African sustainable development charity, Excellent Development, is marking World Water Day by celebrating having built 100 small-scale sand dams in semi-arid Kenya since 2003, which are providing clean water to over 100,000 people.

The charity works with Kenyan community groups who are pioneering the innovative technology of sand dams to combat the pressures of drought, deforestation and climate change in semi-arid Africa. Their triple approach to conserving soil and water by building sand dams, digging terraces and planting trees transforms the micro-climate by permanently increasing the water table and creating the environment for increased food production.

Sand dams, which are essentially reinforced concrete walls built across seasonal river beds, retain water below the sand that collects behind them. They provide a clean water supply during the dry season as well as avoiding the evaporation and malaria risk of conventional open-water dams. Even though total rainfall in the area is between 600 and 1,200 mm, the concentrated rainy seasons mean that very little is retained and local springs soon dry up - meaning women walk 5-10 km for water during the dry season and up to 20km during droughts.

Rhoda Silu is a member of the Utooni Development Project, a self-help group that was the original inspiration for Excellent Development. She explains: "The dams enable us to save our time, and that enables us to do much more work on our farms than before, which helps us earn money from vegetables and increased production of staple crops."

She adds, "Diarrhoea, a major child killer, has reduced by 95% in our area due to the clean water from sand dams. So many children now attend school regularly because their mothers don't need them to look after the home whilst they collect water."

Sand dams hold an incredible 2-10 million litres of water - recharged after each rainfall. All the dams are built using local materials at carefully selected points in seasonal riverbeds. Local people collect all the sand, stones and water required for the construction and work together to build the dam, which can reach up to 5 metres high and 60 metres across. Often several villages come together to help each other achieve this, so committed are they to the long term benefits it will bring.

The dams improve water capacity so that tree and vegetable nurseries can be started, and the terracing of fields reduces soil erosion and increases the amount of rain water absorbed. This increases and diversifies food production for people and livestock. Farmers are then able to generate income by selling surplus produce, which is often spent on school fees for their children.

Joshua Mukusya, the co-founder of Excellent Development has worked for over 28 years to help communities improve their water supplies. He says: "I love the dams more than anything, because they came out of nowhere. We have created our own springs for our own people"

Simon Maddrell, co-founder of the charity, comments: "Sand dams are the most cost-effective method known for providing clean water, however they aren't as sexy as water tanks or water pumps and are a vastly under-utilised technology as a result."

Simon adds, "We are delighted to be celebrating our 100th dam built and it is our hope that more and more people will learn of their benefits in combating the impacts of climate change and improving water supplies and food production in semi-arid areas."