This awesome story originally appeared on Yale Environment 360 and is part of the Climate Desk collaboration.
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. However, twice yearly, 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 obliteration. In Kenya and other nations, the issue is exacerbated by climate change, which has amplified the intensity of seasonal monsoons and droughts.
In 2019, Maluki began to ponder how to reconcile two of his county’s challenges: the aridity of its dry season and the destructiveness of its wet season. That year, he and colleagues attended a local workshop led by a Dutch consulting firm called MetaMeta on the concept of “Green Roads for Water”—a set of precepts for designing roads to capture water through strategic channels, culverts, and ponds and divert it for agricultural use. After being inspired by the session, Maluki brought the idea to his colleagues and local farmers, who gave Green Roads their cautious blessing.
Makueni County’s Green Roads quickly proved their worth. Along roadsides, Maluki’s team members installed “mitre drains,” which shunted floodwaters into newly dug channels that irrigated mangoes, bananas, and oranges. They excavated farm ponds, which stored the rainy season’s floodwaters for use during drought, and they planted roadside fruit trees to absorb runoff and help control the dust that billowed from unpaved roads. And where travel routes crossed ephemeral rivers at right angles, the county built drifts—concrete road segments that also functioned as makeshift dams. During seasonal floods, the drifts captured deep banks of sand on their upstream sides. The sand retained pockets of water, which farmers tapped during the dry season via four-foot-deep wells dug upstream of the drift. In neighboring Kitui County, one study found that every $400 spent on similar low-tech tweaks increased farmers’ yields by around $1,000; according to Maluki, they’ve also made the rainy season far less damaging.
“The biggest asset for [the county government] in this program is the reduction of maintenance costs,” Maluki says. “It’s a two-way benefit.” He estimates that between 5 and 10 percent of the counties’ roads now apply water-harvesting principles.
Southern Kenya isn’t the only place seeing such gains: Nearly 20 countries have either implemented Green Roads for Water or plan to begin soon, and thousands of kilometers of roads,