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According to the World Commission on Dams, a key difference between a dam and a barrage is that a dam is built for water storage in a reservoir, which raises the level of water significantly. A barrage is built for diverting water, and raises the water level by only a few feet.
A saddle dam is an auxiliary dam constructed to confine the reservoir created by a primary dam either to permit a higher water elevation and storage or to limit the extent of a reservoir for increased efficiency. An auxiliary dam is constructed in a low spot or "saddle" through which the reservoir would otherwise escape.
Dam: A dam is a barrier that stops or restricts the flow of surface water or underground streams, or water reservoir resulting from placing such a structure. Delta: the location where a river flows into an ocean, sea, estuary, lake, or reservoir. Distributary or distributary channel: a stream that branches off and flows away from the main ...
A good example is the Honor Oak Reservoir in London, constructed between 1901 and 1909. When it was completed it was said to be the largest brick built underground reservoir in the world [12] and it is still one of the largest in Europe. [13] This reservoir now forms part of the southern extension of the Thames Water Ring Main. The top of the ...
The flushing flow method involves partially or completely emptying the reservoir behind a dam to erode the sediment stored on the bottom and transport it downstream. [7] [6] Flushing flows aim to restore natural water and sediment fluxes in the river downstream of the dam, however the flushing flow method is less costly compared to removing dams or constructing bypass tunnels.
Since there is only an extremely low flow within the reservoir so no water level gradient, the head can be clearly seen: where the farthest watercourse discharges into the reservoir. Upstream of the actual reservoir is likely to be a pre-dam, which typically have a constant water level so the head is reinforced.
The general design for a flood detention dam has a cross sectional shape of a trapezoid, where the longer of the parallel sides is the base of the dam, and the angled sides face upstream and downstream. The flood detention dam has an opening at the top to release the flood water at a controlled rate that the channels below can accommodate.
In many cases, the water that comes out of the dam originates from the bottom of the reservoir created by the impoundment. The resulting dam discharge is relatively cold compared to the natural temperature of waterway due to the stratification of water that occurs in reservoirs. [ 7 ]