Flooding

Flooding happens when water covers land that is normally dry. It comes in a few forms: river flooding, when a river overflows its banks after heavy rain upstream; flash or urban flooding, when rain falls faster than drains can carry it away; coastal flooding, when high tides and ocean surges push water onto low-lying land; and sudden flooding when a dam overflows or fails.

Floods are among the most common and costly natural disasters. They damage homes, farms and roads, and they can kill people within minutes when water rises fast.

Heavy rainfall. Intense rain over a short period can overwhelm drains and rivers. When a large volume of water arrives faster than the ground and channels can handle, streets and low areas flood.

Blocked or inadequate drainage. Drains clogged with refuse, or too few drains for a growing city, cannot carry stormwater away. Waste dumped into gutters and canals is one of the causes that residents can prevent directly.

Low-lying land and high tides. Coastal cities sit close to sea level. When the ocean or lagoon is high, stormwater cannot flow out, so drains back up and spill into the streets until the tide drops.

Building on waterways. Houses, shops and structures built on drainage paths and floodplains reduce the space water needs to flow, and they put people directly in its way.

Water from upstream and dams. Heavy rain or dam releases in one place can flood communities far downstream, and dams that fail send a sudden surge of water into nearby towns.

Climate change. A NEMA official has said that rapid climate change has increased how often natural disasters occur in Nigeria. The local science is still being studied.

On people. Floods kill, injure and displace people, who often shelter in schools and public buildings. Floodwater can hide debris and contain harmful things, so contact with it is a health risk.

On homes and services. Floods destroy houses, close schools and health centres, cut roads and halt business, especially for small traders who cannot easily recover.

On food and farming. Floods wash away crops and farmland. This matters most in northern Nigeria, which produces much of the country's food, and it can push up food prices.

On recovery. Recovery takes a long time. Displaced families may spend months away from home, and rebuilding costs fall hardest on people with the least savings.

Before the rains - Never throw waste into drains, gutters or canals. - Find out whether your street or home is in a flood-prone area, and where the nearest higher ground is. - Follow seasonal forecasts from NiMet, flood outlooks from NIHSA, and warnings from NEMA or your state emergency agency. - Keep important documents in waterproof bags, and keep a charged phone and torch ready.

During a flood - Move to higher ground early. Do not wait for the water to rise. - Do not walk or drive into floodwater. Just 15 cm (6 inches) of fast-moving water can knock an adult off their feet, 30 cm (12 inches) can carry away a small car, and about 60 cm (2 feet) can carry away most vehicles. Over half of flood drownings happen when people drive into floodwater, and walking into floodwater is the next most common cause (US CDC). - Stay away from electricity. Do not enter a room if water covers sockets or cords. - Avoid contact with floodwater where you can.

After a flood - Wash with soap and clean water if you touched floodwater, and wash contaminated clothes in hot water and detergent. - Watch for debris and damaged roads or structures as water recedes.

As a community - Organise regular drain clearing on your street, and report blocked channels to your local authority. - Do not build or trade on drainage paths, and support enforcement of setbacks.

Nigeria records flooding every year, often linked to weak enforcement of environmental guidelines and inadequate infrastructure.

2012. NEMA reported at least 363 people killed and over 2.1 million displaced.

2022. NEMA described it as unprecedented in Nigeria's history. NEMA's Director General later stated that 662 people died, 3,174 were injured and 2,430,445 were displaced. Other reports from the same period give lower figures (for example, over 500 deaths and 1.4 million displaced), because counts changed over time and sources differ. Bayelsa was among the worst affected states, and Jigawa recorded 91 deaths by mid-September. Nigeria's hydrological agency (NIHSA) linked the flooding partly to heavy rainfall and external flows such as a dam in Cameroon.

2024. On 10 September the Alau Dam near Maiduguri collapsed after weeks of heavy rain, flooding large parts of the city. An early NEMA count was at least 30 dead and over 400,000 displaced, though later estimates differ widely. The UN World Food Programme said around 800,000 people in 29 states were affected by floods by September 2024, and more than 550,000 hectares of cropland were flooded.

Lagos. Lagos is a low-lying coastal city. Lagos State's environment commissioner has explained that when the Atlantic Ocean and the Lagoon are high, stormwater cannot drain out, so drains back up into the streets until the tide drops, a process officials call "lock up". After flooding in late June 2026 hit areas including Victoria Island, Lekki, Ikeja, Gbagada and Mushin, Governor Sanwo-Olu approved dredging of 28 additional primary drainage channels. State officials have repeatedly urged residents not to dump waste in drains. An urban planner has also pointed to buildings encroaching on waterways and weak enforcement of setbacks as causes.

Who issues warnings. NiMet publishes seasonal climate predictions, NIHSA publishes the annual flood outlook, and NEMA coordinates emergency response. Following their updates before and during the rainy season is one of the most practical protections available.