A comprehensive study led by the University of Oxford has provided conclusive evidence that sand dams, a low-tech water harvesting technique, are highly effective in recharging groundwater and transforming water security in Kenya’s Arid and Semi-Arid Lands (ASALs). The research, conducted over several years in counties like Kitui and Makueni, demonstrates that these simple structures—concrete walls built across seasonal sandy rivers—not only capture and store surface water but also actively replenish underground aquifers. During seasonal rains, the dam captures silt and sand, which then acts as a massive natural reservoir, storing millions of litres of water that slowly percolates into the surrounding ground, raising the water table and providing a perennial source of clean water for communities and ecosystems long after the rains have ended.
The impact of this proven technology is transformative for the resilience of rural communities. Before the construction of sand dams, families in these regions, often women and girls, would spend hours each day trekking to distant and often contaminated water sources during dry seasons. Now, with the elevated water table, they can access water from shallow wells dug into the riverbank sand, sometimes just a short walk from their homes. This reliable access has a cascading effect, enabling small-scale irrigation for kitchen gardens, improving nutrition and household income, and freeing up time for children to attend school and for women to engage in other economic activities. The study confirmed that areas with sand dams showed a significantly higher and more stable water table compared to control areas without them.
The long-term implications of this research are significant for climate adaptation policy across the Horn of Africa. Sand dams represent one of the most cost-effective and sustainable solutions to water scarcity in dryland regions. Their success provides a powerful evidence base for governments and development partners to scale up investment in this nature-based infrastructure. As climate change intensifies drought cycles, the strategic widespread implementation of sand dams could shield millions of people from the worst impacts of water stress, reducing vulnerability and conflict over resources. This simple, community-owned technology stands as a proven bulwark against desertification, offering a scalable blueprint for building water resilience in some of the world’s most climate-vulnerable landscapes.