Morphodynamics and Evolution of Estuarine Sandspits along the Bight of Benin Coast, West Africa

Abstract

It is well known that estuarine systems are significantly affected by hydrodynamic conditions such as river discharge, storm surges, waves and tidal conditions. In addition to this, human interferences through developmental projects have the capability of disrupting the natural morphological processes occurring at estuaries. In West Africa, the goal to improve standards of living through large-scale dam construction, offshore ports and coastal erosion countermeasures has triggered alarming changes in the morphodynamics of estuarine systems. The estuaries at the Volta River mouth (Ghana) and “Bouche du Roi” inlet (Benin), located along the Bight of Benin coast, West Africa, were selected as two case study sites to examine their long-term morphodynamics and sandspit evolution. In this study, we primarily analyzed estuarine morphology using remotely sensed images acquired from 1984 to 2020. We further estimated the longshore sediment transport for this region using results from the image analysis and the depth of active sediment motion. Our results reveal that the longshore sediment transport rates for this region are in the magnitude of 105–106 m3/year. Comparative analysis with other estuaries and sandy coasts suggests that the longshore sediment transport along this coast has one of the largest rates estimated in the world.

Keywords

• estuarine systems
• river mouth
• tidal inlet
• longshore sediment transport
• morphodynamics
• satellite image analysis