Broad-Crested Weirs - Revision history

Mpollei@gfnet.com at 14:53, 25 July 2023

2023-07-25T14:53:18Z

← Older revision		Revision as of 14:53, 25 July 2023
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	[[Category:Spillway Control Structures]]		[[Category:Spillway Control Structures]]
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	“A weir is a notch of regular form through which water flows. The structure containing the notch is also called a weir. The edge over which the water flows is the crest. The two basic types of [[weirs]] are sharp-crested weirs and broad-crested weirs. Most hydraulic structures have broad-crested weirs. The crest is horizontal		{{Picture
	and long in the direction of flow so flow maintains contact with the crest rather than springing clear. The level crest in an earthen auxiliary spillway of a flood control dam is an example of a broad-crested weir."<ref name="NRCS650">[[National Engineering Handbook: Chapter 3 - Hydraulics\|National Engineering Handbook, Part 650, Chapter 3 - Hydraulics, NRCS, 2021]]</ref>		<!-- Add image file name (ex.image.jpg) -->
			\|image= Cromwell_Weir.jpg
			<!--Add link if applicable -->
			\|link=
			<!-- Add picture caption -->
			\|caption= Cromwell Weir, Nottinghamshire.
			(Image Source: [https://commons.wikimedia.org/wiki/File:Cromwell_Weir_-_Nottinghamshire_(Geograph_2561867_by_Jonathan_Thacker).jpg Jonathan Thacker])
			}}

			“A weir is a notch of regular form through which water flows. The structure containing the notch is also called a weir. The edge over which the water flows is the crest. The two basic types of [[weirs]] are [[Sharp-Crested Weirs\|sharp-crested weirs]] and broad-crested weirs. Most hydraulic structures have broad-crested weirs. The crest is horizontal and long in the direction of flow so flow maintains contact with the crest rather than springing clear. The level crest in an earthen auxiliary spillway of a flood control dam is an example of a broad-crested weir."<ref name="NRCS650">[[National Engineering Handbook: Chapter 3 - Hydraulics\|National Engineering Handbook, Part 650, Chapter 3 - Hydraulics, NRCS, 2021]]</ref>

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Grichards at 21:17, 13 December 2022

2022-12-13T21:17:29Z

← Older revision		Revision as of 21:17, 13 December 2022
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	[[Category:Spillway Control Structures]]		[[Category:Spillway Control Structures]]
	----		----
			“A weir is a notch of regular form through which water flows. The structure containing the notch is also called a weir. The edge over which the water flows is the crest. The two basic types of [[weirs]] are sharp-crested weirs and broad-crested weirs. Most hydraulic structures have broad-crested weirs. The crest is horizontal
	~~“An overflow~~ structure on which the ~~nappe~~ is ~~supported for an appreciable length~~ in the direction of flow. ”.<ref name="~~FEMA~~">[[ ~~Federal Guidelines for Dam Safety~~: ~~Glossary of Terms (FEMA P~~-~~148)~~ \| ~~Federal Guidelines for Dam Safety: Glossary of Terms (FEMA P~~-~~148)~~, ~~FEMA~~, ~~2004~~]]</ref>		and long in the direction of flow so flow maintains contact with the crest rather than springing clear. The level crest in an earthen auxiliary spillway of a flood control dam is an example of a broad-crested weir."<ref name="NRCS650">[[National Engineering Handbook: Chapter 3 - Hydraulics\|National Engineering Handbook, Part 650, Chapter 3 - Hydraulics, NRCS, 2021]]</ref>

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Grichards at 21:12, 13 December 2022

2022-12-13T21:12:10Z

← Older revision		Revision as of 21:12, 13 December 2022
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	~~“These types of control structures are associated with staged releases and suited for auxiliary and [[Emergency Spillways\|emergency spillways]]. A fuseplug control~~ structure ~~may include one or multiple bays containing~~ the fuseplug embankments. The zoned embankments will be placed to a specified height and include a pilot channel through each embankment crest set to a specified elevation associated with a given flood event. The pilot channel(s) and the number of fuseplug embankments are set to limit the discharge for given ranges of reservoir water surfaces. Fuseplug [[spillways]] should only operate during remote flood events, where more frequent flood events are accommodated by reservoir flood surcharge and discharge from service spillways and/or [[Outlet Works\|outlet works]]. An important consideration is the very large discharge capacity associated with [[operation]] from a small increase in reservoir water surface. The large amount of flow that could be released from an operating fuseplug must be carefully evaluated in terms of downstream impacts. Other considerations include evaluating and mitigating erosion potential both upstream (due to reservoir wave actions) and downstream of the fuseplug that could lead to headcutting and undermining the fuseplug control structure. Also, careful and thorough design and [[construction]] of the embankments are needed to ensure proper operation of the fuseplug spillway. Additionally, note that once a fuseplug spillway operates, the reservoir cannot be maintained above the control structure crest (base of the control structure containing the fuseplug embankments). This could result in the ~~loss~~ of ~~reservoir storage until the fuseplug embankment(s) has been reconstructed~~. ~~Finally, this type of spillway is applicable to concrete, embankment, and composite dams”~~.<ref name="~~DS14~~">[[~~Design Standards No. 14~~: ~~Appurtenant Structures for Dams~~ (~~Ch. 3: General Spillway Design Considerations~~) \| ~~Design Standards No. 14~~: ~~Appurtenant Structures for Dams~~ (~~Ch. 3: General Spillway Design Considerations~~), ~~USBR~~, ~~2014~~]]</ref>		“An overflow structure on which the nappe is supported for an appreciable length in the direction of flow. ”.<ref name="FEMA">[[ Federal Guidelines for Dam Safety: Glossary of Terms (FEMA P-148) \| Federal Guidelines for Dam Safety: Glossary of Terms (FEMA P-148), FEMA, 2004]]</ref>

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Grichards: Created page with "NOTOC Category:Spillway Control Structures ---- “These types of control structures are associated with staged releases and suited for auxiliary and emergency spillways. A fuseplug control structure may include one or multiple bays containing the fuseplug embankments. The zoned embankments will be placed to a specified height and include a pilot channel through each embankment crest set to a specified elevation associated with a given fl..."

2022-12-13T21:07:37Z

Created page with "__NOTOC__ Category:Spillway Control Structures ---- “These types of control structures are associated with staged releases and suited for auxiliary and emergency spillways. A fuseplug control structure may include one or multiple bays containing the fuseplug embankments. The zoned embankments will be placed to a specified height and include a pilot channel through each embankment crest set to a specified elevation associated with a given fl..."

New page

__NOTOC__
[[Category:Spillway Control Structures]]
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“These types of control structures are associated with staged releases and suited for auxiliary and [[Emergency Spillways|emergency spillways]]. A fuseplug control structure may include one or multiple bays containing the fuseplug embankments. The zoned embankments will be placed to a specified height and include a pilot channel through each embankment crest set to a specified elevation associated with a given flood event. The pilot channel(s) and the number of fuseplug embankments are set to limit the discharge for given ranges of reservoir water surfaces. Fuseplug [[spillways]] should only operate during remote flood events, where more frequent flood events are accommodated by reservoir flood surcharge and discharge from service spillways and/or [[Outlet Works|outlet works]]. An important consideration is the very large discharge capacity associated with [[operation]] from a small increase in reservoir water surface. The large amount of flow that could be released from an operating fuseplug must be carefully evaluated in terms of downstream impacts. Other considerations include evaluating and mitigating erosion potential both upstream (due to reservoir wave actions) and downstream of the fuseplug that could lead to headcutting and undermining the fuseplug control structure. Also, careful and thorough design and [[construction]] of the embankments are needed to ensure proper operation of the fuseplug spillway. Additionally, note that once a fuseplug spillway operates, the reservoir cannot be maintained above the control structure crest (base of the control structure containing the fuseplug embankments). This could result in the loss of reservoir storage until the fuseplug embankment(s) has been reconstructed. Finally, this type of spillway is applicable to concrete, embankment, and composite dams”.<ref name="DS14">[[Design Standards No. 14: Appurtenant Structures for Dams (Ch. 3: General Spillway Design Considerations) | Design Standards No. 14: Appurtenant Structures for Dams (Ch. 3: General Spillway Design Considerations), USBR, 2014]]</ref>


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