Hydrogeomorphological dynamics and erosion of the soft coasts in tropical Africa, the case study of the Wouri estuary, Cameroon
Abstract Coastal erosion poses a significant challenge along Africa’s Atlantic coast, with flooding ranking as the second most pressing threat after erosion. This issue is particularly acute in Cameroon, especially along the Kribian coast and the Wouri estuary, where Cape Cameroon is undergoing seve...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Springer
2025-05-01
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| Series: | Discover Geoscience |
| Subjects: | |
| Online Access: | https://doi.org/10.1007/s44288-025-00154-1 |
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| Summary: | Abstract Coastal erosion poses a significant challenge along Africa’s Atlantic coast, with flooding ranking as the second most pressing threat after erosion. This issue is particularly acute in Cameroon, especially along the Kribian coast and the Wouri estuary, where Cape Cameroon is undergoing severe erosional processes. The central research question of this study examines whether the erosion in the Wouri estuary is due to local factors or part of a broader dynamic affecting the entire Atlantic African shoreline. The study aims to achieve three main objectives: (i) to map shoreline dynamics in the Wouri estuary from 1975 to 2019, identifying and quantifying eroding segments; (ii) to analyze factors contributing to erosion in the Wouri estuary and those common to other Atlantic African coasts; and (iii) to contextualize these findings within current scientific literature. Utilizing Hilhorst’s theory of “reciprocity” or “complexity”, the study recognizes that coastal areas are shaped by both physical and human factors influencing natural hazards like erosion and flooding. To investigate the causes of coastal erosion, a smaller-scale map (1:5000) derived from Landsat images (30-m resolution) and a larger-scale map (1:1500) based on Pleiades and Google Earth images (0.5-m resolution) were employed, focusing on Cape Cameroon. The imagery covers various years: Landsat (1975, 1986, 2000, 2016, 2024), Pleiades (2013, 2018), and Google Earth (2000, 2016). Shoreline extraction utilized both automatic (unsupervised classification) and semi-automatic (digitization) methods, especially in cloud-obscured areas. The Digital Shoreline Analysis System (DSAS) within ArcGIS 10.7.1 quantified shoreline retreat rates using the End Point Rate (EPR) method while meticulously calculating sources of error and uncertainty. Analysis of Landsat imagery revealed that over 75% of the Wouri estuary’s shoreline is eroding, with average retreat rates ranging from − 3 m/year to − 11 m/year between 1975 and 2020. Hotspots for erosion include Cape Cameroon, the coastal spit around Manoka Island, and the vicinity of the APD. The northern tip of Cape Cameroon retreats at an estimated rate of − 15 m/year, with a maximum retreat at 53 m. Conversely, an annual accretion rate of + 5 m/year was noted at Toubé from 1975 to 2024. These findings highlight the dynamic nature of the coastal region, which may reflect broader trends across West African coasts experiencing intense erosion. This study lays a foundation for comprehensive coastal research and management, providing insights applicable to other African coastlines to mitigate the impacts of coastal erosion. |
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| ISSN: | 2948-1589 |