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Current page: Home > what we do > sand dams To watch our film on sand dams click here. Sand Dams
Despite having been built successfully in Africa, Asia and South America for at least the last fifty years, they are still an under-utilised solution for providing clean water and improving the environment.
What is a Sand Dam? A sand dam is a reinforced concrete wall built across seasonal river beds - 2 to 4 metres high and up to 90 metres across. A pipe is built into the dam, going 20 metres upstream. Over one to three seasons, the dam fills up with water, then sand, which filters water through the pipe built into the dam. About 40% of the volume behind the dam is water, meaning that sand dams can hold an incredible 2 to 10 million litres of water! Water is collected either from the pipe on the lower side of the dam, or by digging holes in the sand behind the dam to access the water. Each dam provides a clean water supply for up to 1,200 people, animals and nurseries for trees and vegetables. Furthermore, the effect of improving water availability in a 20km radius means that a sand dam may indirectly benefit up to 100,000 people. "I love the dams more than anything, because they came out of nowhere. We have created our own springs for our own people." Joshua Mukusya, Founder What are the benefits of Sand Dams?
The benefits of sand dams are staggering, impacting on health, education, food supply and much more. A dam provides a year-round source of water so people do not have to spend long back-breaking hours during the drought season collecting water from far away. Children go to school more often - not just because they don't collect water themselves, but because they don't have to stay at home looking after children whilst their mother takes 8 hours to collect just 20 litres of water. Time saved means more time can be spent on other activities, such as growing food - vital for life and for income to pay school fees. "The dams enable us to save our time, and that enables us to do much more work on our farms than before." Rhoda Mutio Silu of the Utooni Development Project The water is also much cleaner, having been filtered through the sand and protected from parasites, so children are less likely to get ill. Instances of typhoid and diarrhoea are virtually eliminated. A sand dam also transforms the environment, as its presence raises the water table level both upstream and downstream of the dam. This increases the tree survival rate and allows other crops to grow that would not normally survive. More trees and plants means more food for humans and animals, increasing overall biodiversity and making it possible for people to create a sustainable livelihood in harmony with their environments. How is a Sand Dam built?
Africa is scattered with washed away dams, but our co-founder, Joshua Mukusya, has built over 450 dams, none of which has washed away.
Excellent Development only builds dams where communities want them - demonstrated by their willingness to collect all the water, sand and stones required for construction. This amounts to 50% of the total cost. The communities build them too, so because they own the dams, they take great pride in the benefits they bring. Terracing the land around the dams improves their effectiveness and very little maintenance is required. After the best site is chosen, the craftsmen employed by Excellent Development construct a timber frame as the basis for the dam. The frame is filled with stones collected by the community group members, along with cement to set the structure and barbed wire for reinforcement. The cement is mixed on the ground using shovels, and passed along a line of people to reach the dam. This goes on until the dam is full with cement. Community groups from different areas often come to help their neighbours build dams. This is part of the Kamba tribe's tradition of Mwethya where people work together to achieve great things. When the Kola community self help group built an extension to their dam in 2004, an amazing nine community groups came from as far as 30km away to help out! To watch our film on sand dams click here. |
Sand dams are a cost-effective, innovative solution to water shortages in semi-arid areas, which also transform environments beyond recognition.
