6km long breakwater and beach restoration( 4 km + 2 km )
1-3ton heavy rocks on a filter bed in front of the coast
3million m³ beach nourishment on the eroded coastline
Jan De Nul controls coastal erosion in Benin through an innovative solution, conceived, developed and constructed in-house. An integrated project using the company’s competences, both technically, environmentally and financially.
The future of Benin
The West African coast is being ravaged by erosion. That includes Benin, where the incoming swell of the Atlantic Ocean hits the coastline, eroding between one to three metres each year. Without human intervention, climate change and the rising sea level will continue to erode the beaches of Benin. Structures that are typically proposed to stop erosion are groyne fields and dykes to prevent sand movement. Generally these types of preventive works have a mediocre efficiency, and move the problem to other coastal segments, or even have adverse effects for the development of the beaches, environmentally, socially or for tourists. Jan De Nul, on the other hand, proposed a sustainable and innovative solution inspired by natural systems: the functioning of coastal reefs.
It's the first time that the concept of an underwater breakwater has been implemented on this scale.
Envisioning touristic developments along the Benin coast, the Government of Benin ordered the Ministry of Environment and Sustainable Development to search for an innovative answer to stop the erosion problem without creating an imbalance along the coastline.
Jan De Nul has devised the concept of an underwater breakwater parallel to the coast combined with sand replenishment destined to restore the current beach to its original state. Senior Project manager Dredging Jan Moens explains: ‘The energy of the incoming ocean swell will be reduced by the underwater breakwater before reaching the shore. We drew our inspiration from coral reefs, which are also located in shallow water in front of the coast. Due to their position and structure, these reefs break the erosive power of the ocean swell and protect the coastal areas and islands.’ Imitating nature is a fine example of sustainability, all the more so because of the flexibility of the concept. Even if the sea level rises further than expected, the structure can easily be adapted. ‘This innovative concept is surely unconventional in the maritime world and has never been applied before on this scale. It is an idea that Jan De Nul has conceived, developed, engineered in detail and implemented.
From early 2018 and the next three years, Jan De Nul will be transporting rocks to the stockpile south of the port of Cotonou. Two thirds of the rocks come from quarries in Benin, 150km further inland, whilst the rest comes from abroad. ‘All the…
Whilst dumping rocks might not be new, creating a breakwater with 1 to 3 ton rocks up to a depth of -1m certainly is. Since a crane works too slowly to meet the tight deadlines, Jan De Nul has converted its side stone dumping vessel Pompei. The vessel…
A project of this scale obviously requires thorough planning and preparation. Jan De Nul conducted preliminary and conceptual design studies for this project, including geotechnical and geophysical site investigations, hydrometeorological analyses and…