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Elver Pass
An elver pass pass or eel pass is a waterway modification constructed to mitigate the effects of obstructions, especially manmade weirs, on waterways, watercourses, ditcheses, drains, channels and flumes, on the movement of eels, fish and elver (fish), elvers (juvenile eels). Powerful swimmers, including salmon and sea trout, find it easy to pass through many structures. However, it is widely accepted that some structures make fish migration more difficult upstream. Construction The UK Environment Agency has guidelines for the design of eel and elver passes for employment in weirs, tidal flaps & gates and sluice structures. A variety of materials for example High-density polyethylene, HDPE and stainless steel are used to construct brush and bristle surfaces, pipes, ducts, mouse holes, cat flaps and pet door types of eel and elver passes. Eel and elver passes are distinctive from Fish ladder, fish ladders which in turn are distinct from Eel ladder, eel ladders. The eel ladder i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 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 Navigability, navigable by boat. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stainless Steel
Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromium content of 11% or more, which forms a Passivation (chemistry), passive film that protects the material and can self-healing material, self-heal when exposed to oxygen. It can be further alloyed with elements like molybdenum, carbon, nickel and nitrogen to enhance specific properties for various applications. The alloy's properties, such as luster and resistance to corrosion, are useful in many applications. Stainless steel can be rolled into Sheet metal, sheets, plates, bars, wire, and tubing. These can be used in cookware, cutlery, surgical instruments, major appliances, vehicles, construction material in large buildings, industrial equipment (e.g., in paper mills, chemical plants, water treatment), and storage tanks and tankers for ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eels
Eels are ray-finned fish belonging to the order (biology), order Anguilliformes (), which consists of eight suborders, 20 Family (biology), families, 164 genus, genera, and about 1000 species. Eels undergo considerable development from the early larval stage to the eventual adult stage and are usually predators. The term "eel" is also used for some other eel-shaped fish, such as electric eels (genus ''Electrophorus''), swamp eels (order Synbranchiformes), and deep-sea spiny eels (family Notacanthidae). However, these other clades, with the exception of deep-sea spiny eels, whose order Notacanthiformes is the sister clade to true eels, convergent evolution, evolved their eel-like shapes independently from the true eels. As a main rule, most eels are marine. Exceptions are the catadromous genus Anguillidae, ''Anguilla'' and the Gymnothorax polyuranodon, freshwater moray, which spend most of their life in freshwater, the Fish migration#Classification, anadromous rice-paddy eel, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Eel
The European eel (''Anguilla anguilla'') is a species of eel. Their life history was a mystery for thousands of years, and mating in the wild has not yet been observed. The five stages of their development were originally thought to be different species. They are critically endangered due to hydroelectric dams, overfishing by fisheries on coasts for human consumption, and parasites. Description European eels undergo five stages of development in their lifecycle: larva (leptocephalus), glass eel, elver, yellow eel, and silver eel. Adults in the yellow phase are typically around and rarely reach more than , but they can reach a length of up to in exceptional cases. They have 110 to 120 vertebrae. tend to live approximately 15–20 years in the wild, although captive specimens have lived for over 80 years. One such specimen known as "the Brantevik Eel" lived for 155 years in the well of a family home in Brantevik, a fishing village in southern Sweden. Ecology Eels tend to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Council Of The European Union
The Council of the European Union, often referred to in the treaties and other official documents simply as the Council, and less formally known as the Council of Ministers, is the third of the seven institutions of the European Union (EU) as listed in the Treaty on European Union. It is one of two legislative bodies and together with the European Parliament serves to amend and approve, or veto, the proposals of the European Commission, which holds the right of initiative. The Council of the European Union and the European Council are the only EU institutions that are explicitly intergovernmental, that is, forums whose attendees express and represent the position of their Member State's executive, be they ambassadors, ministers or heads of state/government. The Council meets in 10 different configurations of national ministers (one per state). The precise membership of these configurations varies according to the topic under consideration; for example, when discussin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Level Commissioners
The Middle Level Commissioners are a land drainage authority in eastern England. The body was formed in 1862, undertaking the main water level management function within the Middle Level following the breakup of the former Bedford Level Corporation. The Middle Level is the central and largest section of the Great Level of The Fens, which was reclaimed by drainage during the mid-17th Century. The area is bounded on the northwest and east by the River Nene and Ouse washes, on the north by previously drained Marshland silts and to the south and west by low clay hills. The Middle Level river system consists of over of watercourses most of which are statutory navigations and has a catchment of over . History In the distant past Great Britain was part of continental Europe with the rivers of eastern England being tributaries of the River Rhine, which flowed across a flat, marshy plain, which is now the southern North Sea. Around 12,000 years ago, following the end of the last Ice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Fens
The Fens or Fenlands in eastern England are a naturally marshy region supporting a rich ecology and numerous species. Most of the fens were drained centuries ago, resulting in a flat, dry, low-lying agricultural region supported by a system of drainage channels and man-made rivers (Ditch, dykes and drains) and automated pumping stations. There have been unintended consequences to this reclamation, as the land level has continued to sink and the dykes have been built higher to protect it from flooding. ''Fen'' is the local term for an individual area of marshland or former marshland. It also designates the type of marsh typical of the area, which has pH, neutral or alkaline water and relatively large quantities of dissolved minerals, but few other plant nutrition, plant nutrients. The Fens are a National Character Area, based on their landscape, biodiversity, geodiversity and economic activity. The Fens lie inland of the Wash, and are an area of nearly in the south east of L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elver Pass During Manufacture Exposing Bristles
{{disambiguation, given name, surname ...
Elver may refer to: * Elver (fish), a juvenile eel * Elver pass, a river construction that allows fish & eels to migrate freely * Elver Eating World Championships People * Elmore Elver * Hilal Elver * Helena Elver * Élver James Melchor Bañol Élver James Melchor Bañol (born 1976) is a Colombian rapist and serial killer. He was convicted of 7 rapes and 4 murders, one of them being that of Rosmery Castellón, a minor. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eel Ladder
A fish ladder, also known as a fishway, fish pass, fish steps, or fish cannon, is a structure on or around artificial and natural barriers (such as dams, Lock (water transport), locks and waterfalls) to facilitate Fish migration#Classification, diadromous fishes' natural Fish migration, migration as well as movements of Fish migration#Classification, potamodromous species. Most fishways enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps (hence the term ''ladder'') into the waters on the other side. The velocity of water falling over the steps has to be great enough to attract the fish to the ladder, but it cannot be so great that it washes fish back downstream or exhausts them to the point of inability to continue their journey upriver. History Written reports of rough fishways date to 17th-century France, where bundles of branches were used to make steps in steep channels to bypass obstructions. A 1714 construction of an old ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Ladder
A fish ladder, also known as a fishway, fish pass, fish steps, or fish cannon, is a structure on or around artificial and natural barriers (such as dams, locks and waterfalls) to facilitate diadromous fishes' natural migration as well as movements of potamodromous species. Most fishways enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps (hence the term ''ladder'') into the waters on the other side. The velocity of water falling over the steps has to be great enough to attract the fish to the ladder, but it cannot be so great that it washes fish back downstream or exhausts them to the point of inability to continue their journey upriver. History Written reports of rough fishways date to 17th-century France, where bundles of branches were used to make steps in steep channels to bypass obstructions. A 1714 construction of an old channel bypassing a dam, "originally cut for the passage of fish up and down the river", is mentio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-density Polyethylene
High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or " polythene" when used for HDPE pipes. With a high strength-to-density ratio, HDPE is used in the production of plastic bottles, corrosion-resistant piping, geomembranes and plastic lumber. HDPE is commonly recycled, and has the number "2" as its resin identification code. In 2008, the global HDPE market reached a volume of more than 30 million tons. Properties HDPE is known for its high strength-to-density ratio. The density of HDPE ranges from 930 to 970 kg/m3. Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength (38 MPa versus 21 MPa) than LDPE. The difference in strength exceeds the difference in density, giving HDPE a higher specific strength. It is also harder and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waterway
A waterway is any Navigability, navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other ways. A first distinction is necessary between maritime shipping routes and waterways used by inland water craft. Maritime shipping routes cross oceans and seas, and some lakes, where navigability is assumed, and no engineering is required, except to provide the draft for deep-sea shipping to approach seaports (Channel (geography), channels), or to provide a short cut across an isthmus; this is the function of ship canals. Dredged channels in the sea are not usually described as waterways. There is an exception to this initial distinction, essentially for legal purposes, see under international waters. Where seaports are located inland, they are approached through a waterway that could be termed "inland" but in practice is generally referred to as a "maritime waterway ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
