Gullies are opening and expanding in African cities built on sandy soils and lacking adequate drainage, carving deep trenches that swallow homes, businesses and infrastructure. Heavy rains cause water to accumulate on roads and rooftops, and inadequate drainage allows water to flow into unprotected ground, carving holes that can stretch hundreds of metres and sometimes cause deaths. Satellite imagery from 2021–2023 identified 2,922 urban gullies across 26 of 47 cities, covering nearly 740 kilometres. Only 46 gullies were present in the 1950s. About 118,600 people in the DRC were displaced between 2004 and 2023. Without urgent action, hundreds of thousands more are likely to be displaced within 10 years.
Expanding gullies Gullies are expanding across cities that are built on sandy soils and lack adequate drainage. When there are heavy rains, water accumulates on roads and rooftops. When the drainage systems are inadequate, the water finds its way into unprotected ground, carving deep holes that can stretch for hundreds of metres. Over time, the gullies swallow houses and other infrastructure, and sometimes even result in deaths.
Vanmaercke and his colleagues used satellite images taken between 2021 and 2023 to identify 2,922 urban gullies in 26 of 47 cities, covering a cumulative distance of nearly 740 kilometres. The team cross-checked these images with historical aerial photographs stored at the Royal Museum for Central Africa in Belgium and found that only 46 of the gullies were present in the 1950s.
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