Floodgate

Last updated
Tokyo floodgates created to protect from typhoon surges Floodgate Tokyo.jpg
Tokyo floodgates created to protect from typhoon surges

Floodgates, also called stop gates, are adjustable gates used to control water flow in flood barriers, 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

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) and over the top of the structure. Historically, these gates used stacked timbers known as stoplogs or wooden panels known as flashboards to set the dam's crest height. Some floodgates known as coupures 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 sluice gate on the Harran canal Harran canal-GAP.jpg
A sluice gate on the Harran canal
A flood wall gate at Harlan, Kentucky Floodgate floodwall.jpg
A flood wall gate at Harlan, Kentucky
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
A US Army Corps of Engineers hinged bascule crest gate during installation Floodgate crest bascule.jpg
A US Army Corps of Engineers hinged bascule crest gate during installation
Fish belly flap gates at the Scrivener Dam, Canberra Scrivener Dam.jpg
Fish belly flap gates at the Scrivener Dam, Canberra
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.
Tainter gate diagram LgRadialGatefigc4-6.jpg
Tainter gate diagram
Tainter gates and spillway Tainter gates.jpg
Tainter gates and spillway
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.
Drum gates are controlled with valves. Drumgate.png
Drum gates are controlled with valves.
Drum gates on a diversion dam Floodgate drum.JPG
Drum gates on a diversion 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.
A roller gate on the Mississippi. Floodgate roller.jpg
A roller gate on the Mississippi.
Clamshell floodgates at the Arrowrock Dam. Floodgate clamshell.JPG
Clamshell floodgates at the Arrowrock Dam.
Fusegates are a mechanism designed to provide the controlled release of water in the event of exceptionally large floods. The design 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, but in excessive flood conditions they are designed to topple forward, allowing the controlled discharge of water. Multiple fusegates are generally set up side by side, with each fusegate designed to release under progressively extreme flooding, thus minimizing the impact of the floodwater on the river downstream. [1] The System was invented and patented by François Lempérière [2] for Hydroplus (Paris, France), subsidiary of GTM Entrepose. It has been installed on more than 50 dams around the world with sizes ranging from 1 m to more than 9 m 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 Typical fusegate.jpg
Typical fusegate sketch
Fusegate in Terminus Dam - Lake Kaweah Terminus Hydroplus.JPG
Fusegate in Terminus Dam - Lake Kaweah
Mitre gates

Valves

[ clarification needed ]

Discharge from a Howell-Bunger valve Howell-Bunger valve.jpg
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 ]

Physics

Opened floodgates at the Merikoski Power Plant in Oulu, Finland

The force on a rectangular flood gate can be calculated by the following equation:

where:

F = force measured in newtons (N)
p = pressure measured in pascal (Pa)
where:
A = area = rectangle: length × height measured in m2
where:
length = the horizontal length of a rectangular floodgate measured in metres
height = the height of a non-submerged flood gate from the bottom of the water column to the water surface measured in metres

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

Related Research Articles

<span class="mw-page-title-main">Water turbine</span> Type of turbine

A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work.

<span class="mw-page-title-main">Dam</span> Barrier that stops or restricts the flow of surface or underground streams

A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions.

<span class="mw-page-title-main">Thermal insulation</span> Minimization of heat transfer

Thermal insulation is the reduction of heat transfer between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials.

Flow measurement is the quantification of bulk fluid movement. Flow can be measured using devices called flowmeters in various ways. The common types of flowmeters with industrial applications are listed below:

<span class="mw-page-title-main">Weir</span> Artificial river barrier

A weir or low-head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of lakes, ponds, and reservoirs. There are many weir designs, but commonly water flows freely over the top of the weir crest before cascading down to a lower level. There is no single definition as to what constitutes a weir.

<span class="mw-page-title-main">Diversion dam</span>

A diversion dam is a dam that diverts all or a portion of the flow of a river from its natural course. Diversion dams do not generally impound water in a reservoir; instead, the water is diverted into an artificial water course or canal, which may be used for irrigation or return to the river after passing through hydroelectric generators, flow into a different river or be itself dammed forming an onground or groundwater reservoir or a storm drain.

<span class="mw-page-title-main">Siphon</span> Device involving the flow of liquids through tubes

A siphon is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered by the fall of the liquid as it flows down the tube under the pull of gravity, then discharging at a level lower than the surface of the reservoir from which it came.

<span class="mw-page-title-main">Tap (valve)</span> Valve controlling the release of a liquid or gas

A tap is a valve controlling the release of a fluid.

<span class="mw-page-title-main">Hydraulic engineering</span> Sub-discipline of civil engineering concerned with the flow and conveyance of fluids

Hydraulic engineering as a sub-discipline of civil engineering is concerned with the flow and conveyance of fluids, principally water and sewage. One feature of these systems is the extensive use of gravity as the motive force to cause the movement of the fluids. This area of civil engineering is intimately related to the design of bridges, dams, channels, canals, and levees, and to both sanitary and environmental engineering.

<span class="mw-page-title-main">Spillway</span> Structure for controlled release of flows from a dam or levee

A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure that water does not damage parts of the structure not designed to convey water.

<span class="mw-page-title-main">Penstock</span> Intake structure that controls water flow to turbines or sewerage systems

A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is of Scots origin, and was inherited from the earlier technology of mill ponds and watermills, with penstocks diverting pond waters to drive the mills.

<span class="mw-page-title-main">Hydraulic head</span> Specific measurement of liquid pressure above a vertical datum

Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum.

<span class="mw-page-title-main">Tainter gate</span> Type of radial arm floodgate

The Tainter gate is a type of radial arm floodgate used in dams and canal locks to control water flow. It is named for its inventor, Wisconsin structural engineer Jeremiah Burnham Tainter.

Streamflow, or channel runoff, is the flow of water in streams and other channels, and is a major element of the water cycle. It is one runoff component, the movement of water from the land to waterbodies, the other component being surface runoff. Water flowing in channels comes from surface runoff from adjacent hillslopes, from groundwater flow out of the ground, and from water discharged from pipes. The discharge of water flowing in a channel is measured using stream gauges or can be estimated by the Manning equation. The record of flow over time is called a hydrograph. Flooding occurs when the volume of water exceeds the capacity of the channel.

<span class="mw-page-title-main">Stoplogs</span> Elements of floodgates to adjust water level and discharge

Stoplogs are hydraulic engineering control elements that are used in floodgates to adjust the water level or discharge in a river, canal, or reservoir. Stoplogs are sometimes confused with flashboards, as both elements are used in bulkhead or crest gates. Stoplogs are typically long rectangular timber beams or boards that are placed on top of each other and dropped into premade slots inside a weir, gate, or channel. Present day, the process of adding and removing stoplogs is not manual, but done with hydraulic stoplog lifters and hoists. Since the height of the barrier can only be adjusted through the addition and removal of stoplogs, finding a lighter and stronger material other than wood or concrete became a more desirable choice. Other materials, including steel and composites, can be used as stoplogs as well. Stoplogs are designed to cut off or stop flow through a conduit.

<span class="mw-page-title-main">Akimoto Lake</span> Lake in Fukushima Prefecture, Japan

Akimoto Lake (秋元湖) is a lake in Fukushima Prefecture, Japan. Straddling the border of the village of Kitashiobara and the town of Inawashiro, it is used as a reservoir, providing drinking water to local residents. Along with Hibara Lake and Onogawa Lake, it forms what is known as the "Inner Bandai Plateau Tri-Lake Formation" of the Bandai Highland.

<span class="mw-page-title-main">Gulf Intracoastal Waterway West Closure Complex</span> Bridge in Plaquemines Parish, Louisiana

The Gulf Intracoastal Waterway West Closure Complex is a part of the New Orleans Drainage System; it consists of a navigable floodgate, a pumping station, flood walls, sluice gates, foreshore protection, and an earthen levee. The complex was designed to reduce risk for residences and businesses in the project area from a storm surge associated with a tropical event, with an intensity that has a one percent chance of occurring in any given year. This project was operated for the first time on August 29, 2012, in response to Hurricane Isaac.

Glenfield is a large industrial manufacturing company based in Kilmarnock, Ayrshire, Scotland. At its height it was reckoned to be the largest company of its type in the Commonwealth.

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. This differs for a dam or reservoir, for which a waste weir is another name for a spillway, i.e. not having the boards to adjust the water height nor the paddles to drain all the water as on a canal, only to drain the excess.

<span class="mw-page-title-main">River Foss Barrier</span> Floodgate in York, England

The Foss Barrier consists of a retractable floodgate and pumping station owned and managed by the Environment Agency. It straddles the River Foss in York, just above the confluence with the River Ouse. The barrier’s purpose is to prevent water from the Ouse flowing upstream into the Foss, raising water levels and flooding properties along the River Foss. The pumps next to the flood gate move water around the barrier via a side culvert so that it can continue to drain into the Ouse. This prevents water levels on the Foss rising when the barrier is closed. The Ouse’s normal water level at York is approximately 5 metres AOD. When the river level reaches 7.5 metres AOD, the barrier is lowered into the Foss, shutting it off from the Ouse. The electrically driven barrier takes less than five minutes to lower into position. The barrier operates as a ‘turn and lift’ gate so it opens and closes in a similar way to a garage door. The pump-house attached to the barrier maintain the water level in the Foss at around 6.5 metres AOD. When the flood subsides and the level of the Ouse drops back to 6.5 metres, the levels in both rivers are equalised so the barrier opens, and the pumps shut down.

References

  1. "Fusegate Operation". www.Hydroplus.com. Archived from the original on 2013-10-23. Retrieved 2013-11-21.
  2. "Patents by Inventor Francois Lemperiere". Justia Patents.

Sources