In what condition of the flow over a weir can it be considered as free and submerged?

In a free weir flow system, the discharge of the flow over the weir isn’t dependent on downstream conditions. The nappe of the weir would discharge into the air. Put simply, a weir is free flowing when the water level downstream is lower than the lowest point of the weir’s crest.

What are the effects of end contraction of weir?

If the weir width is less than the width of the channel, it is known as weir with end contractions. The end contraction results into the decrease of the width of neppe.

What is the function of weir?

A weir /wɪər/ 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.

What is free flow and submerged flow?

A free flow also induces a hydraulic jump downstream of the flume. Submerged flow: When the water surface downstream of the flume is high enough to restrict flow through a flume, submerged flume conditions exist. A backwater buildup effect occurs in a submerged flume.

What is submerged flow condition?

Submerged (or drowned) flow occurs when the water surface downstream from the flume is high enough to reduce flow through a flume.

What is the difference between weir and notch?

Basically there is no difference between a notch and a weir, except that a notch is of small size while a weir is of large size. A notch is usually made of metal plate whereas a weir is made of masonry or concrete. The bottom edge over which the water flows is called the sill or the crest of water the notch.

Why does weir have a contraction?

For weirs where the notch does not span the full channel, the flow on sides of the channel must turn to pass through the notch opening. This turning and acceleration results in a curved flow path or side contraction allowing the water to spring clear of the notch opening.

What is meant by end contraction affect in notches and weirs?

End Contraction: The horizontal distance from the ends of the weir crest to the sides of the weir pond. Weir Scale or Gauge: The scale fastened on the sides of the weir or on a stake in the weir pond to measure the head on the weir crest. Nappe: The sheet of water which overflows a weir is called a nappe.

What is another word for weir?

What is another word for weir?

barrier wall
dam barrage
levee dike
embankment obstruction
gate bank