A flow control structure is a device that alters the flow of water in a

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...

, drainage channel or pipe. As a group these are passive structures since they operate without intervention under different amounts of water flow and their impact changes based on the quantity of water available. This includes

weir 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 l ...

s, flow splitters and proprietary-design devices that are used for

stormwater Stormwater, also spelled storm water, is water that originates from precipitation (storm), including heavy rain and meltwater from hail and snow. Stormwater can soak into the soil ( infiltrate) and become groundwater, be stored on depressed la ...

management and in

combined sewer A combined sewer is a type of gravity sewer with a system of pipes, tunnels, pump stations etc. to transport sewage and urban runoff together to a sewage treatment plant or disposal site. This means that during rain events, the sewage gets dilute ...

s.Metropolitan Council, St. Paul, MN (2001). ''Urban Small Sites Best Management Practice Manual.''
"Flow Control Structures: Flow Splitters."

"Permeable Weirs."

"Proprietary Flow Control Devices."
Flow-control structures are known to have existed for thousands of years. Some built by the

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...

have been in continuous use for over 2,000 years. The Chinese used these structures to divert water to

irrigate Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been develop ...

fields and to actually deposit

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

in specific areas so that the channels were not blocked by silt build-up. Structures like this required yearly maintenance to remove the accumulated silt. More modern structures add to these basic principles. In

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

, there are numerous flow-control structures that have been built to irrigate the

pineapple The pineapple (''Ananas comosus'') is a tropical plant with an edible fruit; it is the most economically significant plant in the family Bromeliaceae. The pineapple is indigenous to South America, where it has been cultivated for many centuri ...

and sugar cane fields. The purpose of these structures is to divert water into the various canals and to keep them full. When over full, they dump excess water back into either streams or other canals. Among the simplest is a low

dam 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, a ...

across a shallow stream, forcing all of the water to one side to allow it to be easily collected in a canal. This can keep a canal full even with very low flows in a stream. Another simple device is a series of

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

piers installed in a spillway to slow down the descending water so that it does not cause damage at the bottom of the spillway.

Applications

* Low-impact development * Sustainable drainage system *

Water-sensitive urban design Water-sensitive urban design (WSUD) is a land planning and engineering design approach which integrates the urban water cycle, including stormwater, groundwater, and wastewater management and water supply, into urban design to minimise environme ...

References

{{Stormwater structures Hydraulic engineering Infrastructure Stormwater management

Applications

See also

References