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Water Portal / Rainwater Harvesting / Groundwater recharge / Sand dam

194 bytes added, 21:53, 30 March 2012

→‎Building the sand dam (and wing wall)

====Building the sand dam (and wing wall)====

[[Image:SandDamConstruction.JPG|thumb|right|200px|Sand dam under construction. Somaliland. Eric Fewster, BushProof / Caritas]]

* Timing is important: dams should be built during the dry season, but don’t build dams too close to the rains in order to avoid the trench filling up with water or the dam being washed away.

* The method depends on the type of dam and the type of ground. The construction of sand dams in cascades improves total storage and efficiency and minimizes seepage losses. Dams made of concrete, stone-masonry (cheapest and easiest) and brickwork require skilled labour for construction, but are stronger and have a longer lifespan.

* Usually sand dams are built onto a rock layer, but where there is no rock and only clay, it can still work but as long as the foundation is keyed into the clay layer and where the wall does not protrude more than 0.5m above original sand level, otherwise there is a risk the structure overturns during a flood event.

Winona

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