Physical Forcing Induced Coastal Vulnerability along the Gulf of Guinea

Angora Aman,René A Tano,Foungnigué Silué,Kwasi Appeaning Addo,Elisée Toualy,Regina Folorunsho

doi:10.4236/jep.2019.109071

Abstract

Coastal areas of the Gulf of Guinea experience accelerated degradation as a result of erosion and flooding associated with intensification of extreme marine-meteorological phenomena. The coastal erosion process, especially on the sandy or muddy littoral, constitutes one of the main factors of the degradation of the Gulf of the Guinean coast. These risks, which are still poorly studied, could increase over the coming decades because of climate change and the human activities that exacerbate them. Data related to ocean forcing (tide, wave, and sea level anomaly), to hydrologic parameter (rainfall) and to the state (geomorphology, coastal slope, and rate of coastal retreat) of the coast were analyzed by several statistical methods and a numerical vulnerability model to map the vulnerability of the different coastlines of this region. The results showed that the vulnerability of these coastal areas is influenced by geomorphology, tide, waves and rainfall intensity. 24.34% and 37% of the entire coast are of low and moderate vulnerability respectively. While 26.98% and 11.66% are of high and very high vulnerability respectively. This information could facilitate developing sustainable policies to effectively manage hazards in this coastal zone.

Highlights

The coastline is dynamic and is, an area of constant change
Data related to ocean forcing, to hydrologic parameter and to the state of the coast were analyzed by several statistical methods and a numerical vulnerability model to map the vulnerability of the different coastlines of this region
The secular trend is 3 mm/yr along the coastal area from Cote d’Ivoire to Nigeria. This result and those obtained by [11] [39] and [40], are close. This upward trend in sea-level along these coastal areas is a strong threat for coastal communities, ecosystem, infrastructures and coastal tourism through coastal erosion and temporal or permanent inundation induced by this natural forcing

Summary

Introduction

Coastline changes induced by erosion and accretion are natural processes that take place over a range of time scales. They may occur in response to smaller-scale (short-term) events, such as storms, regular wave action, tides, and winds, or in response to large-scale (long-term) events such as sea levels (rise/fall) and coastal land subsidence or emergence [4] [5]. An imbalance between sediment supply and demand may lead to the erosion of coastal sections that were historically stable

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