What is wier?

A weir is a barrier across a river or stream designed to alter the flow characteristics of water. In most cases, weirs take the form of a small dam, resulting in a pool of water behind it.

• Function: Weirs primarily serve to raise the water level upstream. This can be for several purposes, including:

  • Water%20diversion: Diverting water into irrigation channels or for other uses.
  • Flow%20measurement: Providing a consistent and predictable flow rate over the weir, allowing for accurate measurement of water flow.
  • Flood%20control: Acting as a barrier to slow down the flow of water and reduce the risk of flooding.
  • Navigation: Creating deeper water levels for boat traffic.

• Types: Weirs are classified based on their shape and flow characteristics:

  • Sharp-crested weirs: These weirs have a thin, sharp edge, causing the water to spring clear of the weir.
  • Broad-crested weirs: These weirs have a wider, flat top, allowing the water to flow smoothly over the weir.
  • Ogee%20weirs: These weirs have a curved profile, often used in spillways of dams.
  • V-notch%20weirs: These weirs have a V-shaped notch, used for measuring small flow rates.

• Environmental Concerns: Weirs can have negative environmental impacts, such as:

  • Fish%20migration%20barriers: Blocking the movement of fish and other aquatic life.
  • Sediment%20accumulation: Trapping sediment upstream, leading to changes in river morphology.
  • Water%20quality%20changes: Altering water temperature, oxygen levels, and other water quality parameters.

• Construction: Weirs are typically constructed from concrete, steel, or timber. The design and construction of a weir must consider factors such as the flow rate of the river, the stability of the surrounding banks, and the potential for erosion.