Story
Kenya
Building Riverbeds from Sand Dams
G
lobally, 500 million smallholder farmers provide up to 80 percent of food consumed in most of the developing world. Most of these farmers rely on rain-fed agriculture. In the drylands, climate change is causing more droughts and floods as well as shorter, more unpredictable rainfall. It is reducing the ability of these farmers to grow food. Eighty-four
percent of Kenya is drylands, and the rainfall is increasingly unpredictable, variable, and infrequent. And when it rains, up to 85 percent of the water may be lost as runoff, washing away fertile topsoil and seeds and undercutting food production. Makueni County in Kenya is typical. An estimated 57 percent of the households lack access to an improved water source. On average, women and children spend four and a half hours a day collecting water. In times of drought, it takes up to 12 hours, which leaves little time to invest in sustainable land management and food production. It is not surprising that Makueni County has a Human Development Index of 0.558 and that 31.1 percent of its children are underweight. But a study conducted in Kenya in 1999 showed that where sand dams were built, households suffering from malnutrition declined from 32 to 0 percent, and incomes significantly increased. Guided by the principle that poverty alleviation in drylands can only be achieved through sustained investment in soil and water conservation, Excellent Development began working with self-help groups in Makueni in 2002, with the sand dam as the technology of choice. A sand dam is a reinforced concrete wall that is built across a seasonal sandy river. During the rainy season, the river carries silt and sand downstream. The heavy sand accumulates behind the dam, while the light silt washes over the dam. Within one to four rainy seasons, the dam fills with sand. But, up to 40 percent of the volume behind the dam is water, trapped between sand
76
UNCCD . World Bank
