Sand dams' bank water for dry season in semi-arid Kenya

Isaiah Esipisu in AlertNet: Barely a month after heavy rains pounded Kenya, many seasonal rivers in the country’s semi-arid east are already drying up, and residents are preparing for the months-long dry season.

But some, like Paul Masila and other members of  the Woni Wa Mbee self-help group, are not worried about the looming dry spell. Instead, they are preparing to plant crops or are harvesting fields they planted before the rains.

The group – the name means “progressive vision” in Kamba, the local langage – have revolutionised the region’s fortunes by finding a way to store millions of litres of water under the bed of the Kaiti River, providing the once-parched community with water for domestic use and irrigation throughout the year. “Drought will never again be a problem, particularly for future generations,” said Titus Mwendo, a 31-year-old farmer in Miambwani, in the Eastern region’s Makueni County.

.... Woni Wa Mbee and other self-help groups in the area, aided by local non-governmental organisations, have found a way to trap and store the Kaiti’s water in its own sandy riverbed, keeping water available for months after the river has disappeared.

“The water reservoirs are called sand dams,” said Kevin Muneene, chief executive officer of the Utooni Development Organisation, one of the supporting NGOs. Over the past two years, the organisation has helped 80 self-help groups construct 1,528 sand dams in arid and semi-arid areas of Kenya’s Rift Valley and Eastern region.

To make a dam, he said, a high concrete barrier is constructed across a seasonal river. When it rains, the water carries sand downstream, depositing it up to the level of the barrier. When the rains finish, water remains trapped in the piled-up sand for up to a kilometre upstream of the dam, depending on the dam’s height. “A well-constructed sand dam has 60 percent of its volume as sand, while the remaining 40 percent is always water,” said Muneene, an expert in sand dam construction....

Sand dam illustration by Iangrahamneal, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license