July 28, 2021

In Benin, the fight against maritime erosion scores points

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Two groynes built to protect the coast of Benin, east of Cotonou, in 2020.

The ocean eventually receded. 150 meters on average, 180 meters in places. East of Cotonou, the economic capital of Benin, a long sandy beach now stretches for about fifteen kilometers along the road that leads to Nigeria.

Near the shore, buildings under construction, a few hotels and, near the waves, restaurants where families come to eat braised fish with their feet in the sand. “We feel safe today, ensures the manager of the Port Abobo maquis. A few years ago, the sea washed away tables, chairs and umbrellas. ”

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In the districts of Enagnon, Donaten or Akpakpa-Dodomè, dozens of houses were destroyed by the assaults of the Atlantic Ocean. “The danger was real, assures Philippe Zoumenou, coordinator of coastal protection programs against coastal erosion in Benin. Residents were swept away in their sleep and drowned. During high tides, the districts, completely inundated, could remain isolated from the rest of the city for several days. ”

This standoff between land and sea has always existed. But the construction of the port of Cotonou in 1964 played on the various forces. By modifying the natural dynamics of the coast, the construction of the port area, considered today as the third port in West Africa after Lagos and Abidjan and which generates 60% of Benin’s GDP, has led to an accretion of sand in upstream (west of the port) and erosion downstream (east).

Work started in 2012

Also because of massive urbanization, the increase in maritime traffic in the Gulf of Guinea and the frequency of strong seasonal storms, this maritime erosion has accelerated to reach “An average speed of ten meters per year”, specifies Philippe Zoumenou.

In addition to swallowing up infrastructure and contributing to the disappearance of Benin’s territory, it has caused ecosystem degradation. “We were heading straight for an ecological disaster, deplores William Tchoki, journalist specializing in the environment on Beninese television (ORTB). The site is a breeding ground for sea turtles. “

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The first studies to identify the phenomenon of erosion east of Cotonou were carried out in 2003 by a Canadian office. But the site did not start until 2012 as part of a first phase of work which allowed the construction of eight ears. These protective structures, which are anchored on the beach and can measure up to 300 meters in length (like that of Siafato), slow down the currents and limit the movement of sediments. Trapezoidal in shape for “Break” the power of the waves, they consist of a riprap of some 60,000 tonnes of stones of different sizes. However, they were not enough to defend the coast against the onslaught of the waves.

A titanic site

Due to several port improvements which were completed in 2011 and the rising water levels linked to global warming, these first groynes turned out to be insufficient. “It is impossible to know how many buildings and houses were washed away, indicates William Tchoki. In the embassy district, people lived with fear in their stomachs. “ An association of residents then mobilized.

“The Beninese State was aware of the advance of the sea, but there were some administrative delays, remembers Doris Alapini, owner of the Biergarten, a beach restaurant located at the mouth of the Cotonou lagoon. We encountered a lot of obstacles to make our voice heard, but in the end we succeeded. “

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After the particularly devastating high tides of April 2016, the government of Patrice Talon, just elected at the head of Benin, then launched several actions to counter erosion. After modeling studies of the maritime facades, a new coastal protection program has started, comprising the rip-rap of the coast and the reloading with sand of the segments on the coast located to the east of Cotonou. This titanic site saw the laying of nearly a kilometer of groynes (4.5 million cubic meters) and 600 meters of submerged dyke.

Project of an imposing tourist complex

“This second phase, which ended in January 2019, made it possible to erect four other groynes, as well as three cladding walls to stabilize the coast and support the upper beach, explains Philippe Zoumenou. Nearly 150 hectares of beach have been restored for a total amount of 53 billion CFA francs [près de 81 millions d’euros] ». A sand reserve has also been set up for future projects.

The fight against coastal erosion in Benin – which has 125 kilometers of coastline – now also extends to the west: in Ouidah, a former slave port which intends to rely on memorial tourism to develop, and Grand -Popo, a stone’s throw from the Togolese border.

In Cotonou, the construction of the last four ears of corn should allow the creation of a marine lake and an imposing tourist complex to develop nautical and seaside activities. “Quality works have been carried out, Doris Alapini analysis. But the plan to now create a cornice is risky without a dredging operation and the construction of a protective dike. It risks destroying all the efforts that have been made. ”

Against this ledge that would serve the new tourist complex along the shore, the inhabitants of the Jak district are mobilizing. “There was not enough consultation with local residents to collect all the necessary data”, denounces Doris Alapini, for whom this project does not take into account the safety of the inhabitants.