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

ABSTRACT

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.

KEYWORDS:

• Gulf of Guinea
• longshore sediment transport
• empirical modelling
• wave climate
• climate change
• ensemble

Acknowledgments

This study is performed as part of the DAAD In-Country/In-Region Scholarship Programme for Sub-Saharan Africa at the University of Abomey-Calavi, International Chair in Mathematical Physics and Applications (ICPMA-UNESCO Chair) in Benin Republic. The authors acknowledge the magnanimity of the working group of the Coordinated Ocean Wave Climate Project Phase 2 project (COWCLIP) (https://cowclip.org/- Accessed: 2022-07-20) for making the data publicly available for use.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

A.M.D: Conceptualization; Data Curation; Methodology; Validation; Visualization; Writing-Original Draft; Writing-Review & Editing.

O.A.D: Conceptualization; Methodology; Supervision; Writing-Reviewing & Edit-ing.

F.B: Data Curation; Methodology; Software; Validation; Supervision; Writing- Re-viewing & Editing.

E.B: Resources; Project Administration; Supervision.

Data availability statement

The Coordinated Ocean Wave Climate Project phase 2.0

(COWCLIP2.0) wave climate database used in this study is publicly available at

https://cowclip.org/data-access/ (Accessed: July 20 2022).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/21664250.2023.2290316

Additional information

Funding

This research received no external funding.