A weir / w ɪər / 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.
26-605: Tuckasegee may refer to: Tuckasegee River , tributary of the Little Tennessee River in western North Carolina Tuckasegee, North Carolina , unincorporated community in Jackson County See also [ edit ] Tuckasegee darter , a species of darter fish Tuskegee (disambiguation) Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
52-488: A negative effect on fish species that migrate as part of their breeding cycle (e.g., salmonids ), but it also can be useful as a method of preventing invasive species moving upstream. For example, weirs in the Great Lakes region have helped to prevent invasive sea lamprey from colonising farther upstream. Mill ponds are created by a weir that impounds water that then flows over the structure. The energy created by
78-415: A range of biota , including poor swimmers. Even though the water around weirs can often appear relatively calm, they can be extremely dangerous places to boat, swim, or wade, as the circulation patterns on the downstream side—typically called a hydraulic jump —can submerge a person indefinitely. This phenomenon is so well known to canoeists, kayakers, and others who spend time on rivers that they even have
104-416: A rueful name for weirs: "drowning machines". The Ohio DNR recommends that a victim should "tuck the chin down, draw the knees up to the chest with arms wrapped around them. Hopefully, conditions will be such that the current will push the victim along the bed of the river until swept beyond the boil line and released by the hydraulic." The Pennsylvania State Police also recommends to victims, "curl up, dive to
130-646: A tributary into the Little Tennessee River below the lake. The name Tuckasegee may be an anglicization or transliteration of the Cherokee word daksiyi —[takhšiyi] in the local Cherokee variety, meaning 'Turtle Place.' Several Cherokee towns developed along the river, including Kituwa , believed to be the "mother town" of the Cherokee. It developed around an earthen platform mound , likely built about 1000 CE. The mound, although reduced in height,
156-449: A weir is broad-crested for much of its length, but has a section where the weir stops or is 'open' so that small boats and fish can traverse the structure. A notch weir is any weir where the physical barrier is significantly higher than the water level except for a specific notch (often V-shaped) cut into the panel. At times of normal flow all the water must pass through the notch, simplifying flow volume calculations, and at times of flood
182-422: A weir. Weirs can vary in size both horizontally and vertically, with the smallest being only a few centimetres in height whilst the largest may be many metres tall and hundreds of metres long. Some common weir purposes are outlined below. Weirs allow hydrologists and engineers a simple method of measuring the volumetric flow rate in small to medium-sized streams/rivers or in industrial discharge locations. Since
208-546: Is a stub . You can help Misplaced Pages by expanding it . This article about a location in Swain County, North Carolina is a stub . You can help Misplaced Pages by expanding it . This article related to a river in North Carolina is a stub . You can help Misplaced Pages by expanding it . Weirs Weir can also refer to the skimmer found in most in-ground swimming pools, which controls the flow of water pulled into
234-433: Is a clear distinction made between the structures. Usually, a dam is designed specifically to impound water behind a wall, whilst a weir is designed to alter the river flow characteristics. A common distinction between dams and weirs is that water flows over the top (crest) of a weir or underneath it for at least some of its length. Accordingly, the crest of an overflow spillway on a large dam may therefore be referred to as
260-405: Is a flat-crested structure, where the water passes over a crest that covers much or all of the channel width. This is one of the most common types of weir found worldwide. A compound weir is any weir that comprises several different designs into one structure. They are commonly seen in locations where a river has multiple users who may need to bypass the structure. A common design would be one where
286-473: Is a generic relationship and specific calculations are available for the many different types of weir. Flow measurement weirs must be well maintained if they are to remain accurate. The flow over a V-notch weir (in ft /s) is given by the Kindsvater–Shen equation: where As weirs are a physical barrier, they can impede the longitudinal movement of fish and other animals up and down a river. This can have
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#1732776032872312-538: Is believed that the weirs were built by peoples who lived here prior to the Cherokee in the Southeast. The weirs are most easily viewed when water levels are low. One near Webster, North Carolina , is the most intact and has a characteristic "V" shape. Fishing, hiking, and paddling are among the recreational opportunities along the river. This article about a location in Jackson County , North Carolina
338-454: Is visible on the 309 acres (1.25 km ) of land reacquired in 1996 by the federally recognized Eastern Band of Cherokee Indians . This land also includes the former site of an early 18th-century Cherokee town. The EBCI conducted an archeological survey in 1997 that found evidence of thousands of years of habitation at this site and are keeping it undeveloped as sacred ground. Many of the mounds in this area were built by about 1000 CE, during
364-576: The South Appalachian Mississippian culture era. In each of their major towns, the Cherokee built a townhouse as their expression of public architecture on top of such a mound, if it existed. The townhouse was the Cherokee expression of public architecture, emphasizing their decentralized society based on community consensus. In some places, they built a townhouse on the main town plaza. The river also has several stone fishing weirs built by prehistoric indigenous peoples. It
390-689: The confluence of Panthertown and Greenland creeks. It flows in a northwesterly direction into Swain County , where the Oconaluftee flows into it before the Tuckaseegee heads northwest. The county seat, Bryson City developed along both sides of the Tuckaseegee, and Bryson City Island Park was developed. The river next enters Fontana Lake , formed by the Fontana Dam upriver on the Little Tennessee River. The Tuckaseegee ultimately flows as
416-502: The bottom, and swim or crawl downstream". As the hydraulic jump entrains air, the buoyancy of the water between the dam and boil line will be reduced by upward of 30%, and if a victim is unable to float, escape at the base of the dam may be the only option for survival. There are many different types of weirs and they can vary from a simple stone structure that is barely noticeable, to elaborate and very large structures that require extensive management and maintenance. A broad-crested weir
442-501: The change in height of the water can then be used to power waterwheels and power sawmills, grinding wheels, and other equipment. Weirs are commonly used to control the flow rates of rivers during periods of high discharge. Sluice gates (or in some cases the height of the weir crest) can be altered to increase or decrease the volume of water flowing downstream. Weirs for this purpose are commonly found upstream of towns and villages and can either be automated or manually operated. By slowing
468-414: The design of a weir that ensure that fish can bypass the barriers and access upstream habitats. Unlike dams, weirs do not usually prevent downstream fish migration (as water flows over the top and allows fish to bypass the structure in that water), although they can create flow conditions that injure juvenile fish. Recent studies suggest that navigation locks have also potential to provide increased access for
494-443: The filtering system. The word likely originated from Middle English were , Old English wer , a derivative of the root of the verb werian, meaning "to defend, dam". The German cognate is Wehr , which means the same as English weir. Commonly, weirs are used to prevent flooding , measure water discharge, and help render rivers more navigable by boat. In some locations, the terms dam and weir are synonymous, but normally there
520-602: The geometry of the top of the weir is known and all water flows over the weir, the depth of water behind the weir can be converted to a rate of flow. However, this can only be achieved in locations where all water flows over the top of the weir crest (as opposed to around the sides or through conduits or sluices) and at locations where the water that flows over the crest is carried away from the structure. If these conditions are not met, it can make flow measurement complicated, inaccurate, or even impossible. The discharge calculation can be summarised as where However, this calculation
546-423: The maximum height a species can jump or creates flow conditions that cannot be bypassed (e.g., due to excessive water velocity) effectively limits the maximum point upstream that fish can migrate. In some cases this can mean that huge lengths of breeding habitat are lost, and over time this can have a significant impact on fish populations. In many countries, it is now a legal requirement to build fish ladders into
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#1732776032872572-413: The rate at which water moves downstream even slightly, a disproportionate effect can be had on the likelihood of flooding. On larger rivers, a weir can also alter the flow characteristics of the waterway to the point that vessels are able to navigate areas previously inaccessible due to extreme currents or eddies . Many larger weirs will have construction features that allow boats and river users to "shoot
598-427: The river bottom) that reduces the water oxygen content and smothers invertebrate habitat and fish spawning sites. The oxygen content typically returns to normal once water has passed over the weir crest (although it can be hyper-oxygenated), although increased river velocity can scour the river bed causing erosion and habitat loss. Weirs can have a significant effect on fish migration . Any weir that exceeds either
624-690: The title Tuckasegee . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Tuckasegee&oldid=809063311 " Categories : Disambiguation pages Place name disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Tuckasegee River The Tuckasegee River (variant spellings include Tuckaseegee and Tuckaseigee ) flows entirely within western North Carolina . It begins its course in Jackson County below Cullowhee at
650-515: The water level can rise and submerge the weir without any alterations made to the structure. A polynomial weir is a weir that has a geometry defined by a polynomial equation of any order n . In practice, most weirs are low-order polynomial weirs. The standard rectangular weir is, for example, a polynomial weir of order zero. The triangular (V-notch) and trapezoidal weirs are of order one. High-order polynomial weirs are providing wider range of Head-Discharge relationships, and hence better control of
676-546: The weir" and navigate by passing up or down stream without having to exit the river. Weirs constructed for this purpose are especially common on the River Thames , and most are situated near each of the river's 45 locks . Because a weir impounds water behind it and alters the flow regime of the river, it can have an effect on the local ecology . Typically, the reduced river velocity upstream can lead to increased siltation (deposition of fine particles of silt and clay on
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