on Surface Water Availability?

Abstract

The abundance or scarcity of surface water in a watershed is related to environmental factors including its morphology, substrate type, rainfall, slope, and exposure to moist air masses. The combination of these characteristics explains the hydrological behavior of the river network, knowledge of which is important for water resources management. Geographic Information System and Remote Sensing are efficient tools to assess the morphometric characteristic in a watershed. Using these tools, the physical characterization of the two water basins located on either side of the High Atlas of Morocco was investigated in this study. The results show that the Upper Draa basin is characterized by an elongated shape, with a drainage density of 0.14 km/km 2 . Altitudes and slopes vary little and slopes are oriented in most cases towards the southeast (27.34%). Substrate is mostly permeable, which promotes infiltration and aridity of the soil. This contrasts with the Zat basin that is characterized by very variable elevations and slopes, and slopes are mainly exposed to the North and North-West (30.42%), which therefore favors strong runoff and a very high flow velocity. The hydrological contrast observed in the two basins impacts the human use of surface water. These results effectively ex-plain the hydrological behavior and provide managers with useful information for better management and decision-making regarding the two studied hydro systems.