Lagos faces fresh flood threat as NiHSA Flags 15 States

….Why Lagos remains vulnerable

Lagos is facing a fresh flood threat as the Nigeria Hydrological Services Agency (NiHSA) places the state among 15 states at heightened risk of riverine flooding between September 19 and 25, raising renewed concerns about the city’s drainage capacity, shrinking wetlands and exposure of densely populated communities.

The warning, contained in NiHSA’s Flood Alert NFA-2026-262, is based on projections of rising water levels in rivers and streams across the affected states. The other states are Imo, Cross River, Ebonyi, Benue, Anambra, Akwa Ibom, Rivers, Edo, Kogi, Taraba, Delta, Bayelsa, Enugu and Abia.

The alert comes against the backdrop of repeated flooding incidents in Lagos this year, with the agency’s flood dashboard recently identifying Lagos Island as facing major/destructive flood conditions associated with heavy rainfall and high tide.

Why Lagos remains vulnerable

Investigations by researchers increasingly point to a combination of natural and human factors behind Lagos’ worsening flood exposure.

A 2026 study published in Scientific Reports found that rapid urbanisation between 1984 and 2023 was accompanied by a substantial decline in forests and water bodies, reducing the megacity’s natural capacity to absorb and retain excess water. The study projected further expansion of flood-exposed built-up areas if current land-use trends continue.

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Another recent study focusing on the Lagos Lagoon corridor found that coastal areas such as Eti-Osa have particularly high flood exposure, while rainfall, proximity to rivers and population density are among the factors driving susceptibility.

Researchers have also warned that Lagos’ low-lying coastal geography is being compounded by sea-level rise and vertical land movement, creating additional pressure on an already vulnerable drainage system.

Urban planner Tpl. Niyi Aderohunmu, speaking on Lagos flooding, attributed part of the problem to the replacement of wetlands and mangroves with residential and commercial developments. He argued that these natural systems previously absorbed and gradually released stormwater, whereas extensive concrete surfaces accelerate runoff.

Geographer Abeeb Babajide Ajagbe and environmental resource management expert Gbenga Oloniniran have similarly pointed to continued development in flood-prone areas and the loss of natural flood buffers as factors worsening Lagos’ vulnerability.

Nine river stations require attention

NiHSA Director-General and Chief Executive Officer, Umar Mohammed, said nine river monitoring stations had been identified for close monitoring because of the flood threat.

Although the agency specifically highlighted Obubra, Itigidi and Epento along the Cross River, the inclusion of Lagos in the alert is significant because flooding in the state can arise from the interaction of intense rainfall, inadequate drainage capacity, rising lagoon levels and high tides.

Lagos State authorities had previously attributed some flooding episodes to elevated lagoon water levels, which can prevent stormwater from draining efficiently.

Critical infrastructure at risk

NiHSA’s assessment indicates that the consequences could extend beyond residential areas to schools, healthcare facilities, markets, religious centres, farms and other essential infrastructure.

In Cross River alone, the agency identified 2,471 communities, 703 schools, 344 health facilities, 145 markets, 453 religious centres and 854 hectares of farmland within areas exposed to flood risks.

For Lagos, experts say the concern is particularly acute because of the state’s dense population and extensive development around waterways, lagoons and wetlands.

Recent research has also found that even moderate rainfall can produce severe flooding where drainage systems, flood warnings and other protective infrastructure are inadequate.

Experts call for shift from emergency response

Aderohunmu has advocated a “blue-green” approach that combines conventional drainage and flood-control infrastructure with the protection and restoration of wetlands, floodplains and natural drainage corridors. He also called for stronger development control and hydrological assessments before construction in vulnerable areas.

Other experts have recommended expanded drainage and pumping infrastructure, flood-storage systems and stricter protection of wetlands.

The Lagos State Government has itself been pursuing measures aimed at improving flood resilience, including drainage desilting, enforcement around drainage alignments and a longer-term blue-green drainage strategy involving canals, pumps, estate lakes, flap gates and wetland restoration.

NiHSA issues emergency warning

Mohammed urged state governments, local government authorities, emergency management agencies, traditional rulers and community leaders to activate preventive measures immediately.

Residents in vulnerable areas were advised to move people, livestock and valuables to higher ground where necessary, while authorities were asked to prepare temporary shelters and pre-position relief materials, safe drinking water, water-treatment supplies and first-aid equipment.

NiHSA also warned residents against attempting to cross flooded roads, bridges or fast-moving water, either on foot or in vehicles.

The agency urged communities to clear blocked drainage channels and river outlets where it is safe to do so, while discouraging construction and habitation in flood-prone areas.

With the September 19–25 alert window now underway, the warning places renewed pressure on Lagos and other affected states to move beyond flood reaction and strengthen preventive measures before rising water levels translate into another round of disruption, displacement and property damage.