What are Sand Dams?

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Short film on the miracle of Sand Dams (1:16).

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Sand Dams are the most cost-effective form of rainwater harvesting in drylands.
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A Sand Dam is a reinforced rubble stone masonry wall built across a seasonal sandy riverbed.

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A Sand Dam is a reinforced rubble stone masonry wall built across a seasonal sandy riverbed.

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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.

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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.

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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.

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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.

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Sand Dams permanently raise the water table, making water easily accessible from traditional scoop holes all year round.

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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.

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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)

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