Vulnerability of coastal cities and mangroves to the combined effects of Land subsidence, relative sea-level rise, and groundwater extraction along the low-lying coastland of Cameroon

The coast of Cameroon, which is approximately 590 km in length, is situated in the Gulf of Guinea and is characterized by its low elevation above sea level and sedimentary geology, making it particularly susceptible to erosion, subsidence, and sea level rise. The coast of Cameroon and its extensive mangrove forests are facing numerous economic pressures, including encroachment from urban expansion, agro-industrial development, port activities, oil and gas exploration and exploitation, and the increased pollution associated with these activities. Additionally, many rapidly growing cities located along the coast (Douala, Kribi, Tiko, Limbe) and neighbouring the mangroves (Duala estuary, Rio Del Rey estuary, and Ntem estuary) are currently experiencing alarming rates of coastal erosion, frequent flooding, complete loss of land, and evidence of subsidence from regional and continental research. Unfortunately, there have been no detailed investigations of the combined effects of land subsidence and sea-level rise, known as relative sea-level rise, and their present and future impacts on Cameroon's emerging coastal cities and mangroves under climate change. Therefore, this research aims to fill this knowledge gap by investigating, understanding, and projecting the causes, consequences, and coastal vulnerability related to land subsidence and sea-level rise to enable the development of information-based mitigation strategies and policies. We will use remote sensing data, InSAR analysis, hydrogeological investigations, and modelling tools to assess the real coastal elevation of Cameroon, determine the actual land subsidence rate, determine the actual local relative sea-level rise from tide gauge data, determine the factors influencing land subsidence, project future elevation evolution, and establish an integrated vulnerability assessment of the coastal areas of Cameroon. This research will contribute to a proper understanding of Cameroon's mangrove landscape dynamics, the vulnerability of coastal infrastructure, and its biodiversity to relative sea-level rise, subsidence, coastal retreat, and future flooding events. The outcome can be used to develop sustainable management strategies for Cameroon's coastal zone.