Weir equation

How do you calculate flow through a weir?

The equation recommended by the Bureau of Reclamation in their Water Measurement Manual, for use with a suppressed rectangular weir is: Q = 3.33 B H3/2, where Q is the water flow rate in ft3/sec, B is the length of the weir (and the channel width) in ft, and H is the head over the weir in ft.

How is weir height calculated?

There should be air (not trapped) underneath the water leaving the weir. The Length is the bottom width of the weir. The height is measured from the bottom of the weir opening to the top of the water level ponded behind the weir (not the water level right as it leaves the weir).

What is a weir used for?

Weirs are fixed barriers across a river or stream that force water to flow over their tops, where the height of the water above the weir can be used to calculate flow.

Why is a weir dangerous?

In strong currents a swimmer can find they are pushed against roots or the bank, and the water holds them against it, and they can’t get away: the weight of the water holds them there. ‘ In a weir you could be placing yourself under a weight of water, which in a way is dangerous.

How does Weir work?

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. In a weir, the surface over which the water flows is known as the crest.

What are the different types of Weir?

Weirs are classified according to:Types of Weirs based on Shape of the Opening. Rectangular weir. Triangular weir. Trapezoidal weir.Types of Weirs based on Shape of the Crest. Sharp-crested weir. Broad- crested weir. Narrow-crested weir. Ogee-shaped weir.Types of weirs based on Effect of the sides on the emerging nappe.

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What is rectangular Weir?

[rek′taŋ·gyə·lər ′wer] (civil engineering) A weir with a rectangular notch at top for measurement of water flow in open channels; it is simple, easy to make, accurate, and popular.

How Do You Measure V notch weir?

V Notch Weir Equation for Notch Angle Other than 90 Degrees of Reclamation, Water Measurement Manual, should be used. That equation is: Q = 4.28 Ce Tan(θ/2)(H + k)5/2, where Q and H are as previously defined, θ is the angle of the v notch, Ce is the effective discharge coefficient, and k is a head correction factor.

What is Francis formula?

[′fran·səs ‚fȯr·myə·lə] (fluid mechanics) An equation for the calculation of water flow rate over a rectangular weir in terms of length and head.

What Weir means?

(Entry 1 of 2) 1 : a fence or enclosure set in a waterway for taking fish. 2 : a dam in a stream or river to raise the water level or divert its flow.

Is Weir a Scrabble word?

WEIR is a valid scrabble word.

Are weirs man made?

A weir is a man-made structure designed to alter a river’s flow characteristics and measure flow rates. Weirs are man-made structures and are therefore put into an existing lake.

Can you swim in a weir?

Weirs are generally to be avoided – some types in particular (box weirs) are fatal to trapped swimmers and kayakers. In some places you will see people swimming happily upstream in the pools formed by weirs (their purpose is to deepen the water), that’s probably safe in low flows.

What is a weir for a pool?

A weir is a type of barrier across a river that is created to adjust or alter its flow. With this in mind, a weir for a swimming pool is a barrier in a skimmer over which water flows. A floating weir raises and lowers its level to match the water level in a pool or spa.

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