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floodgate

 
Dictionary: flood·gate   (flŭd'gāt') pronunciation
n.
  1. A gate used to control the flow of a body of water. Also called water gate.
  2. Something that restrains a flood or outpouring: The ruling opened the floodgates to refugees seeking asylum.

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WordNet: floodgate
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Note: click on a word meaning below to see its connections and related words.

The noun has one meaning:

Meaning #1: regulator consisting of a valve or gate that controls the rate of water flow through a sluice
  Synonyms: sluicegate, sluice valve, penstock, head gate, water gate


Wikipedia: Floodgate
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Tokyo floodgates created to protect from typhoon surges

Floodgates are adjustable gates used to control water flow in reservoir, river, stream, or levee systems. They may be designed to set spillway crest heights in dams, to adjust flow rates in sluices and canals, or they may be designed to stop water flow entirely as part of a levee or storm surge system. Since most of these devices operate by controlling the water surface elevation being stored or routed, they are also known as crest gates. In the case of flood bypass systems, floodgates sometimes are also used to lower the water levels in a main river or canal channels by allowing more water to flow into a flood bypass or detention basin when the main river or canal is approaching a flood stage.

Contents

Types

A sluice gate on the Harran canal
A flood wall gate at Harlan, Kentucky
  • Bulkhead gates are vertical walls with movable, or re-movable, sections. Movable sections can be lifted to allow water to pass underneath (as in a sluice gate). Designs with removable sections allow water to pass over top and historically used stacked timbers, which are known as stoplogs or flashboards, to set the dam's crest height. Some floodgates in large levee systems slide sideways to open for various traffic. Bulkhead gates can also be made of other materials and used as a single bulkhead unit. Miter gates are used in ship locks and usually close at an 18° angle to approximate an arch.


A hinged crest gate during installation
Fish belly flap gates at the Scrivener Dam, Canberra
  • Hinged crest gates, are wall sections that rotate from vertical to horizontal, thereby varying the height of the dam. They are generally controlled with hydraulic power, although some are passive and are powered by the water being impounded.
Variations;
  • flap gate
  • fish-belly flap gates
  • Bascule gates
  • Pelican gates


Tainter gate diagram
Tainter gates and spillway
  • Radial gates are rotary gates consisting of cylindrical sections. They may rotate vertically or horizontally. Tainter gates are a vertical design that rotates up to allow water to pass underneath. Low friction trunnion bearings, along with a face shape that balances hydrostatic forces, allow this design to close under its own weight as a safety feature.


Drum gates are controlled with valves.
Drum gates on a diversion dam
  • Drum gates are hollow gate sections that float on water. They are pinned to rotate up or down. Water is allowed into or out of the flotation chamber to adjust the dam's crest height.


A roller gate on the Mississippi.
Clamshell floodgates at the Arrowrock Dam.
  • Roller gates are large cylinders that move in an angled slot. They are hoisted with a chain and have a cogged design that interfaces with their slot.
  • Clamshell gates have an external clamshell leaf design.


  • Fusegates Fusegate System is an innovative spillway control technology, which consists of free standing blocks (the Fusegates) set side by side on a flattened spillway sill. The Fusegate blocks act as a fixed weir most of the time and operate independently without any remote control or energy source only in case of excessive flood conditions. The System is developed and patented by Hydroplus from Paris, France. It has been installed on more than 50 dams around the world with sizes ranging from 1m to more than 9m in height. Fusegate are typically used to increase the storage capacity of existing dams or to maximize the discharge potential of undersized spillways.


Typical fusegate sketch
Fusegate in Terminus Dam - Lake Kaweah


Valves

[clarification needed]

Discharge from a Howell-Bunger valve

Valves used in floodgate applications have a variety of design requirements and are usually located at the base of dams. Often, the most important requirement (besides regulating flow) is energy dissipation. Since water is very heavy, it exits the base of a dam with the enormous force of water pushing from above. Unless this energy is dissipated, the flow can erode nearby rock and soil and damage structures.

Other design requirements include taking into account pressure head operation, the flow rate, whether the valve operates above or below water, and the regulation of precision and cost.[citation needed]

  • Fixed cone valves, also known as Howell-Bunger valves, are designed to dissipate the energy from a water flow during reservoir discharge. They are a round pipe section with an adjustable sleeve gate and cone at the discharge end. Flow is varied by moving the sleeve away or towards its cone seat. The design allows high pressure water from the base of a dam to be released without causing erosion to the surrounding environment. Fixed cone valves are able to handle heads up to 300 m.
  • Hollow jet valves are a type of needle valve used for floodgate discharge. A cone and seat are inside a pipe. Water flows through an annular gap between the pipe and cone when it is moved downstream, away from the seat. Ribs support the bulb assembly and supply air for water jet stabilization.
  • Ring jet valves are similar to fixed cone valves, but have an integral collar that discharges water in a narrow stream. They are suitable for heads up to 50 m.
  • Jet flow gate, similar to a gate valve but with a conical restriction prior to the gate leaf that focuses the water into a jet. They were developed in the 1940s by the United States Bureau of Reclamation to allow fine control of discharge flow without the cavitation seen in regular gate valves. Jet flow gates are able to handle heads up to 150 m.


Physics

In order to do a simple calculation of the force on a rectangular flood gate one can use the following equation:

\ F = pA

where:

F = force measured in the SI units kg·m·s–2 which is called the newton (N)
p = pressure = \rho g h\, measured in N/m2, which is called the pascal (Pa)
where:
A = area = rectangle : length × height measured in m2
where:
length = the horizontal length of a rectangular floodgate measured in meters
height = the height of a non-submerged flood gate from the bottom of the water column to the water surface measured in meters

If the rectangular flood gate is submerged below the surface the same equation can be used but only the height from the water surface to the middle of the gate must be used to calculate the force on the flood gate.

See also

References

Sources

Notes

External links


Translations: Floodgate
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Dansk (Danish)
n. - sluse

idioms:

  • open the floodgates    åbne sluserne, åbne på vid gab

Nederlands (Dutch)
sluisdeur, iets wat een uitbarsting tegen gaat

Français (French)
n. - vanne, vannes

idioms:

  • open the floodgates    lever les vannes, être la porte ouverte à

Deutsch (German)
n. - Schleusentor

idioms:

  • open the floodgates    (fig) Tür und Tor öffnen

Ελληνική (Greek)
n. - θυρόφραγμα, θύρα υδροφράκτη/υδατοφράκτη

idioms:

  • open the floodgates    ανοίγω τους κρουνούς, μπήγω τα κλάματα

Italiano (Italian)
chiusa, chiuse

Português (Portuguese)
n. - eclusa (f)

idioms:

  • open the floodgates    abrir as comportas (fig.)

Русский (Russian)
шлюз

idioms:

  • open the floodgates    давать волю

Español (Spanish)
n. - compuerta, esclusa

idioms:

  • open the floodgates    remover las restricciones de algo, hacer algo que permita a alguien expresar sus sentimientos

Svenska (Swedish)
n. - dammlucka

中文(简体)(Chinese (Simplified))
水门, 防潮水闸, 水闸

idioms:

  • open the floodgates    打开水闸, 发泄出来

中文(繁體)(Chinese (Traditional))
n. - 水門, 防潮水閘, 水閘

idioms:

  • open the floodgates    打開水閘, 發洩出來

한국어 (Korean)
n. - 수문, 배출구

日本語 (Japanese)
n. - 水門, 防潮門, 堰, はけ口

العربيه (Arabic)
‏(الاسم) بوابه التحكم في تدفق الماء‏

עברית (Hebrew)
n. - ‮שער סכר, ריסון אחרון לדמעות, זעם וכו'‬


 
 

 

Copyrights:

Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
WordNet. WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Floodgate" Read more
Translations. Copyright © 2007, WizCom Technologies Ltd. All rights reserved.  Read more

 

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