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Weirs
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 water 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. ''Weir'' can also refer to the skimmer found in most in-ground swimming pools, which controls the flow of water pulled into the filtering system. Etymology 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. Function Commonly, weirs are used to prevent flooding, measure water discharge, and help render rivers more navigable by boat. In some location ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locks And Weirs On The River Thames
The England, English River Thames is navigable from Cricklade (for very small, shallow boats) or Lechlade (for larger boats) to the sea, and this part of the river falls 71 meters (234 feet). There are 45 lock (water navigation), locks on the river, each with one or more adjacent weirs. These lock and weir combinations are used for controlling the flow of water down the river, most notably when there is a risk of flooding, and provide for navigation above the tideway. History From ancient times there were many obstructions across the Thames, for fish-pounds and millers' weirs. They are referred to by Asserius Menevensis in the ninth century and Magna Carta (1215) states that "weirs, for the time to come, shall be demolished in the Thames and Medway, except on the sea coast." It appears this never happened. In the Middle Ages, the fall on the river in its middle and upper sections was used to drive watermills for the production of flour and paper and various other purposes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Culverts Under Yass River Walkway Weir
A culvert is a structure that channels water past an obstacle or to a subterranean waterway. Typically embedded so as to be surrounded by soil, a culvert may be made from a pipe, reinforced concrete or other material. In the United Kingdom, the word can also be used for a longer artificially buried watercourse. Culverts are commonly used both as cross-drains to relieve drainage of ditches at the roadside, and to pass water under a road at natural drainage and stream crossings. When they are found beneath roads, they are frequently empty. A culvert may also be a bridge-like structure designed to allow vehicle or pedestrian traffic to cross over the waterway while allowing adequate passage for the water. Dry culverts are used to channel a fire hose beneath a noise barrier for the ease of firefighting along a highway without the need or danger of placing hydrants along the roadway itself. Culverts come in many sizes and shapes including round, elliptical, flat-bottomed, open- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spillway
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. Spillways can include floodgates and fuse plugs to regulate water flow and reservoir level. Such features enable a spillway to regulate downstream flow—by releasing water in a controlled manner before the reservoir is full, operators can prevent an unacceptably large release later. Other uses of the term "spillway" include bypasses of dams and outlets of channels used during high water, and outlet channels carved through natural dams such as moraines. Water normally flows over a spillway only during flood periods, when the reservoir has reached its capacity and water continues entering faster than it can be released. In contrast, an intake tower is a structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humber Weir
The Humber is a large tidal estuary on the east coast of Northern England. It is formed at Trent Falls, Faxfleet, by the confluence of the tidal rivers River Ouse, Yorkshire, Ouse and River Trent, Trent. From there to the North Sea, it forms part of the boundary between the East Riding of Yorkshire on the north bank and North Lincolnshire on the south bank. Also known as the River Humber, it is tidal its entire length. Below Trent Falls, the Humber passes the junction with the Market Weighton Canal on the north shore, the confluence of the River Ancholme on the south shore; between North Ferriby and South Ferriby and under the Humber Bridge; between Barton-upon-Humber on the south bank and Kingston upon Hull on the north bank (where the River Hull joins), then meets the North Sea between Cleethorpes on the Lincolnshire side and the long and thin headland of Spurn, Spurn Head to the north. Ports on the Humber include the Port of Hull, the Port of Grimsby and the Port of Immin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siltation
Siltation is water pollution caused by particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments and to the increased accumulation (temporary or permanent) of fine sediments on bottoms where they are undesirable. Siltation is most often caused by soil erosion or sediment spill. It is sometimes referred to by the ambiguous term "sediment pollution", which can also refer to a chemical contamination of sediments accumulated on the bottom, or to pollutants bound to sediment particles. Although "siltation" is not perfectly stringent, since it also includes particle sizes other than silt, it is preferred for its lack of ambiguity. Causes The origin of the increased sediment transport into an area may be erosion on land or activities in the water. In rural areas, the erosion source is typically soil degradation by intensive or inadequate agricultural practices, leading to soil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecology
Ecology () is the natural science of the relationships among living organisms and their Natural environment, environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosystem, and biosphere levels. Ecology overlaps with the closely related sciences of biogeography, evolutionary biology, genetics, ethology, and natural history. Ecology is a branch of biology, and is the study of abundance (ecology), abundance, biomass (ecology), biomass, and distribution of organisms in the context of the environment. It encompasses life processes, interactions, and adaptations; movement of materials and energy through living communities; ecological succession, successional development of ecosystems; cooperation, competition, and predation within and between species; and patterns of biodiversity and its effect on ecosystem processes. Ecology has practical applications in fields such as conservation biology, wetland management, natural resource m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
River Thames
The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, second-longest in the United Kingdom, after the River Severn. The river rises at Thames Head in Gloucestershire and flows into the North Sea near Tilbury, Essex and Gravesend, Kent, via the Thames Estuary. From the west, it flows through Oxford (where it is sometimes called the Isis), Reading, Berkshire, Reading, Henley-on-Thames and Windsor, Berkshire, Windsor. The Thames also drains the whole of Greater London. The lower Reach (geography), reaches of the river are called the Tideway, derived from its long Tidal river, tidal reach up to Teddington Lock. Its tidal section includes most of its London stretch and has a rise and fall of . From Oxford to the estuary, the Thames drops by . Running through some of the drier parts of mainland Bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eddies
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle. This phenomenon is naturally observed behind large emergent rocks in swift-flowing rivers. An eddy is a movement of fluid that deviates from the general flow of the fluid. An example for an eddy is a vortex which produces such deviation. However, there are other types of eddies that are not simple vortices. For example, a Rossby wave is an eddy which is an undulation that is a deviation from mean flow, but does not have the local closed streamlines of a vortex. Swirl and eddies in engineering The propensity of a fluid to swirl is us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Current (fluid)
A current in a fluid is the magnitude and direction of flow within each portion of that fluid, such as a liquid or a gas. Types of fluid currents include: * Air current * Water current ** Current (hydrology), a current in a river or stream ** Ocean current An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, sh ... *** Longshore current *** Boundary current *** Rip current *** Rip tide *** Subsurface currents **** Turbidity current *** Tidal current See also * Laminar flow {{Fluiddynamics-stub Fluid dynamics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sluice Gates
A sluice ( ) is a water channel containing a sluice gate, a type of lock to manage the water flow and water level. There are various types of sluice gates, including flap sluice gates and fan gates. Different depths are calculated when design sluice gates. Sluices are used for channeling water toward a water mill, including for transporting logs from steep hillsides. Different terms are used regionally for sluices; the terms ''sluice'', ''sluice gate'', ''knife gate'', and ''slide gate'' are used interchangeably in the water and wastewater control industry. Etymology The term "sluice" originates from the Middle English word scluse, which derived from the Old French escluse (modern French: écluse). This, in turn, came from the Late Latin exclusa, a shortening of aqua exclusa, meaning "excluded water" or "a shut-off water channel." The Latin exclusa is the feminine past participle of excludere ("to shut out, exclude"), from *ex-* ("out") and claudere ("to close"). Regional ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
