What are Sand Dams?
Short film on the miracle of Sand Dams (1:16).
A Sand Dam is a reinforced rubble stone masonry wall built across a seasonal sandy riverbed.
A Sand Dam is a reinforced rubble stone masonry wall built across a seasonal sandy riverbed.
During the rainy season, a seasonal river forms and carries soil (made up of sand and silt) downstream. The heavy sand accumulates behind the dam, while the light silt washes over the dam wall.
During the rainy season, a seasonal river forms and carries soil (made up of sand and silt) downstream. The heavy sand accumulates behind the dam, while the light silt washes over the dam wall.
Within one to four rainy seasons, the dam completely fills with sand. However, up to 40% of the volume held behind the Sand Dam is water, stored between the sand particles.
Within one to four rainy seasons, the dam completely fills with sand. However, up to 40% of the volume held behind the Sand Dam is water, stored between the sand particles.
Sand Dams permanently raise the water table, making water easily accessible from traditional scoop holes all year round.
Pipes built into the Sand Dam wall, and connected to an infiltration gallery, provide water 'on-tap' close to people's homes. Often, the pipes are connected to a tank which allows water to be pumped out for irrigation.
A hand pump on a sealed shallow well that is connected, via an infiltration gallery, to a Sand Dam.
Find out more about sand dams and how how they are built (7:45)
What are Sand Dams?
Sand Dams are the most cost-effective form of rainwater harvesting and provide communities with a clean, local and reliable source of water – even during periods of drought.
Sand Dams store up to 20 million litres of water and provide a year-round supply for up to 1,000 people – with virtually zero operation and maintenance costs. Sand Dams store water under sand, protecting it from contamination and evaporation – cleaner water that lasts longer.
Sand Dams save people up to 8 hours a day because they provide water to families an average of only 30 minutes from home. Communities are then able to invest this time in protecting their land from erosion and investing in climate smart agriculture.
What exactly is a Sand Dam?
A Sand Dam is a steel reinforced concrete (or technically speaking, rubble stone masonry) wall built across a seasonal sandy riverbed. During the rainy season, a seasonal river forms and carries soil (made up of sand and silt) downstream. The heavy sand accumulates behind the dam, whilst the lighter silt washes downstream over the dam wall. Within one to four rainy seasons the dam completely fills with sand. However, up to 40% of the volume held behind the dam is actually water stored between the sand particles. The water can be abstracted from the sand dam in three main ways: Traditional scoop holes; an infiltration gallery either leading a tank behind the dam and/or piped through the dam leading to a tap; an infiltration gallery leading to a sealed shallow well in the valley side – topped with a hand pump.
Sand Dams are not only cost-effective but last at least 30-50 years and along with the virtually zero operation and maintenance costs make them a remarkably low-cost, sustainable solution to rural water supply.
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At Excellent Development we are passionate about Sand Dams because we know the remarkable impact that they have on people, the environment and even animals. That's why we are determined to promote Sand Dams as 'the best thing since sliced bread!'
Simon Maddrell, Executive Director, Excellent Development.
Read about our work pioneering Sand Dams.
Download our Sand Dam brochure
