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Many pathways of water can enter through a dam structure to produce a well-defined nappe. However, engineers classify dams as either overflow dams, where water consistently flows over or is blocked through a gate on top of crest, or non-overflow dams, which channel water through or around the dam with emergency floodgates.
A fishing weir, fish weir, fishgarth [1] or kiddle [2] is an obstruction placed in tidal waters, or wholly or partially across a river, to direct the passage of, or trap fish. A weir may be used to trap marine fish in the intertidal zone as the tide recedes, fish such as salmon as they attempt to swim upstream to breed in a river, or eels as ...
A weir / w ɪər / or low-head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of lakes, ponds, and reservoirs.
This involved the construction of weirs in order to divert water into the mills. The weirs, however, presented an obstacle to navigation and to solve this problem locks were built alongside the weirs to enable boats to be moved between levels. Originally these were flash locks that were essentially removable sections of weir. A boat moving ...
Hydraulic jump in a rectangular channel, also known as classical jump, is a natural phenomenon that occurs whenever flow changes from supercritical to subcritical flow. In this transition, the water surface rises abruptly, surface rollers are formed, intense mixing occurs, air is entrained, and often a large amount of energy is dissipated.
The weir has adversely impacted on the cultural integrity of the fish traps and on the ecology of the river. The weir, and the fishway that was included in the original construction, also changed the flow pattern through the traps. The weir evenly distributed flow across the river where beforehand it followed a channel near the south-east bank.
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A drop structure, also known as a grade control, sill, or weir, is a manmade structure, typically small and built on minor streams, or as part of a dam's spillway, to pass water to a lower elevation while controlling the energy and velocity of the water as it passes over.