Fluvial Dynamic in Oued El Abid Basin: Monitoring and Quantification at an Upstream River Section in Bin El Ouidane Dam - 2016 / 2017-(Central High Atlas / Morocco)

Abstract

Soil erosion is a complex phenomenon, which particularly influences water and soil potentials. In the mountainous areas, water erosion phenomenon is accentuated by steep slopes and the degradation of vegetation cover. soil erosion is a worldwide phenomenon threatening the social, environmental and the economic life. In Morocco, fluvial erosion is one of the issues that affects the national territory. The location of Morocco, in the south of Mediterranean region provides remarkable climatic and ecological diversity. Located in the Moroccan High Atlas, El Abid basin belongs to a semi-arid climate. It is characterized by steep slopes and abundant precipitation which gives mountain flows a torrential characteristic. The discharge can reach very important values. Long term hydrological records for El Abid river (1970–2017) demonstrate the annual and seasonal variability in discharge with winter and spring periods typically representing 87% of the flow. Soils are increasingly degraded and sediments from erosion contribute to the siltation of Bin Ouidane dam. This siltation is the result of deposits of soil erosion. During flood periods this dam is silted by the sediment transport. This article aims to quantify the rate of fluvial erosion in the upstream section of the Bin El Ouidane dam. Then, to understand the process of river dynamics and its impact on silting issue, through the application of an approach technique based on the realization of several cross profiles, and with a main objective being to compare the results of the river dynamics of the two campaigns during 2016 and 2017. In addition, the measurements taken were supplemented by qualitative observations, particularly during the baseflow of the river, the incision of the bed (or stream), the regressive erosion of the banks, the apparent nature of the substrate, and certain anthropogenic actions.