‘Green Roads’ Are Plowing Ahead, Buffering Drought and Floods

Makueni County, a corner of southern Kenya that’s home to nearly a million people, is a land of extremes. Nine months a year, Makueni is a hardened, sun-scorched place where crops struggle and plumes of orange dust billow from dirt roads. Twice yearly, though, the county is battered by weeks of torrential rain, which drown farm fields and transform roads into impassable morasses. “Water,” says Michael Maluki, a Makueni County engineer, “is the enemy of roads.”

Maluki’s axiom is true the world over: Where roads and water intersect, trouble follows. Roads cut off streams and bleed sediment; meanwhile, floods often erode roadbeds into muddy gullies. Although wealthy nations are far from immune, these problems are most severe in developing countries, where roads are largely unpaved and thus especially vulnerable to…