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The April 2025 , the capital of the Democratic Republic of Congo, wasn't just about intense rainfall. It was a symptom of recent land use change which has occurred rapidly in the city, turning it into a sprawling urban settlement without the necessary drainage infrastructure.

Local rains combined with runoff from torrential rains coming from neighboring Congo Central Province quickly overwhelmed the city's small urban tributaries. The Ndjili River and its tributary (Lukaya), which run through the city, overflowed and flooded homes on either side.

This led to the of at least 70 people, 150 injured and the temporary displacement of more than 21,000 people. Floods affected the running of 73 health care facilities. Access to water and transport services were disrupted in large parts of the city. People could only move around by dugout canoe or by swimming in flooded avenues.

Floods have become recurrent in the DRC. The last quarter of and the beginning of saw the most devastating floods there and in neighboring countries since the 1960s.

According to UN World Urbanization Prospects (2025), the reason the floods have become this devastating is the growth of Kinshasa. The city is the most densely populated city in the DRC, the most populous city and metropolitan area in Africa.

Kinshasa's is estimated at 17,778,500. Back in 1950, it was 201,905. In the past year alone, the city's population has grown by 746,200, a 4.38% annual change. At least 2% of the population live in areas prone to flooding.

Urban infrastructure, especially flood-related, is non-existent or inadequate. Where it exists, drainage systems are blocked by solid waste, itself another sign of the city whose public services such as waste collection have become dysfunctional.

We have been studying the characteristics of flooding and the prediction of risk linked to it in the Congo Basin for five years as part of our at the Congo Basin Water Resources Research Center in Kinshasa. We study the movement of water in natural and modified environments and its interactions with infrastructure over a range of geographical scales. We argue in this article that understanding why Kinshasa floods means recognizing two very different water systems at play—and how urban growth has made the city more vulnerable to both.

Kinshasa faces two distinct flood hazards: first, flooding from the Congo River, which typically peaks around December and January; and, second, urban flood events driven by local rainfall and runoff from the hills south of the city around April and December.

Most of Kinshasa's flood disasters have come from the second type. And as Kinshasa has urbanized, expanding into the floodplains, but without the necessary urban infrastructure, the impact of urban flood events has become worse.

With more sealed surfaces—because of more urban settlements—and less natural water absorption, more rainwater runs off, and faster. This overwhelms the city's small urban tributaries and the Ndjili River.

Growth of Kinshasa and flood

As the city has expanded, so has its flood exposure. The city's tributaries drain steep, densely populated urban slopes and are highly responsive to rainfall.

Of Kinshasa's two flood risks, the impact of Congo River flooding can be observed in large cities located along major rivers, and typically peaks around January. These are seasonal floods driven by rainfall across the whole Congo Basin.

Research at shows that while Congo River high water levels can cause "backwater effects"—the upstream rise in water level caused by reduced flow downstream—most damaging floods result from intense local rainfall overwhelming the city's small river catchments. The flood risk indicates that 38 territories are the hotspot of flooding in the Congo Basin. Kinshasa is a hotspot due to its double risk sources and extensive urbanization.

The urban flood events are more challenging. They can happen with less rainfall and cause major destruction. They are driven by local rainfall and rapid growth of informal settlements.

Other cities face similar risks. In 2024, Nairobi after prolonged rain overwhelmed informal neighborhoods and infrastructure.

Across Africa, cities are growing faster than their infrastructure can keep up with. Kinshasa has unique exposure, but also strong local research capacity.

The Congo River's seasonal peaks are relatively well understood and monitored. But urban tributaries are harder to predict.

DRC's meteorological agency Mettelsat and its are building capacity for real-time monitoring. But the April 2025 showed that community-level warning systems did not work.

Climate change is expected to intensify extreme rainfall in central Africa. While annual totals may not increase, short, intense storms could become more frequent.

This increases pressure on cities already struggling with today's rains. In Kinshasa, the case for climate-resilient planning and infrastructure is urgent.

What needs to change?

Forecasting rainfall is not enough. Government agencies in collaboration with universities must also forecast flood impact—and ensure people can act on the warnings. There is a need to put in place systems to achieve this under a catchment integrated flood management plan.

The main elements of such a plan include:

• Improved early warning systems: Use advanced technologies (such as satellites) to gather real-time data on environmental conditions.
• Upgraded drainage infrastructure: Identify weaknesses and areas prone to flooding, to manage storm water better.
• Enforcement of land use planning: Establish clear regulations that define flood-prone areas; outline permissible land uses.
• Define safety perimeters around areas at risk of flooding: Use historical data, flood maps, and hydrological studies to pinpoint areas that are at risk. Regulate development and activities there.
• Local engagement in flood preparedness: Educate residents about flood risks, preparedness measures, and emergency response.

Institutions such as the Congo Basin Water Resources Research Center play a critical role, not just in research but in turning knowledge into action. Rainfall may trigger the flood, but urban systems decide whether it becomes a disaster. And those systems can change.

This article is republished from under a Creative Commons license. Read the .