What is a weir in civil engineering?
A weir is a concrete or masonry structure which is constructed across the open channel (such as a river) to change its water flow characteristics. Weirs are constructed as an obstruction to flow of water. These are commonly used to measure the volumetric rate of water flow, prevent flooding and make rivers navigable.
How many types of weirs are?
How many types of weirs are there based on the shape of the crest? Explanation: The four types are sharp-crested, broad-crested, narrow-crested and ogee-shaped weir.
Why are there weirs on rivers?
A weir is a small dam built across a body of water, such as a river. We use them to help control the flow of water. Weirs can help raise the water level so that boats can pass through, and they can also reduce the flow of water to prevent flooding.
What is a weir used for?
A weir is a small barrier built across a stream or river to raise the water level slightly on the upstream side; essentially a small-scale dam. Weirs allow water to pool behind them, while allowing water to flow steadily over top of the weir.
What are weirs what are they used for?
Weirs and flumes make excellent flow-measuring devices because they have a one-to-one relationship between discharge and stage. A weir is an overflow structure placed across the flow. The edge over which the flow occurs is called the crest of the weir.
What are weirs used for?
Why are weirs used?
Commonly, weirs are used to prevent flooding, measure water discharge, and help render rivers more navigable by boat. In some locations, the terms dam and weir are synonymous, but normally there is a clear distinction made between the structures.
What is weir in irrigation engineering?
Weir is a low obstruction that is built across a river or canal to raise the water level, or in parallel to divert the water. The in-stream weirs are widely used to measure the rate of flow. At flow rates above the threshold flow rate the water level rises above the level of the diversion weir and water is diverted.
What is a weir structure?
By definition, a weir is a man-made structure designed to alter a river’s flow characteristics and measure flow rates. A weir is a low lying barrier similar to a dam, but instead of stopping water significantly, it uses its structure to slow down or manipulate water flow for various purposes.
Why We Use weir in the channels?
Weirs allow water to be routed through a structure of known dimensions, permitting flow rates to be measured as a function of depth of flow through the structure. Thus, one of the simplest and most accurate methods of measuring water flow in open channels is by the use of weirs.
What is a weir in a canal?
From Wikipedia, the free encyclopedia. A waste weir on a navigable canal is a slatted gate on each canal level or pound, to remove excess water and to drain the canal for repairs or for the winter shutdown.
What is a weir and how does it work?
Weirs have been used for ages to control the flow of water in streams, rivers, and other water bodies. Unlike large dams which create reservoirs, the goal of building a weir across a river isn’t to create storage, but only to gain some control over the water level.
What is a weir dam?
A weir, also known as a low-head dam is a small overflow-type dam commonly used to raise the level of a river or stream. Weirs have traditionally been used to create mill ponds in such places. Water flows over the top of a weir, although some weirs have sluice gates, which release water at a level below the top of the weir.
Which type of Weir is used to measure discharge?
The shape of the weir is actually reverse triangle like V. so, it is also called V-notch weir. This type of weirs are well suitable for measuring discharge over small flows with greater accuracy. Here also consider an elementary horizontal strip of water of thickness dh at a depth h from the water surface.
What is the purpose of a sharp crested weir?
Sharp-crested weirs are useful only as a means of meas- uring flowing water. In contrast, weirs not sharp crested are commonly incorporated into hydraulic structures as control or regulation devices, with measurement of flow as their secondary function. FLOW OVER WEIRS.