Calculation of the vegetation index (NDVI) in the Oued Dades watershedusing Landsat 8 OLI satellite imagery (The southern edge of the Central High Atlas)

Abstract

Remote sensing and geographic information system (GIS) techniques will be used to conduct a study of the vegetation index, erosion rate and solid load migration in the Oued Dadès watershed. It is located on the southern slopes of the central High Atlas, on the northern front of the eastern Anti-Atlas (Sagro massif). This study calculates the vegetation cover index (NDVI) on the basis of Landsat Oli8 satellite images, and extracts maps of slope and hydrographic network intensity using the digital terrain module (DTM). All these parameters suggest that the study area is sparsely vegetated, with the exception of some farmland along the banks of Oued Dadès. Slope maps show that steep slopes are concentrated to thenorth, representing the upper reaches of the Dades valley, and that their importance diminishes further downstream. The distribution of the canal network is higher in the upper parts of the valleys and gorges, and ranges from 1 to 5. As precipitation often occurs in these areas in the form of thunderstorms, the interaction of all these parameters results in high levels of erosion and displacement of solid loads. In addition to lithological properties, which play a very important role in vegetation development and slope stability, they also contribute to the reduction of the solid load.