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A wing dam or wing dike is a man made barrier that, unlike a conventional
A wing dam or wing dike is a man made barrier that, unlike a conventional 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 ...
, only extends partway into a river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
. These structures force water into a fast-moving center channel which reduces the rate of sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
accumulation, while slowing water flow near the riverbanks.
The Mississippi River
The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...
in North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
has thousands of wing dams which were originally constructed to reduce the amount of dredging
Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing da ...
required when the main navigation channel
Channel, channels, channeling, etc., may refer to:
Geography
* Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water.
Australia
* Channel Country, region of outback Austral ...
was maintained to at least . Since that time, additional conventional dams have been built to increase the water level in the river, doubling the depth of the navigation channel to . The wing dams still serve their purpose, but to a lesser extent than before.
While wing dams assist in assuring that rivers are navigable, they can also pose a threat to boaters. Many wing dams are often underwater and may be difficult to see, and can easily be struck by vessels. On the other hand, fishermen intentionally fish the quieter waters downstream of wing dams.
The action of wing dams is complex. Where they are installed, sediment is removed from the center of the river, but sediment is also carried further down the river where it has secondary effects. Some researchers believe that flooding is increased by wing dams; a 2013 theoretical analysis predicts that wing dams may lead to water level lowering for in-bank flows and to water level increases for out-of-bank (flood) flows.
See also
*Groyne
A groyne (in the U.S. groin) is a rigid hydraulic structure built perpendicularly from an ocean shore (in coastal engineering) or a river bank, interrupting water flow and limiting the movement of sediment. It is usually made out of wood, concre ...
*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 ...
References
{{reflist Dams by type Water transport infrastructure Nautical terminology