The shores of the Gulf of Guinea threatened by submersion

On November 7, huge waves ravaged Ghana’s coastline in the Ketan region, east of the mouth of the Volta River. 500 seaside homes have been partially or totally destroyed, and 4,000 people are affected. A school and even a cemetery were flooded. The inhabitants are now homeless, refugees in churches or school groups, and await measures from the state.

The country is regularly struck by these waves of submersion, wrongly called tidal waves. “It’s the third of the year, but it was the biggest” acknowledges to AFP George Thus, of the national disaster management organization. “It is becoming worrisome, we have not experienced this for many years.”

Ghana is not the only country affected by this phenomenon in the Gulf of Guinea. Its neighbor, Côte d’Ivoire, is particularly affected, particularly in the bay of Abidjan and on the entire coast towards Ghana. For short periods, suddenly a violent swell from the open sea hits the seafront. The waves can reach seven meters high, causing enormous damage and accelerating erosion.

The phenomenon is rare, but occurs several times a year and is sometimes particularly destructive. Likewise, on the night of August 13-14, 2007, in Grand Bassam the coast retreated up to 18 meters in a single tide, while the erosion of the bay is on average only 1.5 m per year. In Port-Bouet in Côte d’Ivoire, waves destroyed 31 homes in the informal district, built without authorization.

Contrary to what is sometimes claimed, the rise in sea level is not the cause of the phenomenon. According to a study on the 2007 event in Côte d’Ivoire, this strong swell phenomenon was due to a slight earthquake near Ascension Island (4.8 on the Richter scale ). Not strong enough to create a tsunami, but enough to set off waves on the surface of the ocean which, parts of the middle of the South Atlantic, reached the mainland.

For the case of Ghana on November 7, no explanation has been provided. A high coefficient of 107 during high tide undoubtedly contributed to increase the phenomenon of submersion. The country has 550 kilometers of coast where nearly 8 million inhabitants live, or a quarter of the country, and the problems of erosion or marine submersion are becoming worrying.

Ghana has launched a project to “maritime defense”, consisting of laying boulders along the coasts to create dikes. A first phase of the project, covering 4.3 kilometers of coastline, was completed in 2019. Ghana’s Minister of Works and Housing, Francis Asenso Boakye, said the government would “to start work soon” of the second phase, which will cover at least eight kilometers.

The 3600 kilometers along the coast, along the Gulf of Guinea are home to 40% of the region’s 300 million inhabitants, from Liberia, the most western country, to Angola, the most southerly. So many inhabitants threatened by the ocean.

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