Problem:
Lagos, the most populous city in Africa (24 million) is also one of its most vulnerable to sea level rise and floods. But during the rainy seasons, the city’s streets can become almost impassable. If global warming exceeds 2C, the city is predicted to see 90cm of sea level rise by 2100, according to research led by marine physicist Svetlana Jevrejeva, of the UK’s National Oceanography Centre.
Solution:
Floating structures, ferryboat fleet, the Great Wall of Lagos, and groynes.
The suburb of Makoko, known as the “Venice of Africa”, is a labyrinthine slum built on stilts and navigated by canoe. The Makoko Floating School is a structure resting on recycled empty plastic barrels for buoyancy.
The school’s pyramid shape helped lower its centre of gravity and so increase its stability, while also being an ideal roof shape for shedding heavy rains
A floating music hub made from timber and consists of three floating vessels housing a multipurpose live performance hall, a state-of-the-art recording studio and a platform for thirsty guests. This is part of NLÉ’s African Water Cities project, which seeks to find new ways for waterfront communities to live with rising sea levels.
The Lagos State Waterways Authority now runs more than 42 ferry routes on the waterways with 30 commercial jetties and terminals spanning across three districts.
One prominent defence against rising waters is the “Great Wall of Lagos”, a barrier made of 100,000 concrete blocks weighing five tonnes each. The 18m-high (60 ft) sea defence protects a stretch of shoreline by Lagos’ Eko Atlantic, a development being built on reclaimed land, and will be 8.4km long when completed.
Other structures to protect the sea include constructing 18 groynes on the shores of the Eko Atlantic. A groyne is a structure built to trap sand and prevent it from washing into the ocean. Those installed at Eko Atlantic are each spaced 400m (1,300ft) apart and span a distance of 7.2km (4.5 miles). Further groynes have been proposed to cover up to 60km (37.3 miles) of the state’s coastline
Discover Solution 211: Xeriscaping
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