Development Ratings

The sand dam concept can only be applied in semi-arid regions where there is sufficient soil sand content. The community members carry out the work themselves, and if they do not participate, then the dam does not get built. In the focus area in Eastern Kenya, the Kamba people’s tradition is one of cooperation and participation. Rocks and sand (collected by the community) along with cement and steel in a timber frame are used to build a retaining wall across the bed of a river. Once the dam has been built, the rain-fed river water is retained behind it as in a normal dam. However, due to the sand content of the soil, sand is deposited behind the wall over a period of 1 to 3 seasons, filling the area behind the dam wall. The sand-filled area, which is now compacted enough to walk on, retains enormous quantities of water, mixed in a sand:water ratio of 60%:40%. Water is recovered through run-off pipes on the downstream side of the dam or by digging into the sand to expose the new water table level. Once held in the sand, the water will not sustain parasite or mosquito larval growth, will not suffer from animal contamination, will raise the surrounding water table, and will be filtered clean by the sand. Evaporation from a sand dam is negligible.

In exchange for the dam design assistance, the communities dig terraces for trees, crops, and soil and water retention. The third activity is the growing and planting of trees, particularly endangered indigenous species that are often relied on for traditional medicines. Trees change the micro-climate which attracts rain, birds, insects and small mammals (and therefore animal-distributed seeds). They also increase shade, bind soil, and provide food and cash crops from fruit, seeds and leaves. More trees planted locally means that firewood is more easily collected without the previous levels of deforestation. An additional activity is the construction of water tanks, particularly in school compounds which encourages school attendance and protects child health.

Excellent Development’s mission is ‘development that doesn’t cost the earth’. The dams are small-scale to support the local communities: they have negligible up-front negative ecological impact. The longer-term positive environmental effects of the programme on the immediate area are clear, not to mention the income and health improvements of the directly and indirectly benefited communities.

Excellent Development launched three TreeDuty brands (CO2 offsetting) during 2008, for flights, vehicles and annual offsets. It plans the development of the WaterRelief and TreeRelief brands. dcarbon8 (a carbon measurement & reduction consultancy) uses the projects as CSR projects for its clients. Other partners include Travel Counsellors (offering flight offsets), travel agents, oneworld.net, and media and botanical organisations.