Kitui & Makueni Sand Dams — Kenya's Drought Water Harvesting, With Mixed Independent Evidence (Cautionary Case)

Sand dams are concrete walls built across ephemeral streams on bedrock; sand accumulates behind them during seasonal floods and stores water in its pore space, protected from evaporation. Ukambani in south-eastern Kenya (Kitui, Machakos, Makueni) is their epicentre, with several thousand built by NGOs such as SASOL (Sahelian Solutions Foundation) and the Utooni Development Organization. This entry records the independent evidence honestly, as a cautionary case.
Neufeld et al. (Journal of Arid Environments, 2021) assessed a representative sample of 97 dams drawn from SASOL and UDO lists. Most were filled with water-holding sediment (median 25% siltation-related capacity loss), and water was present in over half of sediment cores at 57% of dams. But satellite analysis found no average increase in greenness or moisture versus control sites, only 43% of dams showed active water harvesting and only 39% had adjacent agriculture; benefits were understood by communities but less often realised.
Ngugi et al. (Sustainable Water Resources Management, 2020) surveyed 116 dams in Kitui County's Tiva catchment in October 2016 and found roughly half had no water at the time of assessment, even at sites meeting recommended criteria; only rainfall, soil clay content and stream order showed consistent influence. They call for better siting guidelines. Programme reports by Just a Drop and the Africa Sand Dam Foundation (650+ households surveyed 2018–2024) report wider social benefits but are not independent evaluations. Lesson: sand dams can work, but siting and post-construction use determine whether water access actually improves.

Read the full analysis: https://emu.edu/academics/academic-and-creative-excellence/docs/2021_general/Neufeld%20Assessment%20of%20water%20presence.pdf