Multidecadal evolution of the shoreline change at Agadir beach (Morocco): A GIS and high-resolution satellite imagery analysis

Abstract

Beaches are extremely fragile and dynamic natural environments, where waves, coastal currents, and winds perpetually deposit and move sediments. The evolution of these beaches can only be envisaged by monitoring coastline dynamics at different spatiotemporal scales. In recent years, the use of high-resolution satellite images and GIS has become an indispensable tool for assessing beach evolutionary trends. In this contribution, we emphasize the importance of these new technologies for monitoring shoreline evolution on highly anthropized beaches, focusing on the case of Agadir beach on Morocco's Atlantic coast. A diachronic analysis of shoreline evolution was carried out over a period of 55 years extending from 1968 to 2023. This analysis is based on both high-resolution satellite images from various sensors (Corona, OrbView-3, Pleiades, WorldView-2) and the DSAS (Digital Shoreline Analysis System) tool integrated into ArcGIS©. The results obtained show a contrasting evolution, with a general trend towards erosion in the center and south of the beach, and an accentuated beach nourishment to the north. This trend is mainly attributed to the construction of a port complex (commercial harbour, fishing port, and marina) and to the various coastal developments undertaken on the beach.