Reservoir 3292675 225531075 2008-07-14T04:34:37Z Peter gk 1474065 corrected link to [[pl:Zbiornik retencyjny]] {{Unreferenced|date=December 2006}} {{Otheruses3|Reservoir (disambiguation)}} [[Image:Taiwan JungHua Dam.JPG|thumb|right|300px|The Jhonghua Dam on the Dahan River in [[Taoyuan County (Taiwan)|Taoyuan County]], [[Taiwan]]]] A '''reservoir''' is, most broadly, a place or hollow vessel where something (usually [[liquid]]) is kept in [[reserve]], for later use. Most often, a reservoir refers to an [[artificial]] [[lake]], used to store [[water]] for various uses. Reservoirs are created first by building a sturdy [[dam]], usually out of [[cement]], [[soil|earth]], [[rock (geology)|rock]], or a mixture. Once the dam is completed, a [[stream]] is allowed to flow behind it and eventually fill it to capacity. ==Construction== There are two basic types of reservoir: the commonly-seen dam across a [[valley]], or the less-common fully-bunded dam. A fully [[water tower]] bunded dam has a continuous human made [[embankment]] around its entire perimeter, most commonly using a central clay core as the waterproof element. The core is held in place by earth or rock piled either side of it in suitable volumes to resist the outward forces exerted by the water. The clay is joined directly to the natural underlying material, which itself is usually clay in order for the dam to be water tight. The reservoir is filled by mechanical pumps that draw water from an adjacent water course such as a river. If a water tight roof is added then this dam can then be used for storing treated water before it goes to the tap and is known as a "Service" reservoir. The more common dam across a valley relies on naturally formed features to form the water tight elements. Generally, [[surveying|surveyors]] have to find river valleys which are deep and narrow; the [[valley]] sides can then act as natural walls. The best place along the valley for building a dam has to be determined according to where the dam can best be tied into the valley walls and floor to form a water tight seal. If necessary, humans have to be re-housed and/or historic sites have to be moved, e.g. the temples of [[Abu Simbel]] before the construction of the [[Aswan Dam]], creating [[Lake Nasser]] in the [[Nile|Nile River]], [[Egypt]]. [[Image:yarrowreservoir.jpg|thumb|right|300px|A view across [[Yarrow Reservoir]], the newest of those built at [[Rivington]] in [[Lancashire]]]] First, the river must be redirected slightly so as to not disturb construction of the dam. Once that is done, building of the dam may commence. This may take anywhere from a few months to a few years, depending on its size and complexity. After the dam is complete, the river is allowed to begin filling the large area behind the dam. Some reservoirs are entirely underground. In the United Kingdom [[Thames Water]] has many underground reservoirs beneath [[London]] built in the 1800s by the Victorians, most of which are lined with thick layers of brick. Honor Oak Service reservoir, which was completed in 1909, is the largest of this type in Europe. The roof is supported using large brick pillars and arches and the outside surface is used as a [[golf]] course. ==Operation== A raw water reservoir doesn't simply hold water until it is needed. It is the first part of the [[water treatment]] process. The time the water is held for before it is released is known as the retention time, and is a design feature that allows larger particles and [[silt]]s to settle out as well as time for the biological treatment of algae and bacteria by plankton-like creatures that naturally live within the water. Water is then released from the reservoir, generally by [[gravity]], to be cleaned for [[drinking water]]. In the event that major [[rain]] occurs, water can be released, decreasing the reservoir's water level. ===Levels=== The normal maximum level of a reservoir lake is called '''full pool''', while the minimum level it can function at is '''dead pool'''. The water below this point is also called the dead pool, while the water in between is called the '''conservation pool'''. Full pool may have different levels in summer and winter, or based on the local wet and dry seasons. Once a reservoir reaches dead pool, it is below the level at which the dam can release it downstream. At this point, the streambed beyond the dam goes nearly or completely dry, and electricity production stops as well. This is also often the point at which intakes for [[municipal]] [[water system]]s begin to suck air in, and must be extended into deeper water, where [[stagnant]] [[water quality]] is much poorer. This can be done either permanently with longer pipes, or temporarily with large [[Hose (tubing)|hose]]s floated on small [[barge]]s, such as until a severe [[drought]] or dam [[repair]]s are over. ===Hydroelectricity=== A [[hydroelectricity|hydroelectric]] power station consists of large [[water turbine|turbines]] at the base of a dam. Water from the reservoir behind the dam is channeled through pipes and delivered to the turbines, which in turn, spin a [[generator]] to produce [[electricity]]. Generally, reservoirs behind hydroelectric dams are built specifically for electrical power generation and are not used for drinking water or irrigation. ===Controlling watercourses=== Reservoirs can be used in a number of ways to control how water flows through downstream waterways. ====Irrigation==== Water in an [[irrigation]] reservoir is released into networks of [[canal]]s mainly for use in [[farm]]lands or secondary water systems. Water in an irrigation reservoir is ''generally'' not used for drinking water, but in some cases is. As with all reservoirs, water can be released if the reservoir is too full. ====Flood control==== Commonly known as an "attenuation" or "balancing" reservoir, these are used to prevent [[flood]]ing to lower lying lands, [[flood]] control reservoirs collect water at times of unseasonally high rainfall, then release it slowly over the course of the following weeks or months. See [[transvasement]]. ====Compensation==== If a standard reservoir is built on a river which is used as a source of power, a compensation reservoir may also be built to guarantee a sufficient flow of water downstream during the working hours of the water-powered industries. ====Canals==== [[Image:KupferbachStauseeAachen.jpg|thumb|right|300px|Recreational-only Kupferbach reservoir near [[Aachen]]]] Where a natural watercourse's water is not available to be diverted into a [[canal]], a reservoir may be built to guarantee the water level in the canal; for example, where a canal climbs to cross a range of hills through [[Lock (water transport)|lock]]s. ===Recreation=== Reservoirs often provide for [[recreation]]al uses. Most reservoirs are built for a civic purpose, but still allow [[fishing]], [[boating]], and other activities. At most reservoirs, special rules apply for the safety of the public. ==History== Dry climate and water scarcity in [[India]] led to early development of water management techniques, including the building of a reservoir at [[Girnar]] in 3000 BCE.<ref name=Rodda/> Artificial lakes dating to the 5th century BCE have been found in ancient [[Greece]].<ref>Wilson & Wilson, page 8</ref> An artificial lake in present-day [[Madhya Pradesh]] province of India, constructed in the 11th century, covered 650 square meters. <ref name=Rodda>Rodda et al. (2004), page 161</ref> ==List of reservoirs== {{main|List of reservoirs}} ====Largest reservoir by region==== * [[Northern Europe]]: '''Lokka''' in the municipality of [[Sodankylä]] in Northern [[Finland]] 417&nbsp;km² * [[Western Europe]]: The [[IJsselmeer]] 1,250&nbsp;km² ===List of reservoirs by area=== {{Cleanup-section|date=May 2008}}<!-- most of these are not reservoirs --> {{Unreferencedsection|date=May 2008}} {{main|List of reservoirs by area}} The following are the world's ten largest reservoirs by surface area: #[[Lake Volta]] (8,482&nbsp;km²; [[Ghana]]) #[[Smallwood Reservoir]] (6,527&nbsp;km²; [[Canada]]) #[[Kuybyshev Reservoir]] (6,450&nbsp;km²; [[Russia]]) #[[Lake Kariba]] (5,580&nbsp;km²; [[Zimbabwe]], [[Zambia]]) #[[Bukhtarma Reservoir]] (5,490&nbsp;km²; [[Kazakhstan]]) #[[Bratsk Reservoir]] (5,426&nbsp;km²; [[Russia]]) #[[Lake Nasser]] (5,248&nbsp;km²; [[Egypt]], [[Sudan]]) #[[Rybinsk Reservoir]] (4,580&nbsp;km²; [[Russia]]) #[[Caniapiscau Reservoir]] (4,318&nbsp;km²; [[Canada]]) #[[Lake Guri]] (4,250&nbsp;km²; [[Venezuela]]) ===List of reservoirs by volume=== {{Cleanup-section|date=May 2008}}<!-- this list is also inaccurate, does not agree with the linked topic --> {{main|List of reservoirs by volume}} #[[Lake Kariba]] (180&nbsp;km<sup>3</sup>; [[Zimbabwe]], [[Zambia]]) #[[Bratsk Reservoir]] (169&nbsp;km<sup>3</sup>; [[Russia]]) #[[Lake Nasser]] (157&nbsp;km<sup>3</sup>; [[Egypt]], [[Sudan]]) #[[Lake Volta]] (150&nbsp;km<sup>3</sup>; [[Ghana]]) #[[Manicouagan Reservoir]] (142&nbsp;km<sup>3</sup>; [[Canada]]) #[[Lake Guri]] (135&nbsp;km<sup>3</sup>; [[Venezuela]]) #[[Williston Lake]] (74&nbsp;km<sup>3</sup>; [[Canada]]) #[[Krasnoyarsk Reservoir]] (73&nbsp;km<sup>3</sup>; [[Russia]]) #[[Zeya Reservoir]] (68 km&nbsp;<sup>3</sup>; [[Russia]]) ==Other uses== A [[water tank]] is also a reservoir, feeding into a local water system when demand is high, and refilling when it is low. Typically they are placed in a higher part of the area it serves, so the system is gravity-fed from it. A reservoir may also refer to the water for a [[steam]] [[iron]] or [[humidifier]], or collected from a [[dehumidifier]] or [[air conditioner]] (before being carried or pumped outside, respectively). The term is also used for [[perfume]]s and liquid [[air freshener]]s, as well as the [[paint]] bottle for [[airbrush]]es, or for any other [[spray]] or [[atomizer]]. ==See also== {{portalpar|Water|Drinking water.jpg}} *[[Drainage basin]] *[[Drought]] *[[Ab Anbar]] ==Notes== <references/> ==References== <!-- this is a collection of papers, cites should give the author of individual papers --> *{{citation |editor-first=John |editor-last=Rodda |editor2-first=Lucio |editor2-last=Ubertini |date=2004 |title=The Basis of Civilization &ndash; Water Science? |publisher=International Association of Hydrological Science |isbn=1-901502-57-0 }} * Wilson & Wilson (2005). ''Encyclopedia of Ancient Greece''. Routledge. ISBN 0415973341. [[Category:Reservoirs| ]] [[Category:Lakes]] [[Category:Physical infrastructure]] [[ar:خزان مائي]] [[bg:Язовир]] [[ca:Embassament]] [[cs:Přehrada]] [[da:Reservoir]] [[de:Stausee]] [[et:Veehoidla]] [[el:Τεχνητή λίμνη]] [[es:Embalse]] [[fr:Lac de barrage]] [[zh-classical:溜池]] [[id:Waduk]] [[it:Lago artificiale]] [[nl:Stuwmeer]] [[ja:ため池]] [[no:Kunstig innsjø]] [[pl:Zbiornik retencyjny]] [[pt:Lago artificial]] [[ro:Lac de acumulare]] [[qu:Hark'a qucha]] [[ru:Водохранилище]] [[fi:Tekojärvi]] [[uk:Водосховище]] [[zh:水庫]]