Temporal (1948–2012) and Dynamic Evolution of the Wouri Estuary Coastline within the Gulf of Guinea

Abstract

The Wouri estuary is located in the Gulf of Guinea on the Atlantic coast of Cameroon’s coastline plain (3°49′ and 4°04′ north latitude and 9°20′ to 9°40′ east longitude), and is strongly influenced by coastal dynamics that have remained unquantified over a long period of time. This study analyzed the historical evolution of the Wouri estuarine coastline between 1948 and 2012. Variations in the estuarine evolution of the Wouri were studied from (i) minute topographic extracts from 1948, (ii) 1996–1999 nautical charts, and (iii) 2012 spatial map vectors. The net temporal spatial variation rates were calculated using the statistical methods of the Digital Shoreline Analysis System (DSAS). These change rates were also calculated over two time intervals (1948–1996 and 1996–2012) and over a 64-year period (1948–2012). The study reveals highly disparate results. Indeed, kinematics show that the Wouri estuary was dominated by erosion in its downstream section, with 262.83 ha for –3.2 m/year and 110.56 ha for –5.8 m/year between 1948–1996 and 1996–2012 respectively, and by accretion on the other hand in its upstream section, with 239.17 ha for 4.3 m/year in zone 5 between 1948–1996 and 150.82 ha for 12.6 m/year in zone 4 between 1996–2012. Thus, over the 64-year period (1948–2012), we have a dominance of variation by erosion downstream and conversely by accretion upstream, marked by the presence of amplifying factors (anthropogenic pressure and climate change) of the rate of variation of morphological evolution at the beginning of the 21st century, as compared to the middle-20th century. The observed development of sediment loss and accumulation, both influences and will influence, the sediment regime along the Wouri estuarine coastline. There is a need to develop a systematic sub-regional coastal surveillance activity to effectively manage Cameroon’s coastline system.

The Salient Dynamics of Cross-Border Ocean Governance in a Regional Setting: An Evaluation of Ocean Governance Systems and Institutional Frameworks in the Guinea Current Large Marine Ecosystem

“…Illegal and legal sand mining occurs in Cameroon, particularly around coastal cities and towns where industrial activity and construction are high, e.g., port development, land reclamation and housing construction, etc. (Asangwe, 2006;MINEP, 2011;Fotsi et al, 2019). All these puts together have exacerbated coastal erosion, habitat degradation and loss of livelihood (UNESCO/IOC, 2020b).…”

Quantifying Coastal Shoreline Erosion Due to Climatic Extremes Using Remote-Sensed Estimates from Sentinel-2A Data

“…All the geo-referencing of the satellite images was done in the WGS84/UTM Zone 40 projection system in GIS 10.8 software. Projecting the data on WGS84 in the Equatorial Mercator Projection (UTM) was used to achieve an accuracy of less than 20 m in absolute planimetric (Fossi Fotsi et al 2019). This study used the screen digitization technique to delineate the shoreline data obtained from the satellites using ArcGIS 10.8 software.…”

“…To optimize the model output, it is important to evaluate the errors associated with shoreline extraction from satellite imagery. This study adopted Fossi Fotsi et al (2019) approach in measuring the uncertainty in coastal extraction with some modifications, and the annualized error was calculated (Table 2).…”

Long-Term Analysis of Wave Climate and Shoreline Change along the Gulf of California

“…In addition, it is estimated that 24 to 70% of the sandy beaches around the world are being eroded [5][6][7], and considering the projected variations in sea levels and wave energy, the erosion rates and the percentage of threatened sandy beaches are likely to increase. This highlights the relevance of integrating the effects of CC into coastal impact assessments, in order to generate more accurate adaptation plans.…”