Imagine waking up to find that the ground beneath your home has split open, the earth itself giving way to a canyon that seems to appear overnight. Streets crumble, houses vanish, and neighborhoods that once thrived become landscapes of ruin. This is not a distant nightmare but a present reality for tens of thousands of families across Central Africa. Deep, yawning cracks in the earth—known as urban gullies—are ripping through cities, consuming roads, infrastructure, and lives.
A new study published in Nature has revealed just how enormous this threat has become, focusing on the Democratic Republic of the Congo (DRC). Scientists mapped 26 cities across the country and found an astonishing 2,922 massive gullies, each one a scar across the urban landscape. These are not small erosions; they are immense chasms that can stretch hundreds of meters, tearing apart entire communities. And they are spreading.
Between 2004 and 2023, these gullies displaced nearly 118,600 people in the DRC alone. Entire families have been forced to leave homes passed down through generations, while the land beneath their feet collapses into voids. The danger is accelerating—today, 3.2 million people live in areas at risk of being swallowed, double the number from just over a decade ago.
How Gullies Are Born
To understand the crisis, one must begin with the soil itself. Many Central African cities are built on sandy terrain and steep slopes—conditions that make the earth especially vulnerable to erosion. When rain falls, instead of soaking gently into the ground, it rushes downhill, carrying grains of soil with it. Over time, rivulets deepen into channels. Left unchecked, those channels can transform into colossal gullies, wide and deep enough to engulf homes, bridges, and entire streets.
But this is not just nature’s doing. Human activity has intensified the process. Rapid, unplanned urban growth means new houses, roads, and markets rise without proper infrastructure. Drainage systems are scarce or nonexistent. During heavy rains, water flows across rooftops and streets, gathering speed and force, funneling into concentrated streams that slice through unprotected ground. What begins as a trickle can become a torrent, and the land gives way.
The tragedy is that gullies often appear without warning. One night, the ground may seem solid; the next, it may collapse into a ravine meters deep. For families living at the edge, the earth is no longer a foundation but a threat.
The Human Toll
The numbers are staggering, but the human stories are even more devastating. A mother walking her children to school may find the path gone, cut off by a sudden canyon. Farmers may lose their land to a widening chasm, their livelihoods swallowed overnight. Communities once united are divided by jagged trenches, neighbors separated not by distance but by a gaping scar.
For those displaced, the trauma is lasting. Losing a home is not just losing walls and a roof—it is losing security, memory, and belonging. And for governments already struggling with limited resources, the economic cost of repairing destroyed infrastructure—roads, schools, water pipes—adds to the burden.
The crisis also exacerbates inequality. Wealthier families, with access to sturdier housing and safer land, are less affected, while poorer communities are forced to live on vulnerable slopes where gullies are most likely to form. The disaster, then, is not only geological but deeply social.
A Crisis Worsened by Climate Change
If the situation feels urgent now, it is poised to grow even more severe. Climate change is bringing heavier and more unpredictable rainfall to tropical regions. Storms that once happened every few years may now strike several times a season, unleashing downpours that overwhelm fragile soil and fragile cities.
Urban gullies are thus not just a local phenomenon but a global warning. As rainfall patterns intensify across the Global South, the conditions that create gullies will worsen. What scientists are seeing in the DRC is a glimpse of the future for many tropical cities unprepared for the dual challenge of rapid urbanization and climate disruption.
Paths Toward Prevention
The grim reality is that once a gully has formed, it is nearly impossible to reverse. Filling them in or building over them is costly and often temporary. The true solution lies in prevention—stopping small erosions from becoming catastrophic before the land collapses.
Scientists and urban planners argue that prevention must begin with awareness. Communities need to understand the risks and recognize the early signs of erosion. Local governments must prioritize drainage systems when planning new neighborhoods, ensuring that rainwater is safely channeled away before it can carve destructive paths.
Vegetation plays a powerful role too. Plants anchor soil, their roots acting as natural reinforcements against erosion. Planting trees, grasses, and shrubs around vulnerable areas can stabilize slopes and slow runoff. Structural barriers—stone walls, terraces, and engineered drainage channels—can also redirect water, protecting neighborhoods from collapse.
Above all, coordinated action is essential. Preventing gullies is not just an engineering challenge but a political and social one. It requires investment, long-term planning, and collaboration between governments, scientists, and communities.
A Choice for the Future
The crisis of urban gullies is not a distant problem. It is happening now, reshaping lives and landscapes across Central Africa and beyond. If left unchecked, millions more could be forced to abandon their homes in the coming decades, entire neighborhoods erased from the map.
Yet the story is not one of despair but of urgency. We have the knowledge to slow and even prevent this disaster. We know how gullies form, we know the human activities that accelerate them, and we know the tools that can hold them back. What remains is the will to act—before the ground beneath millions of people literally disappears.
Urban gullies are a reminder of how closely we live with the earth, and how fragile that relationship can be. The ground we walk on feels solid, but under pressure, it shifts, cracks, and opens. If we fail to respect the land and prepare for its power, it will take back what we have built.
But if we listen, if we learn, if we act, then perhaps these chasms need not define the future. Instead, they can serve as a warning—and an opportunity to build cities that are stronger, safer, and more resilient in the face of a changing world.
More information: Guy Ilombe Mawe et al, Mapping urban gullies in the Democratic Republic of the Congo, Nature (2025). DOI: 10.1038/s41586-025-09371-7
