When floodwaters swept through pockets of Lagos in July, disrupting commerce and traffic for days, the immediate cause was heavy rainfall. A growing body of research points to a deeper, slower-moving driver, however: the steady disappearance of the wetlands that once absorbed that water before it ever reached the streets.
Lagos: the numbers behind the flooding
A study published in June, examining satellite images of Lekki — one of Lagos’s most densely populated districts — between 2015 and 2025, found that vegetation cover had fallen by 13% over the decade, while water bodies shrank by 6%. Over the same period, settlements expanded by 10% onto what was previously natural land cover, a shift researchers linked directly to the area’s worsening flood events.
That study joins a wider pattern. A separate analysis published in February found that built-up areas across Lagos expanded by 38% between 1984 and 2023, while forest cover fell by 32% and water bodies shrank by 11%, eroding what researchers called the city’s “natural flood buffering capacity.” If current trends continue, the same study projected, more than 60% of Lagos’s urban areas will face extreme flooding by 2050.
Mark Ofua, West Africa Representative for the conservation non-profit Wild Africa, attributes the loss directly to development pressure. “Lagos was historically surrounded by extensive wetlands and mangroves, but everywhere you turn now, especially around the suburbs, there’s land reclamation and construction going on,” he told Mongabay in an interview.
A separate analysis by World Weather Attribution, a network of scientists who study extreme weather events, reached a similar conclusion: the sprawl of housing onto wetlands that would otherwise absorb excess rainfall is placing low-lying coastal cities such as Lagos at elevated flood risk.
Arepo: a wetland community becomes a flood-alert zone
The pattern extends beyond Lagos’s own borders. In Arepo, a fast-growing residential suburb in Obafemi Owode Local Government Area of neighbouring Ogun State, several hectares of wetland have been cleared and are being filled in for residential estates — part of a real estate expansion that has seen the area rebranded by developers as “New Lagos.”
The consequences are now showing up in official warnings. On September 1, Ola Oresanya, Commissioner for Environment in Ogun State, issued a flood alert explicitly naming Arepo among the communities at risk, citing controlled overflow from the Oyan Dam and tidal fluctuations that could “impede the flow velocity of the Ogun River.” The combined effect, he warned, could cause temporary oversaturation of wetlands and floodplains, heightening flood risk in vulnerable communities, including Arepo, Isheri, Mawere, Magboro, Akute and Warewa. Residents were advised to remain vigilant and relocate where necessary. The advisory did not name individual developers, but it confirms, in official terms, what Wild Africa’s Ofua describes happening around Lagos more broadly: land once capable of absorbing floodwater is being converted into hard, built surfaces faster than replacement drainage capacity can keep pace.
Calabar: the same story, a different coastline
Further east, in Cross River State, a similar dynamic has been documented over a longer timeframe. Academic research into wetland encroachment in Calabar South Local Government Area has tracked a marked reduction in wetland cover as urbanisation expands, stripping away natural flood receptors and pollution filters that researchers describe as the “kidneys” of the local ecosystem. A separate land-use study of the wider Calabar River catchment found that high forest cover fell from nearly 70% of the basin area in 1967 to under 40% by 2008, while built-up land more than doubled over the same period.
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The results are visible on the ground. In Efut Efio-Ene, a community in Calabar South, the traditional ruler, His Royal Highness Muri Ekong Umo Ekpo II, said stormwater channelled from across Calabar metropolis flows directly into the community, destroying homes, contaminating drinking water and displacing residents — a pattern he attributed to a poorly maintained drainage system. Nearby, in Arab and Atimbo communities, torrential rainfall in July destroyed property estimated at more than N50 million and submerged over 100 houses. Commentary on the wider Lagos-Calabar coastal road corridor has also flagged that wetlands and floodplains across Lekki, Ibeju-Lekki and adjoining coastal areas are increasingly being replaced with estates, roads and commercial developments, altering natural drainage paths that surrounding communities depend on.
An overlooked cost: what happens to wildlife
While the human toll of flooding is well documented, its effect on biodiversity remains far less understood. Sporadic reports have surfaced: in 2024, more than 80% of the animals at a zoo in northern Nigeria reportedly fled after severe flooding, including an ostrich later spotted wandering a nearby neighbourhood in a widely shared video clip. Researchers say cases like this hint at a largely unmeasured ecological cost of wetland loss and urban flooding, one that receives a fraction of the attention paid to property damage and displacement.
What experts say needs to change
For Ofua, the solution lies less in new technology than in enforcement of what already exists on paper. “The government has to declare these areas as protected and stop more companies from land reclamation,” he said. “We have to move from lip service to action.” Nigeria’s states have shown they are capable of identifying at-risk wetland communities, as Ogun’s alert demonstrates. The harder task, evident from Lagos to Arepo to Calabar, is stopping the conversion of those wetlands into estates before the next flood season arrives.
