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.

Nope.