Spatio-temporal variations of future wave climate-driven longshore sediment transport in the Gulf of Guinea

• Published in: Coastal engineering journal Vol. 66; no. 2; pp. 234 - 269
• Main Authors: Dahunsi, Adeola M., Dada, Olusegun A., Bonou, Frederic, Baloïtcha, Ezinvi
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Inc 02.04.2024
• Subjects: Breakers; Climate change; Computation; Deep water; Empirical analysis; Longshore sediment transport; Population density; Seasonal variation; Seasonal variations; Sediment; Sediment transport; Significant wave height; Soil erosion; Surf zone; Temporal variations; Wave climate; Wave direction; Wave energy; Wave height; Wave period; Wave power; Gulf of Guinea
• ISSN: 2166-4250; 1793-6292
• DOI: 10.1080/21664250.2023.2290316

The densely populated coast of the Gulf of Guinea (GoG) is experiencing escalating erosion from climate change (CC). To assess Longshore Sediment Transport (LST) changes in the past and future, an empirical formula was used to model the GoG’s LST. Nearshore wave conditions, crucial for LST estimation, were derived by projecting significant wave height, mean wave period, and mean wave direction from deep water to the breaker zone. These wave conditions were used as input for LST computation. Analysing three time slices: Past (1979–2005), mid-century (2026–2045), and end-century (2081–2100) under RCPs 4.5 and 8.5, results indicate continuous increase in LST in most locations, with local and seasonal variations. LST magnitudes range from 104 to 105 m3y−1 in the GoG, with the Cameroonian coast having the least. This aligns with the rising wave energy from CC. LST directions are predominantly eastward, though some locations, like off Lagos and Cameroon-Gabon coasts, show westward trend, correlating with coastal orientation influenced by southward wave directions. RCP 8.5 projections suggest mid-century increase, intensifying by end of century, with yearly rates of change around 103 m3y−1 and future LST changes up to 105 m3y−1. This situation implies accelerated sediment removal, heightening erosion.