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The Gulf of Guinea's low-lying soft coastline is highly vulnerable to coastal erosion and relative sea-level rise (rSLR). Large capital cities and core economic activities are concentrated along the coastline, and potentially exposed to unforeseen risk. Currently, there is limited research on the impacts and vulnerability to rSLR (i.e. including land subsidence). Recent advances in satellite derived global digital elevation model (DEM) data offers exciting opportunities to assess coastal elevation at large scale and identify “hotspots” of potential sea-level rise vulnerability. Hereto, this study presents first a literature review on coastal vulnerability to rSLR in the Gulf of Guinea region. Secondly, this study use recent global satellite based DEMs for a coastal elevation assessment of the Gulf of Guinea to identify low-lying geographical areas needing more detailed investigations. Findings from satellite remote sensing are validated with in-situ data points in the Volta Delta. The results from the literature review highlights that very few publications investigate the combined effects from global SLR and land subsidence in the studied area. None investigates the drivers of land subsidence. Our analysis on satellite-based DEMs shows that there are large uncertainties on coastal elevation in the area, with considerable discrepancies between DEMs (>1m). These results highlight the importance of validation, either through ground-truthing or advanced approaches such as incorporating multiple DEMs. Unfortunately, field data that can be used as reference are scarce in the region, emphasizing the need for more field measurements and publicly available data. Incorporating newer data – e.g. LiDAR or high resolution optical stereo grammetry – is expected to improve assessments significantly and should be further explored. Based on the combination of FABDEM and CoastalDEM_v2.1, several coastal hotspots of vulnerability to SLR have been identified, including Lagos, Niger Delta, Cotonou, Western Accra, the Volta region, and urban areas surrounding the Ebrie lagoon within Abidjan. We conclude our study with concrete suggestions for future research and projects on rSLR in the region. 

pdf : 3.51 MB
author(s) :
Roberta BONI
Marie-Noëlle WOILLEZ
Rafael ALMAR
Selasi Yao AVORNYO
coordinator :
collection :
Research Papers
issn :
2492 - 2846
pages :
number :
available also in : en
3.51 MB (pdf)
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