Contribution of GIS and remote sensing to study and analyze the physiographic characteristics of the oued el-abid watershed (Central High Atlas, Morocco)

Abstract

The present research describes the contribution of geomatic science in extracting, analyzing, mapping and determining the physiographic characteristics of the watershed of Oued El-Abid located in Central High Atlas, Morocco, which covers an area of 6405 km 2 and a perimeter of 527 km. The methodology adopted in this work is based on the use of digital terrain model (DTM) from SRTM images of 30*30 m resolution to identify and characterize the watershed and a Landsat 8 satellite image taken in August 2019, which leads us to calculate the physiographic and geometric characteristics of the watershed such as its shape, relief, geology, land use and hydrographic network. The results obtained show that the basin has an elongated shape with a moderate relief. The hypsometric view reveals that high altitude zones (1563 to 2763 m) are mainly distributed in the center and the southeast of the basin and the low altitudes are located in the west of the basin. This distribution of altitudes is related to the topography of the watershed. The hydrological view shows that the hydrographic network has a medium hierarchy while the typological aspect of the main river is about 6 (Lc= 203.17 Km). Also, the geological analysis reveals that the basin is mainly constituted by the Dogger and Lias terrains represented by limestone and marl formations, and the Cretaceous terrains represented by marl, marl and sandstone formations. The lithological nature of the basin is marked by permeable rocks (56%) constituted essentially by the carbonated, karstified and fractured mass.