Floods are increasingly devastating African cities, exposing a long-ignored urban crisis. In April 2022, heavy rains pounded South Africa’s KwaZulu-Natal province, triggering deadly floods that killed nearly 448 people, displaced 40,000, and destroyed over 12,000 houses. Informal settlements suffered the most damage. Homes built on unstable land collapsed. Makeshift roads turned into raging rivers. Residents, many of whom had nowhere else to go, watched as their lives were washed away.
The pattern repeats itself across the continent. In July 2024, in Nairobi, Kenya, more than 400,000 people were affected by recent flooding, with around 40,000 households in informal settlements forced to relocate. Despite early warning signals, the city’s drainage systems failed, leading to widespread destruction and loss of life. In September 2024, in Nigeria’s Borno State, heavy rains flooded the area, killing over 37 people and injuring another 58. More than 400,000 people were affected by the heavy downpour.
Africa is urbanizing faster than any other continent. By 2050, its urban population is expected to triple, reaching 1.3 billion. Yet, this growth is not matched by adequate housing, infrastructure, or governance. Over 60% of urban dwellers in sub-Saharan Africa live in informal settlements. These areas, often built on floodplains, steep slopes, or other high-risk zones, are disproportionately vulnerable to extreme weather events like floods.
How Informal Settlements Amplify Flood Risks
Poor urban planning, weak governance, and economic inequality force millions into precarious living conditions. Take Nairobi’s Mathare slum, home to over 500,000 people. The settlement sits on a floodplain, crisscrossed by the polluted Mathare River. When heavy rains come, the river overflows, inundating homes with water mixed with raw sewage.
Residents lose belongings, livelihoods, and sometimes lives. “Last year, the floods destroyed my house,” says Jane Wanjiru, a Mathare resident. “I lost everything: my clothes, my children’s school books, even my small business. We had to start from zero.” Across Africa, informal settlements are hotspots for flood-related disasters. Their location in high-risk areas combined with poor construction and a lack of drainage systems makes them particularly susceptible.
The Data Behind the Crisis
The numbers paint a grim picture. According to the World Bank, floods in sub-Saharan Africa affected over 1.81 billion people in 2022 alone. Economic losses exceeded $4 billion. Informal settlements bore the brunt of these impacts. A 2021 study by the African Population and Health Research Center found that residents of informal settlements are 50% more likely to experience flood damage than those in formal neighborhoods. The study also revealed that flood-related health risks, such as waterborne diseases, are significantly higher in these areas.
“Floods don’t just destroy homes,” said Prof. Samuel Owuor, Associate Professor in Urban Geography at the Department of Geography and Environmental Studies, University of Nairobi, Kenya. “They disrupt lives, spread disease, and deepen poverty. The impact is long-lasting.” People settle on floodplains or near rivers because land is cheaper and more available. In South Sudan, entire villages along the Jonglei Canal are regularly submerged, with homes and livelihoods lost each rainy season. Another flooding occurred in Mali in September 2024, displacing nearly 343,900 people. Informal settlements bore the brunt of the destruction. The heavy downpour was considered the worst in 60 years.
Poor infrastructure further amplifies the problem. Informal settlements lack proper drainage systems, allowing water to accumulate and create flood conditions even after moderate rainfall. In Nigeria’s Maiduguri city, heavy rains overwhelmed the city’s infrastructure, leading to dam overflows that submerged entire neighborhoods, killing over 1,000 people. Without proper planning, these disasters will continue to occur.
Why Informal Settlements Keep Growing
Africa’s urban population is growing at an unprecedented rate. More than half of the continent’s people will live in cities by 2050. Many governments have failed to keep up with this growth, leaving millions to build their own homes in unplanned, poorly serviced settlements.
In Durban’s eThekwini Municipality, which has the largest number of informal settlements in South Africa, 314,000 households live in makeshift structures. Many of these homes sit on steep slopes or flood-prone areas, putting residents at constant risk. The growth of informal settlements is a direct consequence of Africa’s urban housing crisis. Cities are expanding, but affordable housing is not. In Lagos, Nigeria, for example, only 10% of the population can afford formal housing. The rest are forced into informal settlements, where they face constant risks.
“The government doesn’t provide affordable housing,” said Chinedu Okoro, a Lagos-based urban planner. “People have no choice but to build wherever they can, even if it’s unsafe.”
The Human Cost of Neglect
The impact of floods on informal settlements goes beyond physical damage. It disrupts livelihoods, deepens poverty, and exacerbates inequality. In Durban, many flood victims were informal traders who lost their goods and tools. “I used to sell vegetables at the market,” said Thandiwe Mkhize, a mother of three.
“The floods destroyed my stall and all my stock. Now I have nothing.” Children are particularly vulnerable. Floods often force schools to close, disrupting education. In Mathare, many children miss weeks of school each year due to flooding. “When the floods come, we can’t go to school,” said 12-year-old Kevin Ochieng. “Sometimes our books get washed away. It’s hard to catch up.”
A Crisis Compounded by Climate Change
Prof. Owuor said efforts to address these challenges must begin with improved urban planning. Governments need to recognize informal settlements as part of the urban fabric and provide essential services. Upgrading infrastructure, particularly drainage and waste management systems, can significantly reduce flood risks.
Community engagement is equally important. Informal settlement residents are experts in their own environment and must be included in decision-making. In Malawi, involving communities in flood vulnerability assessments has helped authorities develop better disaster preparedness strategies. Solutions that work for residents, rather than those imposed from above, are more likely to be sustainable and effective.
Climate change is intensifying the flood risk. Rising global temperatures are leading to more frequent and severe rainfall in many parts of Africa. According to the Intergovernmental Panel on Climate Change, extreme weather events like floods will become more common as the planet warms.
“Climate change is a threat multiplier,” said Dr. Fatima Denton, Director of the United Nations University Institute for Natural Resources in Africa. “It exacerbates existing vulnerabilities, particularly in informal settlements.”
Potential solutions
Addressing the flood risk in informal settlements requires a multipronged approach. Governments must invest in affordable housing. This means building more low-cost homes and upgrading existing informal settlements. In Rwanda, the government’s efforts to provide affordable housing have reduced the growth of informal settlements in Kigali.
Urban planning must be prioritized. Cities need comprehensive land-use plans that designate safe areas for development and enforce building codes. In Ethiopia, the government’s Integrated Housing Development Program has improved urban planning and reduced flood risks in Addis Ababa.
Drainage systems must be improved. Many informal settlements lack proper drainage, making them prone to flooding. In Nairobi, the construction of new drainage channels in Mathare has reduced flood damage.
Community involvement is crucial. Residents of informal settlements must be included in decision-making processes. They know the risks and challenges better than anyone. “We need to listen to the people living in these areas,” says Dr. Owuor. “They have the knowledge and experience to help find solutions.”
