What is a long crested weir?

The purpose of long crested weir is to provide more. maintaining of ground water levels. Typically long crested. weir crest length than the one which is possible with a. weirs allow the increase in water depths for navigation or.

How wide is a broad crested weir?

A broad-crested weir is to be designed to operate with critical flow above its crest and no downstream control. The maximum discharge capacity will be 135 m3/s. The weir crest will be 2.5 m above the natural channel bed and its width will be 15 m. (Assume the channel to be prismatic, smooth and rectangular.)

What is the difference between sharp crested weir and broad crested weir?

The sharp crested weir will help in measuring the discharge of the water from the small rivers and canals and the weir is placed in the direction of the flow of water. The broad crested weir is one which the water flow discharge in measured from large water bodies like big canals.

Does the length of weir affect the discharge coefficient?

Broad-crested weirs (BCW) are often used in hydraulic engineering and water management. The most complex factor that affects the discharge capacity of BCW is the discharge coefficient. Discharge characteristics of weirs of finite crest length with upstream and downstream ramps.

What is weir and its types?

Types of Weirs based on Shape of the Crest Sharp-crested weir. Broad- crested weir. Narrow-crested weir. Ogee-shaped weir.

What is narrow crested weir?

Narrow-crested weir: It is similar to rectangular weir with narrow shaped crest at the top. The discharge over narrow crested weir is similar to discharge over rectangular weir.

What is the effect of end contraction on the discharge through a 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.

How is weir discharge coefficient calculated?

The generalized weir equation can be written as Q = C D C V C S C P C b l g b h 1.5 where CD is a discharge coefficient, Cv is the velocity coefficient, both as defined before, Cs is a shape coefficient depending on the lateral shape of the crest (e.g. shallow ‘Vee’), Cp is a coefficient to take into account the height …

What is end contraction of weir?

An end contraction is when the length of the weir (L) is less than the width of the Channel and a nappe contracts either one or both sides of the weir.

What is weir and types of weir?

What is a sharp crested weir?

A weir is a barrier in an open channel, over which water flows. A weir with a sharp upstream corner or edge such that the water springs clear of the crest is a “sharp crested weir”. All other weirs are classified as “weirs not sharp crested”. Weirs are to be evaluated using the following equation: Q = CLH 3/2

What is the maximum discharge capacity of a broad crest Weir?

A broad-crested weir is to be designed to operate with critical flow above its crest and no downstream control. The maximum discharge capacity will be 135 m3 /s. The weir crest will be 2.5 m above the natural channel bed and its width will be 15 m. (Assume the channel to be prismatic, smooth and rectangular.)

What are the general weir design requirements?

To ensure accurate discharge measurement, the following general weir design requirements apply to all types: The weir should consist of a thin plate 1/8 to 1/4 inch (3 to 6 mm) thick with a straight edge or a thicker plate with downstream chamfered edge.

What are the characteristics of a weir?

The crest of a weir may be sharp (metal plates) or broad (small dams or humps). If the overflow from the weir is unobstructed by the water level downstream from the weir, a free overfall is said to exist. If the weir overflow is partially under water, the weir is termed submerged and a unique stage discharge relationship may no longer exist.