Reservoirs - Below Ground

Small sunken household reservoirs may be used as storage dams, which are filled up by rain water that is channeled towards a strategically placed inlet. This provides approximately four months of water into the dry season for households that are dependent on irrigation for their crops.

Place : Tshikonelo, Limpopo, South Africa - Client : Department of Water Affairs & Forestry (DWAF) / Rain Water Harvesting Pilot Programme. Designed and built by Dams for Africa, October 2006

(1) A lockable trap door gives access to the sunken reservoir. The inlet incorporates a small 'stilling basin' which limits the amount of sediment going into the tank.

(2) An embankment is formed on one side of the dam to channel run-off rain water to the inlet of the reservoir.

(3) Mrs Matshekwa's rain water harvesting 'dam'. The inlet has a small stilling basin to prevent sediment from going
into the tank.

(4) Mrs Mutshavhini Munyai and Mr Calvin Netshivhodza admire her rain water harvesting 'dam'. It clearly shows the outlet from where water is channelled to the garden.

(5) Precast concrete blocks are used in the construction of this sunken household reservoir. An arm rotating from a central pole enables the builders to construct a perfect cylinder.

(6) A travelling mould, or 'Finnbuilder', is used to construct the wall - a sand-cement mixture is moulded. Note that a rotating arm is again used to achieve a perfect cylinder.

(7)A water proof coating is used to prevent water seeping out of the tank through the walls.

(7)Alternatively the tank could be lined with a plastic liner to make the sunken reservoir water proof, as is the case with this dam.

(8)Yet another way of water proofing is to give the walls of the tank a coat of superlaykold to prevent water seepage.

(9) The stilling basin at the inlet that prevents sediment from going into the tank is clearly shown in this picture, as well as the trap door that gives access to the sunken reservoir.

(10) Aided by her Rain Water Harvesting 'dam', Mrs Mutshavhini Munyai is looking forward to feeding her family healthy, home-grown vegetables and intends to sell the surplus to the community.