Assessment Of Land Use Dynamics Effect On Water Erosion : Case Of The Bouregreg Sub-Watershed Upstream Of The Tiddas Dam.

This paper aims to assess the impact of land-use evolution on water erosion in the Bouregreg subwatershed upstream of the Tiddas dam in the central Moroccan plateau. The methodology adopted is based on a diachronic study of land use between 1989 and 2019 from Landsat images of 30 m resolution. After the necessary pre-proc8essing, a classification of the images of the area using the Support Vector Machine (SVM) algorithm was performed and validated via the data from the processing of aerial photographs from 1989, Google Earth satellite images at a high resolution from 2019 and field validation outputs. The predictive approach falling under the guidelines for mapping and measuring water erosion processes has been exploited to assess the evolution of potential areas for erosion (PAP/CAR guidelines). The results highlight the forest’s regression of 5% during the 30 years and the increase in the stages of degradation, namely the rangeland of 6%. The level of erodibility occupying the subwatershed is high to extreme, totalling 63% of the total area. The high to very high levels of soil protection have experienced a regression in their areas ranging from 30% in 1989 to 18% in 2019. The areas vulnerable to a very high level of erosion have seen an increase from 21% in 1989 to 38% in 2019. These results clearly show the worrying state of the area's vulnerability, and thus, make it possible to provide decision-makers with scientific elements that can guide the planning and implementation of action programmes for the protection of the Tiddas Dam.