Weir (Water Overlay)

Weirs are effectively small dams in the water, and allow water to flow from a water body with a higher water level to a lower water level. Any water exceeding the height of the weir can flow over it, increasing the throughput as the water level increases. Strictly, water can flow over the weir in either direction.

A weir is a line-based building.

Icon	Key	Unit	Range	Description	Default value
	WEIR_HEIGHT	m + datum	-10000 to 10000	The height of the weir. Water can flow past the weir when the water level exceeds the weir's height.	n/a
	WEIR_WIDTH	m	0 to 10000	The width of the weir.	5
	WEIR_ANGLE	geo angle (0-360°)	-1.7976931348623157E308 to 1.7976931348623157E308	The top down orientation angle of the weir.	0
	WEIR_COEFFICIENT	coefficient	0 to 10000	The flow coefficient related to the shape of the weir.	1,1
	WEIR_N	exponent	0 to 3.4028235E38	Weir shape exponent	1.5
	WEIR_TARGET_LEVEL	m + datum	-10000 to 10000	The Weir can be configured to adjust it's height automatically in order to reach the target upstream water level. This parameter is optional.	n/a

Notes

• If a weir is placed in a waterway, and the waterway is not otherwise interrupted, water might be able to flow past the weir via the waterway itself. In order to obstruct the waterway, one of two options can be chosen:
  • Define the weir angle, in which case the Tygron Platform will automatically raise the DEM in the simulation based on the position, width and angle of the weir.
  • Manually raise the terrain height using the terrain height tool or applying a terrain height GeoTIFF.
• Weirs can be imported as points. The Rasterization model and Water Module will always position a weir using its center-point, and orient its flow direction using the optional weir angle. The elevation is raised along the line perpendicular to the flow direction, up to the extended width of weir.

• 
  Weir placed along a waterway. Elevation is raised along the line perpendicular to the weir angle.
• 

How-to's

• How to correct multiple buildings on the same location
• How to correct weir, pump, or culvert drawn as point
• How to correct a building in an uninterrupted waterway
• How to correct a building at the edge of the project area

See also

• Weir formula (Water Overlay)
• Weir height test case (Water Module)
• Weir dam multiplier (Water Overlay)
• Weir dam surplus height m (Water Overlay)
• Weir dam output (Water Overlay)

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Water Module

Water Module

Tutorials

Overview

Theory

Benchmarks

Group

Hydraulic structures

Inlet

Inlet q • Inlet area • Inlet capacity •  Lower threshold •  Upper threshold • Inlet underground

Pump

Pump q •  Lower threshold •  Upper threshold • Pump angle • Pump capacity • Pump area

Culvert

Culvert diameter • Culvert rectangular height • Culvert threshold • Culvert n

Weir

Weir height • Weir width • Weir angle • Weir coefficient • Weir n • Weir target level

Sewer overflow

Sewer overflow • Sewer overflow speed

Drainage

Drainage q • Drainage datum • Drainage active • Drainage overflow threshold

Output

Object flow output • Object height output • Object datum output a • Object datum output b • Object water area output • Object width output • Weir dam output

Related

Building attributes • Hydrological features •  Terrain attributes • Model attributes • Results • Simulation data