79-680: Lake Karapiro ( Māori : Karāpiro ) is an artificial reservoir lake on the Waikato River at Karapiro , 8 kilometres (5.0 mi) south-east of Cambridge in New Zealand's North Island . The lake was formed in 1947 by the damming of the Waikato River to store water for the 96-megawatt Karapiro power station . The lake is also one of two premier rowing venues in New Zealand (alongside Lake Ruataniwha in Canterbury) and
158-537: A block for migrating fish, trapping them in one area, producing food and a habitat for various water-birds. They can also flood various ecosystems on land and may cause extinctions. Creating reservoirs can alter the natural biogeochemical cycle of mercury . After a reservoir's initial formation, there is a large increase in the production of toxic methylmercury (MeHg) via microbial methylation in flooded soils and peat. MeHg levels have also been found to increase in zooplankton and in fish. Dams can severely reduce
237-815: A chain up the valley. Coastal reservoirs are fresh water storage reservoirs located on the sea coast near a river mouth to store the flood water of a river. As the land-based reservoir construction is fraught with substantial land submergence, coastal reservoirs are preferred economically and technically since they do not use scarce land area. Many coastal reservoirs were constructed in Asia and Europe. Saemanguem in South Korea, Marina Barrage in Singapore, Qingcaosha in China, and Plover Cove in Hong Kong are
316-658: A conventional oil-fired thermal generation plant. For instance, In 1990, the impoundment behind the Balbina Dam in Brazil (inaugurated in 1987) had over 20 times the impact on global warming than would generating the same power from fossil fuels, due to the large area flooded per unit of electricity generated. Another study published in the Global Biogeochemical Cycles also found that newly flooded reservoirs released more carbon dioxide and methane than
395-533: A drop of water seep into the ocean without benefiting mankind." He created the reservoir named Parakrama Samudra ("sea of King Parakrama"). Vast artificial reservoirs were also built by various ancient kingdoms in Bengal, Assam, and Cambodia. Many dammed river reservoirs and most bank-side reservoirs are used to provide the raw water feed to a water treatment plant which delivers drinking water through water mains. The reservoir does not merely hold water until it
474-525: A few such coastal reservoirs. Where water is pumped or siphoned from a river of variable quality or size, bank-side reservoirs may be built to store the water. Such reservoirs are usually formed partly by excavation and partly by building a complete encircling bund or embankment , which may exceed 6 km (4 miles) in circumference. Both the floor of the reservoir and the bund must have an impermeable lining or core: initially these were often made of puddled clay , but this has generally been superseded by
553-455: A high-level reservoir is filled with water using high-performance electric pumps at times when electricity demand is low, and then uses this stored water to generate electricity by releasing the stored water into a low-level reservoir when electricity demand is high. Such systems are called pump-storage schemes. Reservoirs can be used in a number of ways to control how water flows through downstream waterways: Reservoirs can be used to balance
632-570: A loss in both quantity and quality of water necessary for maintaining ecological balance and pose a risk of increasing severity and duration of droughts due to climate change. In summary, they consider it a misadaptation to climate change. Proponents of reservoirs or substitution reserves, on the other hand, see them as a solution for sustainable agriculture while waiting for a truly durable agricultural model. Without such reserves, they fear that unsustainable imported irrigation will be inevitable. They believe that these reservoirs should be accompanied by
711-628: A markedly more swollen, pointed and protruding umbo . This clam originally occurs in freshwater environments of Eastern Asia, including Russia , Thailand , the Philippines , China , Taiwan , Korea , and Japan . C. fluminea also occurs naturally in freshwater environments of Africa . Many coastal rivers with a heavy industrial shipping presence in the invaded range of C. fluminea sustain Asian clam populations. Various non-indigenous populations of C. fluminea include: Human activities are
790-419: A narrow valley or canyon may cover relatively little vegetation, while one situated on a plain may flood a great deal of vegetation. The site may be cleared of vegetation first or simply flooded. Tropical flooding can produce far more greenhouse gases than in temperate regions. The following table indicates reservoir emissions in milligrams per square meter per day for different bodies of water. Depending upon
869-611: A reservoir is called the "conservation pool". In the United Kingdom, "top water level" describes the reservoir full state, while "fully drawn down" describes the minimum retained volume. There is a wide variety of software for modelling reservoirs, from the specialist Dam Safety Program Management Tools (DSPMT) to the relatively simple WAFLEX , to integrated models like the Water Evaluation And Planning system (WEAP) that place reservoir operations in
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#1732791139251948-740: A river valley, with the potential to wash away towns and villages and cause considerable loss of life, such as the devastation following the failure of containment at Llyn Eigiau which killed 17 people. (see also List of dam failures ) A notable case of reservoirs being used as an instrument of war involved the British Royal Air Force Dambusters raid on Germany in World War II (codenamed " Operation Chastise " ), in which three German reservoir dams were selected to be breached in order to damage German infrastructure and manufacturing and power capabilities deriving from
1027-399: A successful invasive species throughout the world, including North America, South America, Europe, and New Zealand. It is native to freshwater environments of Eastern Asia, including Russia , Thailand , the Philippines , China , Taiwan , Korea , and Japan . C. fluminea also occurs naturally in freshwater environments of Africa . Corbicula fluminea is commonly known in the west as
1106-582: A territorial project that unites all water stakeholders with the goal of preserving and enhancing natural environments. Two main types of reservoirs can be distinguished based on their mode of supply. Circa 3000 BC, the craters of extinct volcanoes in Arabia were used as reservoirs by farmers for their irrigation water. Dry climate and water scarcity in India led to early development of stepwells and other water resource management techniques, including
1185-466: Is a species of freshwater clam , an aquatic bivalve mollusk in the family Cyrenidae . C. fluminea is often confused with Corbicula fluminalis due to the two species' similar color and texture. Two species may be present in some introduced populations: C. fluminea and C. fluminalis . The names themselves are sometimes confused in the literature (e.g. by being called "Corbicula fluminata" ). The ratio of width and height in C. fluminea
1264-476: Is a natural lake whose level was raised by a low dam and into which the River Dee flows or discharges depending upon flow conditions, as part of the River Dee regulation system . This mode of operation is a form of hydraulic capacitance in the river system. Many reservoirs often allow some recreational uses, such as fishing and boating . Special rules may apply for the safety of the public and to protect
1343-422: Is a self-fertile simultaneous hermaphrodite which can broadcast spawn up to 570 mucoid larvae per day per individual, and more than 68,000 per year per individual. Larvae are ~200 microns in length when discharged from an adult and dispersed through water until becoming sessile adults. Adults can reach a length of about 5 centimetres (2.0 in). Corbicula fluminea is an active suspension feeder, and in
1422-484: Is a water reservoir for agricultural use. They are filled using pumped groundwater , pumped river water or water runoff and are typically used during the local dry season. This type of infrastructure has sparked an opposition movement in France, with numerous disputes and, for some projects, protests, especially in the former Poitou-Charentes region where violent demonstrations took place in 2022 and 2023. In Spain, there
1501-437: Is also used technically to refer to certain forms of liquid storage, such the "coolant reservoir" that captures overflow of coolant in an automobile's cooling system. Dammed reservoirs are artificial lakes created and controlled by a dam constructed across a valley and rely on the natural topography to provide most of the basin of the reservoir. These reservoirs can either be on-stream reservoirs , which are located on
1580-399: Is an enlarged lake behind a dam , usually built to store fresh water , often doubling for hydroelectric power generation . Reservoirs are created by controlling a watercourse that drains an existing body of water, interrupting a watercourse to form an embayment within it, excavating, or building any number of retaining walls or levees to enclose any area to store water. The term
1659-448: Is common in the aquarium trade and can be intentionally or unintentionally released in the wild by aquarists. Corbicula fluminea enjoys several physiological capabilities which are advantageous in promoting its invasion of novel lentic / lotic environments including: Corbicula fluminea is a self-fertilizing, simultaneous hermaphrodite which can asexually produce internally-brooded, semi-buoyant planktonic larvae when spermiogenesis
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#17327911392511738-710: Is considered not safe to eat, as caused by pollution in the river. Corbicula is a successful breeder in the rivers and lakes of many countries in the world, breeding densely in localized water, and transported elsewhere via water currents or by the movement of humans and their waterborne apparatus. This allows them to outcompete against native invertebrates, including mollusks such as mussels, for phytoplankton as food. Corbicula has shown to interfere with water-based infrastructure created by humans, such as water treatment and hydroelectric dams, by clogging them up. Right after reaching maturity, these clams produce eggs, followed by sperm. Throughout adult life, Corbicula
1817-501: Is greater acceptance because all beneficiary users are involved in the implementation of the system. The specific debate about substitution reservoirs is part of a broader discussion related to reservoirs used for agricultural irrigation, regardless of their type, and a certain model of intensive agriculture. Opponents view these reservoirs as a monopolization of resources benefiting only a few, representing an outdated model of productive agriculture. They argue that these reservoirs lead to
1896-677: Is induced at temperatures above 10 °C (50 °F). This allows C. fluminea to colonize novel habitats at an advanced rate. Studies on which abiotic habitat characteristics are most strongly associated with Asian clam population abundance have produced varying results. Brazilian habitats have been found to have support the largest abundances of invasive Corbicula spp. in areas with coarser dominant sediment fractions, while negatively correlated with increasing levels of organic matter. Others studies have shown abiotic habitat characteristics such as water redox potential, inorganic nutrient content, hardness, and organic matter content in tandem with
1975-466: Is needed: it can also be the first part of the water treatment process. The time the water is held before it is released is known as the retention time . This is a design feature that allows particles and silts to settle out, as well as time for natural biological treatment using algae , bacteria and zooplankton that naturally live in the water. However natural limnological processes in temperate climate lakes produce temperature stratification in
2054-536: Is now used by the Aquarius Golf Club. Service reservoirs perform several functions, including ensuring sufficient head of water in the water distribution system and providing water capacity to even-out peak demand from consumers, enabling the treatment plant to run at optimum efficiency. Large service reservoirs can also be managed to reduce the cost of pumping by refilling the reservoir at times of day when energy costs are low. An irrigation reservoir
2133-424: Is on average 1.1. In C. fluminalis it is smaller (0.97); still, there is much variation and considerable overlap in shape. Most easily, they can be distinguished by the number of ribs on the shell; C. fluminea has 7 to 14 ribs per cm, C. fluminalis 13 to 28. This character is already clearly recognizable (albeit only by direct comparison) in very small (5 mm diameter) specimens. In addition, when viewed from
2212-419: Is stored in the reservoir. Any excess water can be spilled via a specifically designed spillway. Stored water may be piped by gravity for use as drinking water , to generate hydro-electricity or to maintain river flows to support downstream uses. Occasionally reservoirs can be managed to retain water during high rainfall events to prevent or reduce downstream flooding. Some reservoirs support several uses, and
2291-480: Is the base for the country's high-performance rowing programme. In about 1600, Te Ihingarangi built a pā (fortified village) called Te Tiki o Ihingarangi near where Lake Karapiro is today. In 1830 Ngāti Hauā defeated Ngāti Maru in a battle at Taumatawīwī, two kilometres south of Karapiro Domain. On the orders of the Ngāti Hauā chief Te Waharoa , his dead warriors were cremated, this taking place on rocks beside
2370-473: Is the portion of the reservoir that can be used for flood control, power production, navigation , and downstream releases. In addition, a reservoir's "flood control capacity" is the amount of water it can regulate during flooding. The "surcharge capacity" is the capacity of the reservoir above the spillway crest that cannot be regulated. In the United States, the water below the normal maximum level of
2449-623: The Asian clam , Asiatic clam , or Asian gold clam . In Southeast Asia, C. fluminea is known as the golden clam , prosperity clam , pygmy clam , or good luck clam . In New Zealand, it is commonly referred as the freshwater gold clam . Right and left valve of the same specimen: Corbicula have had global success as an aquatic invasive species , having been introduced to a novel range including South America , North America and Europe . Human industrial activity, such as transport of larvae via ballast water in container ships, has been noted in
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2528-452: The Ruhr and Eder rivers. The economic and social impact was derived from the enormous volumes of previously stored water that swept down the valleys, wreaking destruction. This raid later became the basis for several films. All reservoirs will have a monetary cost/benefit assessment made before construction to see if the project is worth proceeding with. However, such analysis can often omit
2607-653: The prismatic layer visible through the proteinous outer layer. The periostracum can flake, allowing the white prismatic layer to show through. The shells exhibit a light purple nacre on the inside. As a filter feeder , Corbicula strains suspended contents of nearby water and absorbing material to feed itself. Large quantities of toxins are absorbed in their gut, accumulating high concentrations of toxins. The clams excrete large quantities of inorganic chemicals, such as nitrogen and phosphorus, after feeding off sediment. Despite edibility of Corbicula in native countries, Coribicula sourced from New Zealand's Waikato River
2686-673: The 1800s, most of which are lined with brick. A good example is the Honor Oak Reservoir in London, constructed between 1901 and 1909. When it was completed it was said to be the largest brick built underground reservoir in the world and it is still one of the largest in Europe. This reservoir now forms part of the southern extension of the Thames Water Ring Main . The top of the reservoir has been grassed over and
2765-731: The Meroitic town of Butana . The Hafirs catch the water during rainy seasons in order to ensure water is available for several months during dry seasons to supply drinking water, irrigate fields and water cattle. The Great Reservoir near the Lion Temple in Musawwarat es-Sufra is a notable hafir in Kush. In Sri Lanka , large reservoirs were created by ancient Sinhalese kings in order to store water for irrigation. The famous Sri Lankan king Parākramabāhu I of Sri Lanka said "Do not let
2844-488: The Ministry of Primary Industries, the clams have likely populated in the river for several years prior to discovery. Based on patterns of unsuccessful eradication of Corbicula overseas, eradication of Corbicula is predicted to be near-impossible in New Zealand. They have been blamed for algal blooms and concerns exist they will outcompete and displace native species such as the montane pea clam ( Pisidium spp.) and
2923-488: The US. The capacity, volume, or storage of a reservoir is usually divided into distinguishable areas. Dead or inactive storage refers to water in a reservoir that cannot be drained by gravity through a dam's outlet works , spillway, or power plant intake and can only be pumped out. Dead storage allows sediments to settle, which improves water quality and also creates an area for fish during low levels. Active or live storage
3002-527: The Waikato River, the location then becoming known as Karāpiro , from the Māori language words karā , meaning "basaltic stone", and piro , meaning "foul smelling". The site was flooded when the lake created. The ten-megawatt Horahora Power Station , 13 km upstream of Karapiro Dam was also flooded with the formation of Lake Karapiro. Construction of the Karapiro Dam began in 1940, however progress
3081-401: The Waikato River. Water taken from the lake is passed through three Kaplan turbines in the powerhouse, before being deposited into the lower Waikato River. Each turbine turns a 32 MW generator, and the electricity from the generators is fed into Transpower 's national grid . The station is a base load generator due to its need to maintain water flows into the Waikato River system beyond
3160-400: The amount of very coarse sand combine to explain 59.3% of Corbicula population habitat association via statistical tests. Asian clam invasions seem to be limited by elevation (88% of the invaded range is below 500m elevation ), latitude (90% lies between latitudes 30°and 55° ) as well as the minimum winter temperature (−10 °C (14 °F)) of the ecosystem. Corbicula fluminea reworks
3239-471: The amount of water reaching countries downstream of them, causing water stress between the countries, e.g. the Sudan and Egypt , which damages farming businesses in the downstream countries, and reduces drinking water. Corbicula fluminea Tellina fluminea O. F. Müller, 1774 (original combination) Corbicula fluminea is a species of freshwater clam native to eastern Asia which has become
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3318-535: The area flooded versus power produced, a reservoir built for hydro- electricity generation can either reduce or increase the net production of greenhouse gases when compared to other sources of power. A study for the National Institute for Research in the Amazon found that hydroelectric reservoirs release a large pulse of carbon dioxide from decay of trees left standing in the reservoirs, especially during
3397-428: The base of the dam or some distance away. In a flat river valley a reservoir needs to be deep enough to create a head of water at the turbines; and if there are periods of drought the reservoir needs to hold enough water to average out the river's flow throughout the year(s). Run-of-the-river hydro in a steep valley with constant flow needs no reservoir. Some reservoirs generating hydroelectricity use pumped recharge:
3476-556: The building of a reservoir at Girnar in 3000 BC. Artificial lakes dating to the 5th century BC have been found in ancient Greece. The artificial Bhojsagar lake in present-day Madhya Pradesh state of India, constructed in the 11th century, covered 650 square kilometres (250 sq mi). The Kingdom of Kush invented the Hafir , a type of reservoir, during the Meroitic period . 800 ancient and modern hafirs have been registered in
3555-465: The chief reason for the wide dispersal of C. fluminea as an invasive aquatic organism. Its global invasion probably started with Asian immigration in North America during the 1920s, as it was used as food source by these communities. Corbicula fluminea , along with other exotic bivalve larvae, may be accidentally transported via ballast water or recreational boaters. Furthermore, the species
3634-442: The context of system-wide demands and supplies. In many countries large reservoirs are closely regulated to try to prevent or minimize failures of containment. While much of the effort is directed at the dam and its associated structures as the weakest part of the overall structure, the aim of such controls is to prevent an uncontrolled release of water from the reservoir. Reservoir failures can generate huge increases in flow down
3713-561: The dam located at the narrowest practical point to provide strength and the lowest cost of construction. In many reservoir construction projects, people have to be moved and re-housed, historical artifacts moved or rare environments relocated. Examples include the temples of Abu Simbel (which were moved before the construction of the Aswan Dam to create Lake Nasser from the Nile in Egypt ),
3792-460: The developed world Naturally occurring lakes receive organic sediments which decay in an anaerobic environment releasing methane and carbon dioxide . The methane released is approximately 8 times more potent as a greenhouse gas than carbon dioxide. As a human-made reservoir fills, existing plants are submerged and during the years it takes for this matter to decay, will give off considerably more greenhouse gases than lakes do. A reservoir in
3871-507: The downstream river to maintain river quality, support fisheries, to maintain downstream industrial and recreational uses or for a range of other purposes. Such releases are known as compensation water . The units used for measuring reservoir areas and volumes vary from country to country. In most of the world, reservoir areas are expressed in square kilometers; in the United States, acres are commonly used. For volume, either cubic meters or cubic kilometers are widely used, with acre-feet used in
3950-440: The environmental impacts of dams and the reservoirs that they contain. Some impacts, such as the greenhouse gas production associated with concrete manufacture, are relatively easy to estimate. Other impacts on the natural environment and social and cultural effects can be more difficult to assess and to weigh in the balance but identification and quantification of these issues is now commonly required in major construction projects in
4029-499: The first decade after flooding. This elevates the global warming impact of the dams to levels much higher than would occur by generating the same power from fossil fuels . According to the World Commission on Dams report (Dams And Development), when the reservoir is relatively large and no prior clearing of forest in the flooded area was undertaken, greenhouse gas emissions from the reservoir could be higher than those of
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#17327911392514108-413: The flow in highly managed systems, taking in water during high flows and releasing it again during low flows. In order for this to work without pumping requires careful control of water levels using spillways . When a major storm approaches, the dam operators calculate the volume of water that the storm will add to the reservoir. If forecast storm water will overfill the reservoir, water is slowly let out of
4187-425: The growth of algae and cyanobacteria, as a byproduct of the excretion of these clams. Corbicula has also been shown to profoundly influence community dynamics within the macrobenthos of invaded systems. Corbicula has been shown to remove as much as 70% of phytoplankton biomass in reaches of invaded rivers with a robust clam population. The clam has also been reported as causing a decline of dissolved oxygen in
4266-580: The hydroelectric reservoirs there do emit greenhouse gases, it is on a much smaller scale than thermal power plants of similar capacity. Hydropower typically emits 35 to 70 times less greenhouse gases per TWh of electricity than thermal power plants. A decrease in air pollution occurs when a dam is used in place of thermal power generation, since electricity produced from hydroelectric generation does not give rise to any flue gas emissions from fossil fuel combustion (including sulfur dioxide , nitric oxide and carbon monoxide from coal ). Dams can produce
4345-531: The lake in 1949. Since the 1980s, Lake Karapiro alternates with the South Island's Lake Ruataniwha in hosting the New Zealand national rowing championships and the New Zealand secondary school rowing championships ( Maadi Cup ). Rowers who train on the lake mostly live in nearby Cambridge . An International Rowing Federation inspection panel visited Lake Karapiro in March 2006 and said in its report that it
4424-533: The lake. Lake Karapiro is infested with hornwort, a submerged macrophyte from North America that is ranked as the worst submerged macrophyte in New Zealand. This plant is an unwanted organism under the Biosecurity Act 1993 . More recently, the lake was the first site where gold clams were detected in New Zealand, in May 2023. The gold clam grows and breeds very quickly, and can alter an ecosystem by reducing
4503-432: The landscape is relatively flat. Other service reservoirs can be storage pools, water tanks or sometimes entirely underground cisterns , especially in more hilly or mountainous country. Modern reserviors will often use geomembrane liners on their base to limit seepage and/or as floating covers to limit evaporation, particularly in arid climates. In the United Kingdom, Thames Water has many underground reservoirs built in
4582-588: The literature as a chief invasion vector. A market exists for Asian clams for human consumption in Japan, China, and other countries in the region. According to the United States Geological Survey , C. fluminea is likely to continue to expand its North American range until it reaches the maximum extent of its low temperature tolerance. The periostracum of the shell is normally yellow-green, brown, or black with concentric growth rings of
4661-506: The majority of the phytoplankton, excreting a lot of nitrogen and phosphorus, and physically dominating the available space on the river or lakebed. Despite this, the lake is still open for recreation, making it a threat to other waterways because people may unknowingly spread golden clams on their watercrafts. It has been added to the unwanted organism register. Reservoir A reservoir ( / ˈ r ɛ z ər v w ɑːr / ; from French réservoir [ʁezɛʁvwaʁ] )
4740-470: The modern use of rolled clay. The water stored in such reservoirs may stay there for several months, during which time normal biological processes may substantially reduce many contaminants and reduce turbidity . The use of bank-side reservoirs also allows water abstraction to be stopped for some time, for instance when the river is unacceptably polluted or when flow conditions are very low due to drought . The London water supply system exhibits one example of
4819-609: The new top water level exceeds the watershed height on one or more of the feeder streams such as at Llyn Clywedog in Mid Wales . In such cases additional side dams are required to contain the reservoir. Where the topography is poorly suited to forming a single large reservoir, a number of smaller reservoirs may be constructed in a chain, as in the River Taff valley where the Llwyn-on , Cantref and Beacons Reservoirs form
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#17327911392514898-415: The operating rules may be complex. Most modern reservoirs have a specially designed draw-off tower that can discharge water from the reservoir at different levels, both to access water as the water level falls, and to allow water of a specific quality to be discharged into the downstream river as "compensation water": the operators of many upland or in-river reservoirs have obligations to release water into
4977-428: The original streambed of the downstream river and are filled by creeks , rivers or rainwater that runs off the surrounding forested catchments, or off-stream reservoirs , which receive diverted water from a nearby stream or aqueduct or pipeline water from other on-stream reservoirs. Dams are typically located at a narrow part of a downstream of a natural basin. The valley sides act as natural walls, with
5056-481: The pre-flooded landscape, noting that forest lands, wetlands, and preexisting water features all released differing amounts of carbon dioxide and methane both pre- and post-flooding. The Tucuruí Dam in Brazil (completed in 1984) had only 0.4 times the impact on global warming than would generating the same power from fossil fuels. A two-year study of carbon dioxide and methane releases in Canada concluded that while
5135-427: The process of feeding by pumping water through its body (as well as feeding on interstitial sedimentary material via pedal feeding when suspended grazing items are limited). They feed primarily on phytoplankton ( algae ), which they actively filter out the water, but may pedal feed on organic matter in the sandy or muddy bottoms of streams, lakes, or canals where the clam establishes a population. Corbicula fluminea
5214-437: The quality of the water and the ecology of the surrounding area. Many reservoirs now support and encourage less formal and less structured recreation such as natural history , bird watching , landscape painting , walking and hiking , and often provide information boards and interpretation material to encourage responsible use. Water falling as rain upstream of the reservoir, together with any groundwater emerging as springs,
5293-598: The ramshorn snail ( Planorbidae ). Efforts are underway at Lake Tahoe to smother the clams on the bottom with rubber mats. In August 2020 routine inspections in Wyoming found several watercraft to be heavily infested including one with C. fluminea . On October 16, 2020, the Montana Department of Fish, Wildlife and Parks recommended that Lake Elmo — in Billings — be drained to dry out and freeze to death
5372-464: The relocation of the village of Capel Celyn during the construction of Llyn Celyn , and the relocation of Borgo San Pietro of Petrella Salto during the construction of Lake Salto . Construction of a dammed reservoir will usually require the river to be diverted during part of the build, often through a temporary tunnel or by-pass channel. In hilly regions, reservoirs are often constructed by enlarging existing lakes. Sometimes in such reservoirs,
5451-638: The reservoir prior to, and during, the storm. If done with sufficient lead time, the major storm will not fill the reservoir and areas downstream will not experience damaging flows. Accurate weather forecasts are essential so that dam operators can correctly plan drawdowns prior to a high rainfall event. Dam operators blamed a faulty weather forecast on the 2010–2011 Queensland floods . Examples of highly managed reservoirs are Burrendong Dam in Australia and Bala Lake ( Llyn Tegid ) in North Wales . Bala Lake
5530-682: The scientific literature in the Western Hemisphere was of its introduction into British Columbia circa 1924, followed by a spread throughout the Pacific Northwest and across the American south through South America. Invasions in Europe and Central America were more recent, first appearing in Caribbean countries in 1998. Corbicula was discovered in New Zealand along a stretch of the Waikato River in May 2023. According to
5609-407: The sediments it resides on through the process of bioturbation . Asian clams are considered biodiffusors similar to marine clam species due to their observed bioturbation activity which may negatively affect other members of the benthic community in invaded areas. Excessive excretion of inorganic chemicals such as nitrogen and phosphorus imbalance concentrations of oxygen in the water, encouraging
5688-499: The use of bank-side storage: here water is taken from the River Thames and River Lee into several large Thames-side reservoirs, such as Queen Mary Reservoir that can be seen along the approach to London Heathrow Airport . Service reservoirs store fully treated potable water close to the point of distribution. Many service reservoirs are constructed as water towers , often as elevated structures on concrete pillars where
5767-400: The ventral side (looking at the opening between the shells), C. fluminalis is rounder, almost heart-shaped, while C. fluminea has a slightly flatter shape like a teardrop with a notched broad end. Small specimens of C. fluminalis are almost spherical, while those of C. fluminea are decidedly flattened. All these differences except the rib number are a consequence of C. fluminalis having
5846-463: The water of the same river system with wide-ranging second-order effects. The primary economic and social impact of the invasion of C. fluminea has been billions of dollars in costs associated with clogged plumbing and, heat exchangers, or other human-created infrastructure. Ecologically, C. fluminea contributes to declines and replacement of highly vulnerable, already threatened native clams. The first recorded instance of Corbicula presence in
5925-412: The water, which tends to partition some elements such as manganese and phosphorus into deep, cold anoxic water during the summer months. In the autumn and winter the lake becomes fully mixed again. During drought conditions, it is sometimes necessary to draw down the cold bottom water, and the elevated levels of manganese in particular can cause problems in water treatment plants. In 2005, about 25% of
6004-476: The world's 33,105 large dams (over 15 metres in height) were used for hydroelectricity. The U.S. produces 3% of its electricity from 80,000 dams of all sizes. An initiative is underway to retrofit more dams as a good use of existing infrastructure to provide many smaller communities with a reliable source of energy. A reservoir generating hydroelectricity includes turbines connected to the retained water body by large-diameter pipes. These generating sets may be at
6083-484: Was one of the fairest courses in the world they had seen and that the lake was one of the most picturesque in the world. The lake hosted the 2010 Rowing World Championships. The purpose-built Sir Don Rowlands Centre was completed in June 2010, prior to the event. The 96-megawatt Karapiro Power Station is located adjacent to the dam at the head of the lake, and is the eighth and last hydroelectric power station located on
6162-406: Was slow due to labour and material shortages related to World War II. The dam was completed in early 1947, four years behind schedule. Due to the post-war electricity shortages, the filling of Lake Karapiro had to be coordinated to minimise the time between Horahora's decommissioning and Karapiro's commissioning. The lake level reached Horahora on 4 April 1947 upon which Horahora stopped generating and
6241-555: Was submerged. The lake was sufficiently filled on 10 April 1947 to allow the first turbine-generator at Karapiro to enter service. The lake, regarded as one of New Zealand's best rowing venues, hosted the World Rowing Championships in 1978 and 2010 , as well as the rowing events for the 1950 British Empire Games . The national rowing championships, then called the Dominion championships, were first held on
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