Periodical Morphodynamic Changes of Sand Movements at El Jadida Beach

Abstract

El Jadida Beach (X: -8.5007116; Y: 33.2316326) is a sandy beach of low altitude that constitutes a kind of enclave located between the port of El Jadida and rocky outcrops. It is influenced by natural and anthropic factors, as well as the impact of tourism, particularly during the summer, when sand is used for amusement activities (Beach Ball competition). In order to follow the morphodynamic changes of this beach, we carried out a study on two different time scales: a fifty-five years (1963 – 2018) shoreline evolution study using aerial photos and satellite images based on GIS tools using the Digital Shoreline Analysis System (DSAS) and a two-years (2017 – 2019) morphological beach study using a Differential Global Positioning System (DGPS). According to the results obtained by the diachronic study, the beach studied showed erosion in its middle and an accumulation at these bulges. This result is due to the presence of the harbor breakwater to the NW and the rocky outcrops to the SE; acting as a barrier preventing the movement of sediments and the erosion in the middle can be explained by the reduction of the sediment supply from the Oued Oum Erabia and by the exposure of this part to the dominant swells and also the human activities like used the beach for amusement activities (Beach Ball competition and other). Beach profile observations results show accumulation in the subaerial beach and erosion in the lower part of the foreshore. The study on two different time scales adopted in this paper, allowed us to understand longshore and cross-shore sedimentary mobility.

Keywords

• gis tools
• dsas
• sandy beach
• dgps
• longshore drift
• cross-shore