JEP  Vol.10 No.9 , September 2019
Physical Forcing Induced Coastal Vulnerability along the Gulf of Guinea
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.
Cite this paper: Aman, A. , Tano, R. , Toualy, E. , Silué, F. , Addo, K. and Folorunsho, R. (2019) Physical Forcing Induced Coastal Vulnerability along the Gulf of Guinea. Journal of Environmental Protection, 10, 1194-1211. doi: 10.4236/jep.2019.109071.

[1]   Tano, R.A., Aman, A., Toualy, E., Kouadio, Y.K., Francois-Xavier, B.B.D. and Addo, K.A. (2018) Development of an Integrated Coastal Vulnerability Index for the Ivorian Coast in West Africa. Journal of Environmental Protection, 9, 1171-1184.

[2]   Boateng, I., Wiafe, G., and Jayson-Quashigah, P.-N. (2016) Mapping Vulnerability and Risk of Ghana’s Coastline to Sea Level Rise. Marine Geodesy, 40, 23-39.

[3]   WACOM (West African Coastal Observation Mission) (2011) Regional Study for Shoreline Monitoring and Drawing up a Management Scheme for the West African Coastal Area.

[4]   Prasetya, G.S. (2007) The Role of Coastal Forest and Trees in Combating Coastal Erosion. In: Braatz, S., Fortuna, S., Broadhead, J. and Leslie, R., Eds., Coastal Protection in the Aftermath of the Indian Ocean Tsunami: What Role for Forests and Trees, FAO, Bangkok, 25 P.

[5]   Gracia, F.J., Anfuso, G., Benavente, J., Del Río, L., Domínguez, L. and Martínez, J.A. (2005) Monitoring Coastal Erosion at Different Temporal Scales on Sandy Beaches: Application to the Spanish Gulf of Cadiz Coast. Journal of Coastal Research, Special Issue 49, 22-27.

[6]   WAMU (West African Economic and Monetary Union) (2010) West African Coastline Survey and Coastal Master Plan. 137.

[7]   WACA (West Africa Coastal Areas Management Program) (2016) A Partnership for Saving West Africa’s Coastal Areas. World Bank Group.

[8]   Giardino, A., Schrijvershof, R., Nederhoff, C.M., Vroeg, H.D., Brière, C., Tonnon, P.-K., Caires, S., Walstraa, D.J., Sosa, J., van Verseveld, W., Schellekens, J. and Sloff, C.J. (2018) A Quantitative Assessment of Human Interventions and Climate Change on the West African Sediment Budget. Ocean and Coastal Management, 156, 249-265.

[9]   Appeaning Addo, K. (2013) Assessing Coastal Vulnerability Index to Climate Change: The Case of Accra-Ghana. Journal of Coastal Research, Special Issue 65, 1892-1897.

[10]   Gornitz, V., White, T.W. and Cushman, R.M. (1991) Vulnerability of the US to Future Sea-Level Rise. In: Magoon, O.T., Ed., Proceedings of the Coastal Zone 91 Proceedings of the 7th Symposium on Coastal & Ocean Management, ASCE, Oak Ridge, 1345-1359.

[11]   Tano, R.A., Aman, A., Kouadio, K.Y., Toualy, E., Ali, K.E. and Assamoi, P. (2016) Assessment of the Ivorian Coastal Vulnerability. Journal of Coastal Research, 32, 1495- 1503.

[12]   Lamb, P. (1982) Persistance of Subsaharan Drought. Nature, 299, 46-47.

[13]   Mahé, C., Dessouassi, R., Cissoko, B. and Olivry, J.-C. (1998) Comparison of Interannual Fluctuations of Piezometry, Precipitation and Flow over the Bani-Douna Watershed. In: Servat, E., Hugues, D., Fritsch, J.M. and Hulme, M., Eds., Water Ressources Variability in Africa during the 20th Century, Proceedings de la conférence Abidjan 98, ORSTOM/AlSH/UNESCO, Pub. AlSH No. 252, 289-295.

[14]   Ibe, A.C. and Quelennec, R.E. (1989) Coastal Erosion Inventory and Control Methodology in the West and Central Africa Region. Regional Seas Reports and Studies, UNEP, Nairobi, 107 p.

[15]   Appeaning Addo, K. (2015) Vulnerability of Ghana’s Accra Coast to Sea Level Rise. Understanding Risk and Resilience in Complex Coastal Systems, 2nd Annual SURA Coastal Resilience Workshop, Fort Lauderdale, 26-28 October 2015, 15 p.

[16]   Blivi, A. (1993) Morphology and Current Dynamics of the Coast of Togo. Geo-Eco- Trop, 17, 25-39.

[17]   Houekpoheha, M.A., Kounouhewa, B.B., Hounsou, J.T., Tokpohozin, B.N. and Awanou, C.N. (2015) Statistical Analysis of Wave Heights on the Coast of Benin in the Gulf of Guinea: Energy Power of Non-Linear Swell in the Shoaling Zone. Revue des Energies Renouvelables, 18, 89-103.

[18]   Toualy, E., Aman, A., Koffi, P., Marin, F. and Wango, T.E. (2015) Ocean Swell Variability along the Northern Coast of the Gulf of Guinea. African Journal of Marine Science, 37, 353-361.

[19]   Degbe, C.G.E., Sohou, Z., Oyede, L.M., Adje, C., Du Penhoat, Y., Bourles, B., Chuchla, R. and Almar, R. (2017) Evolution of the Coastline of the Beninese Coast from 2011 to 2014. CAMES Journal, 5, 21-28.

[20]   Lemasson, L. and Rebert, J.-P. (1973) The Sea Currents in the Ivorian Gulf. Série Océanographie, 11, 67-95.

[21]   Morlière, A. and Rebert, J.P. (1972) Hydrological Study of the Ivorian Continental Shelf. Volume III, No. 2, Centre Rech. Océano, csUt, Abidjan, 1-30.

[22]   GCLME (Guinea Current Large Marine Ecosystem) (2006) Transboundary Diagnostic Analysis. 193 p.

[23]   Gornitz, V., Couch, S. and Hartig, E.K. (2002) Impacts of Sea Level Rise in the New York City Metropolitan Area. Global and Planetary Changes, 32, 61-88.

[24]   Nicholson, S.E., Kim, J. and Hoopingarner, J. (1988) Atlas of African Rainfall and Its Interannual Variability. Department of Meteorology, Florida State University, Tallahassee, 237 p.

[25]   Mann, H.B. (1945) Non-Parametric Tests against Trend. Econometrica, 13, 245-259.

[26]   Kendall, M.G. (1955) Rank Correlation Methods. Charles Griffin, 196 p.

[27]   Wang, X.L. and Swail, V.R. (2001) Changes of Extreme Wave Heights in Northern Hemisphere Oceans and Related Atmospheric Circulation Regimes. Journal of Climate, 14, 2204-2221.<2204:COEWHI>2.0.CO;2

[28]   Wang, X.L. and. Swail, V.R. (2002) Trends of Atlantic Wave Extremes as Simulated in a 40-Year Wave Hindcast Using Kinematically Reanalyzed Wind Fields.<1020:TOAWEA>2.0.CO;2

[29]   Sen, P.K. (1968) Estimates of the Regression Coefficient Based on Kendall’s Tau. Journal of the American Statistical Association, 63, 1379-1389.

[30]   Thieler, E.R. and Hammar-Klose, E.S. (2000) National Assessment of Coastal Vulnerability to Sea-Level Rise: Preliminary Results for the U.S. Gulf of Mexico Coast. U.S. Geological Survey, Woods Hole, Open-File Report 00-179.

[31]   McLaughlin, S., McKenna, J. and Cooper, J.A.G. (2002) Socio-Economic Data in Coastal Vulnerability Indices: Constraints and Opportunities. Journal of Coastal Research, Special Issue No. 36, 487-497.

[32]   Wu, S.Y., Yarnal, B. and Fischer, A. (2002) Vulnerability of Coastal Communities to Sea-Level Rise: A Case Study of Cape May County, New Jersey, USA. Climate Research, 22, 255-270.

[33]   Cutter, S.L., Boruff, B.J. and Shirley, W.L. (2003) Social Vulnerability to Environmental Hazards. Social Science Quarterly, 84, 242-261.

[34]   Chakraborty, J., Tobin, G.A. and Montz, B.E. (2005) Population Evacuation: Assessing Spatial Variability in Geophysical Risk and Social Vulnerability to Natural Hazards. Natural Hazards Review, 6, 23-33.

[35]   Li, K. and Li, G.S. (2011) Vulnerability Assessment of Storm Surges in the Coastal Area of Guangdong Province. Natural Hazards and Earth System Sciences, 11, 2003-2010.

[36]   Balica, S.F., Wright, N.G. and van Der Meulen, F. (2012) A Flood Vulnerability Index for Coastal Cities and Its Use in Assessing Climate Change Impacts. Natural Hazards, 64, 73-105.

[37]   Karymbalis, E., Chalkias, C., Chalkias, G., Gigoropoulou, E., Manthos, G. and Ferentinou, M. (2012) Assessment of the Sensitivity of the Southern Coast of the Gulf of Corinth (Peloponnese, Greece) to Sea-Level Rise. Central European Journal of Geosciences, 4, 561-577.

[38]   Boruff, B.J., Emrich, C. and Cutter, S.L. (2015) Erosion Hazard Vulnerability of US Coastal Counties. Journal of Coastal Research, 21, 932-942.

[39]   Woodworth, P.L., Foden, P., Pugh, J., Mathews, A., Aarup, T., Aman, A., Nkebi, E., Odametey, J., Facey, R., Abdulgafor, M.Y.E. and Ashrar, M. (2009) Insight into Long Term Sea Level Change Based on New Tide Gauge Installations at Takoradi, Aden and Karachi. International Hydrographic Review, 1, 18-22.

[40]   Evadzi, P.I.K. (2017) Regional Sea-Level at the Retreating Coast of Ghana under a Changing Climate. PhD. Dissertation, Universität Hamburg, Hamburg.

[41]   Ondoa, G.A., Bonou, F., Tomety, F.S., du Penhoat, Y., Perret, C., Degbe, C.G.E. and Almar, R. (2017) Beach Response to Wave Forcing from Event to Inter-Annual Time Scales at Grand Popo, Benin (Gulf of Guinea). Water, 9, 447.

[42]   Osinowo, A.A., Okogbue, E.C., Eresanya, E.O. and Akande, O.S. (2018) Extreme Significant Wave Height Climate in the Gulf of Guinea. African Journal of Marine Science, 40, 407-421.

[43]   Almar Kestenare, E., Reyns, J., Jouanno, J., Anthony, E.J., Laibi, R., Hemer, M., Du Penhoat, Y. and Ranasinghe, R. (2015) Response of the Bight of Benin (Gulf of Guinea, West Africa) Coastline to Anthropogenic and Natural Forcing, Part 1: Wave Climate Variability and Impacts on the Longshore Sediment, R., Transport. Continental Shelf Research, 110, 48-59.

[44]   Hubert, P. and Carbonnel, J.P. (1989) Segmentation of the Hydrometric Series. Application to Rainfall and Flow Series of West Africa. Journal of Hydrology, 110, 349-367.

[45]   Alamou, E., Gandomè, A., Quenum, M.L.D., Lawin, E.A., Badou, D.F. and Afouda, A.A. (2016) Spatio-Temporal Variability of Rainfall in the Ouémé Basin, Bénin. Afrique Science, 12, 315-328.

[46]   Ochou, A.D., Angora Aman, A., Kouadio, Y.K. and Assamoi, P. (2005) New Climate Zoning Based on Rainfall Variability in Cote d’Ivoire and Ghana. Revue de Géographie Tropicale et d’environnement, 5, 34-46.

[47]   Anani, L.S-A. (2013) Population Mobility in the Fluvio-Lagoon Complex of the Lower Ouémé Valley in Benin, West Africa. PhD Thesis, University of Abomey Calavi, Cotonou, 356 p.

[48]   Folorunsho, R., Awosika, L.F. and Dublin-Green, C.O. (1998) An Assessment of River Inputs into the Gulf of Guinea. In: Ibe, A.C., Awosika, L.F. and Aka, K., Eds., Nearshore Dynamics and Sedimentology of the Gulf of Guinea, IOC/UNIDO, CEDA Press, Cotonou, 163-172.

[49]   UNEP (1999) Regional Overview of Land-Based Sources and Activities Affecting the Coastal and Associated Freshwater Environment in the West and Central African Region. UNEP/GPA Co-Ordination Office & West and Central Africa Action Plan, Regional Co-Ordinating Unit, 110 p.

[50]   Adegoke, J.O. and Ologunorisa, T.E. (2010) An Assessment of Recent Changes in the Niger Delta Coastline Using Satellite Imagery. Journal of Sustainable Development, 3, 277-296.

[51]   Appeaning Addo, K. (2015) Monitoring Sea Level Rise-Induced Hazards along the Coast of Accra in Ghana. Natural Hazards, 78, 1293-1307.