What is the breadth of a weir?

What is the breadth of a weir?

The weir breadth is the same as the channel width. The weir surfaces are of planed wood or smooth concrete. The downstream nappe is fully aerated, and the weir entrance is square. The profile for the second weir form is shown in figure 26.

What is weir crest length?

Solution. In equation 5.42 in the FlowMaster help “Broad-Crested Weir”, “L” is defined as the ‘Length of Roadway Crest’, which is the distance perpendicular to the flow direction. This is the value that you’d enter as your “Crest Length” in the Broad Crested Weir worksheet.

What is the broad crested weir?

The broad crested weirs are a hydraulic structures widely used for depth control and flow measurement in field and laboratory canals . The geometry described as a flat-crested structure with a length (L) of crest large enough compared to the flow thickness over the crest of the weir.

What is an outlet weir?

A weir is usually modeled as an outlet device that controls the discharge from a pond. HydroCAD provides numerous weir options, as shown at the right. Discharge equations and other details for each type of weir are provided in the Reference Manual and the help system.

What is ogee shaped weir?

ABSTRACT. The shape of an ogee spillway is based on the shape of the lower nappe of water flowing over an aerated sharp-crested weir. At the design discharge, this shape minimises the possibility of sub-atmospheric pressure occurring on the spillway and maximises the discharge across the spillway.

What is ogee crest?

An ogee crest is a common control structure shape for sewice spillways, including morning glory inlets, side channel inlets, and controlled and uncontrolled overfall chutes. Consequently, the ogee crest has received much attention by researchers and its hydraulic characteristics are well understood.

What is a weir in a canal?

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.

How does a weir measure flow?

Weirs to Measure Flow It works by raising the water level upstream of the weir, and then forcing the water to spill over. The more water is flowing over the weir, the deeper the water will be upstream of the weir. So measuring flow rate (CFS) can be done by simply measuring the depth of the water upstream.

What is narrow crested weir?

Narrow-crested weir: It is similar to rectangular weir with a narrow shaped crest at the top. The discharge over the narrow crested weir is similar to discharge over the rectangular weir. 4. Ogee-shaped weir: Generally ogee shaped weirs are provided for the spillway of a storage dam.

How do you get out of a weir?

Water falls over the weir, drives to the bottom of the riverbed, bounces back up and then rejoins the downward flow at the top. These circulating stoppers can be aggressive and impossible to escape. You can try to swim down or sideways to and exit the circuit, and then rise to the surface.

What are some disadvantages of a weir?

Disadvantages of Weirs

  • Spacious Upstream Weir Pool Required.
  • Cold Weather Can Compromise Readings.
  • Discharge Must Be Free-Spilling.
  • Weir Maintenance Is Extensive.
  • Weirs and Flumes From Tracom.

What is HydroCAD?

HydroCADis a Computer Aided Design tool used by Civil Engineersfor modeling stormwater runoff. HydroCAD provides a wide range of commonly used hydrology and hydraulicscapabilities including: SCS, NRCS, and SBUH runoff hydrology Rational Method with automatic IDF curves Use local rainfall data or the built-in rainfall library

What is the difference between crest breadth (LR) vs crest length (L) in Flowmaster?

What is the difference between crest breadth (Lr) vs. the Crest Length (L) for a broad crested weir in FlowMaster? In equation 5.42 in the FlowMaster help “Broad-Crested Weir”, “L” is defined as the ‘Length of Roadway Crest’, which is the distance perpendicular to the flow direction.

What’s new in hydrocad-10?

Many new outlet devices were added in HydroCAD-10, including tubes, siphons, asymmetrical weirs, constant-flow devices (such as floating weirs), and even a progressive dam breach. Update details here.

When is the broad-crested weir used?

In general, the broad-crested weir capability is useful only in cases where the discharge coefficient varies with head . If the coefficient is relatively constant, nothing is gained by using the (more complex) broad-crested weir technique.