121-800: The Elan Valley Reservoirs ( Welsh : Cronfeydd Cwm Elan ) are a chain of man-made lakes created from damming the Elan and Claerwen rivers within the Elan Valley in Mid Wales . The reservoirs, which were built by the Birmingham Corporation Water Department , provide clean drinking water for Birmingham in the West Midlands of England. The five lakes are known as the Claerwen , Craig-goch, Pen-y-garreg, Garreg-ddu, and Caban-coch. Water from
242-474: A gravity feed with a gradient of 1 in 2,300. The schedule for the project was to build the four lower Elan Valley dams first. The Claerwen would then be built later (work was expected to begin in 1939 but was delayed by the Second World War ; it was completed in 1952). The Elan Valley Railway , which was a standard-gauge line, was built by Birmingham Corporation especially for the project. It ran through
363-441: A Welsh Language Scheme, which indicates its commitment to the equality of treatment principle. This is sent out in draft form for public consultation for a three-month period, whereupon comments on it may be incorporated into a final version. It requires the final approval of the now defunct Welsh Language Board ( Bwrdd yr Iaith Gymraeg ). Thereafter, the public body is charged with implementing and fulfilling its obligations under
484-586: A Welsh-language edge inscription was used on pound coins dated 1985, 1990 and 1995, which circulated in all parts of the UK prior to their 2017 withdrawal. The wording is Pleidiol wyf i'm gwlad (Welsh for 'True am I to my country'), and derives from the national anthem of Wales, " Hen Wlad Fy Nhadau ". UK banknotes are in English only. Some shops employ bilingual signage. Welsh sometimes appears on product packaging or instructions. The UK government has ratified
605-537: 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
726-647: A census glossary of terms to support the release of results from the census, including their definition of "main language" as referring to "first or preferred language" (though that wording was not in the census questionnaire itself). The wards in England with the most people giving Welsh as their main language were the Liverpool wards of Central and Greenbank ; and Oswestry South in Shropshire . The wards of Oswestry South (1.15%), Oswestry East (0.86%) and St Oswald (0.71%) had
847-791: 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
968-517: A church (which was replaced with Nantgwyllt Church ). Only landowners were given compensation. Work began to construct the reservoirs the following year in 1893. Construction was overseen by James Mansergh, on behalf of the City of Birmingham's Water Department . Due to the height above sea level of the Elan Valley, water would be fed to Birmingham along a 116-kilometre (72 mi) pipeline that employed
1089-636: 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
1210-546: A day. Following the completion of the lower dams, the entire Elan Valley Railway had been entirely lifted by 1916. Road transport was used when the Claerwen dam was built in the late 1940s and 1950s. The railway was required because the core of the Caban-coch, Pen-y-garreg and Craig-goch dams were built from large irregular stone blocks ("plums") embedded in concrete. The rock was mined locally from Cigfran and Craig-cnwch quarries by
1331-529: 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
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#17330851493681452-525: 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
1573-455: 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
1694-570: 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
1815-419: 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
1936-521: A potential total capacity of nearly 100,000 megalitres . The dams and reservoirs are: In addition to the four main dams, there are three other dams at the site: The Elan dam scheme was developed in the 19th century following rapid growth of the population of Birmingham due to the Industrial Revolution . The city's expansion resulted in regular outbreaks of water-borne diseases and major epidemics such as typhoid , cholera and dysentery due to
2057-592: 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
2178-720: 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
2299-479: A single discourse (known in linguistics as code-switching ). Welsh speakers are largely concentrated in the north and west of Wales, principally Gwynedd , Conwy County Borough , Denbighshire , Anglesey , Carmarthenshire , north Pembrokeshire , Ceredigion , parts of Glamorgan , and north-west and extreme south-west Powys . However, first-language and other fluent speakers can be found throughout Wales. Welsh-speaking communities persisted well into
2420-402: A terrace house with eight single men. A school was provided for under-11-year-olds, who were expected to work on attaining that age. The camp also had a hospital for injuries, an isolation hospital for infectious cases, and a bath house. Men were allowed to drink beer at a pub, though women were not. Other facilities included a library, public hall, shop and canteen. Electric street lighting in
2541-574: 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
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#17330851493682662-995: Is a Celtic language of the Brittonic subgroup that is native to the Welsh people . Welsh is spoken natively in Wales , by some in England , and in Y Wladfa (the Welsh colony in Chubut Province , Argentina ). It is spoken by smaller numbers of people in Canada and the United States descended from Welsh immigrants, within their households (especially in Nova Scotia ). Historically, it has also been known in English as "British", "Cambrian", "Cambric" and "Cymric". The Welsh Language (Wales) Measure 2011 gave
2783-471: 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
2904-480: 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
3025-437: 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
3146-399: 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
3267-656: Is available throughout Europe on satellite and online throughout the UK. Since the digital switchover was completed in South Wales on 31 March 2010, S4C Digidol became the main broadcasting channel and fully in Welsh. The main evening television news provided by the BBC in Welsh is available for download. There is also a Welsh-language radio station, BBC Radio Cymru , which was launched in 1977. Reservoir (water) A reservoir ( / ˈ r ɛ z ər v w ɑːr / ; from French réservoir [ʁezɛʁvwaʁ] )
3388-667: Is considered to have lasted from then until the 14th century, when the Modern Welsh period began, which in turn is divided into Early and Late Modern Welsh. The word Welsh is a descendant, via Old English wealh, wielisc , of the Proto-Germanic word * Walhaz , which was derived from the name of the Celtic people known to the Romans as Volcae and which came to refer to speakers of Celtic languages, and then indiscriminately to
3509-501: 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
3630-466: 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
3751-528: 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
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3872-419: 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
3993-505: Is the label attached to the Welsh of the 12th to 14th centuries, of which much more remains than for any earlier period. This is the language of nearly all surviving early manuscripts of the Mabinogion , although the tales themselves are certainly much older. It is also the language of the existing Welsh law manuscripts. Middle Welsh is reasonably intelligible to a modern-day Welsh speaker. The Bible translations into Welsh helped maintain
4114-410: 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
4235-704: The Cynfeirdd or "Early Poets" – is generally considered to date to the Primitive Welsh period. However, much of this poetry was supposedly composed in the Hen Ogledd , raising further questions about the dating of the material and language in which it was originally composed. This discretion stems from the fact that Cumbric was widely believed to have been the language used in Hen Ogledd. An 8th-century inscription in Tywyn shows
4356-494: The 2016 Australian census , 1,688 people noted that they spoke Welsh. In the 2011 Canadian census , 3,885 people reported Welsh as their first language . According to the 2021 Canadian census , 1,130 people noted that Welsh was their mother tongue. The 2018 New Zealand census noted that 1,083 people in New Zealand spoke Welsh. The American Community Survey 2009–2013 noted that 2,235 people aged five years and over in
4477-461: The 2021 census , 7,349 people in England recorded Welsh to be their "main language". In the 2011 census, 1,189 people aged three and over in Scotland noted that Welsh was a language (other than English) that they used at home. It is believed that there are as many as 5,000 speakers of Patagonian Welsh . In response to the question 'Does the person speak a language other than English at home?' in
4598-525: The European Charter for Regional or Minority Languages in respect of Welsh. The language has greatly increased its prominence since the creation of the television channel S4C in November 1982, which until digital switchover in 2010 broadcast 70 per cent of Channel 4's programming along with a majority of Welsh language shows during peak viewing hours. The all-Welsh-language digital station S4C Digidol
4719-727: The Polish name for Italians) have a similar etymology. The Welsh term for the language, Cymraeg , descends from the Brythonic word combrogi , meaning 'compatriots' or 'fellow countrymen'. Welsh evolved from Common Brittonic , the Celtic language spoken by the ancient Celtic Britons . Classified as Insular Celtic , the British language probably arrived in Britain during the Bronze Age or Iron Age and
4840-448: 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
4961-618: The United States spoke Welsh at home. The highest number of those (255) lived in Florida . Sources: Calls for the Welsh language to be granted official status grew with the establishment of the nationalist political party Plaid Cymru in 1925, the establishment of the Welsh Language Society in 1962 and the rise of Welsh nationalism in the later 20th century. Of the six living Celtic languages (including two revived), Welsh has
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5082-686: The Ystwyth valley. This scheme would have created a huge reservoir dwarfing all others in Mid Wales, and flooding miles of wild upland valleys. The proposals were eventually abandoned in the face of reducing projections for industrial water demand and an increasing awareness of the environmental issues that such an expansion might create. 52°16′20″N 3°41′20″W / 52.27222°N 3.68889°W / 52.27222; -3.68889 Welsh language Welsh ( Cymraeg [kəmˈraːiɡ] or y Gymraeg [ə ɡəmˈraːiɡ] )
5203-466: The reservoirs is carried by gravity to Frankley Reservoir in Birmingham via the Elan aqueduct . Pumping is not required because the network drops 52 metres (171 ft) along its 73-mile (117 km) length from its source to Frankley . A gradient of 1:2,300 maintains a flow of less than 2 miles per hour (3.2 km/h); water takes one and a half to two days to reach Birmingham. The aqueduct, which
5324-573: The "hugely important role", adding, "I look forward to working with the Welsh Government and organisations in Wales in developing the new system of standards. I will look to build on the good work that has been done by the Welsh Language Board and others to strengthen the Welsh language and ensure that it continues to thrive." First Minister Carwyn Jones said that Huws would act as a champion for
5445-646: 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
5566-589: The 1880s identified a small part of Shropshire as still then speaking Welsh, with the "Celtic Border" passing from Llanymynech through Oswestry to Chirk . The number of Welsh-speaking people in the rest of Britain has not yet been counted for statistical purposes. In 1993, the Welsh-language television channel S4C published the results of a survey into the numbers of people who spoke or understood Welsh, which estimated that there were around 133,000 Welsh-speaking people living in England, about 50,000 of them in
5687-522: The 1993 Act nor secondary legislation made under it covers the private sector, although some organisations, notably banks and some railway companies, provide some of their information in Welsh. On 7 December 2010, the Welsh Assembly unanimously approved a set of measures to develop the use of the Welsh language within Wales. On 9 February 2011 this measure, the Welsh Language (Wales) Measure 2011 ,
5808-481: The Assembly which confirms the official status of the Welsh language; which creates a strong advocate for Welsh speakers and will improve the quality and quantity of services available through the medium of Welsh. I believe that everyone who wants to access services in the Welsh language should be able to do so, and that is what this government has worked towards. This legislation is an important and historic step forward for
5929-611: The Birmingham Corporation Water Act in 1892. It allowed the corporation to acquire by compulsory purchase all the land within the water catchment area of the Elan Valleys . Thousands of navvies (workers) and their families lived in the purpose-built Elan Village during the construction of the first four dams at the turn of the 20th century. In 1952, the Claerwen dam was opened by Elizabeth II in one of her first official engagements as monarch. Drinking water from
6050-575: The Dol-y-mynach, Ciloerwynt and Pant-y-beddau dams were dropped because of improvements in civil engineering and materials. Instead, work began on a single, much larger, concrete dam higher up the valley. As its designers wanted the Claerwen dam to visually match the earlier dams in the Elan Valley, Italian stonemasons were contracted to decorate the facade in a mock Victorian ashlar . Queen Elizabeth II officially opened Claerwen Reservoir in 1952 in one of her first engagements as monarch. A scale model of
6171-565: The Elan River and the Aberdeuddwr quarry on Cerrig Gwynion, just to the south of Rhayader. The shaped stones were hauled by locomotive to the dam sites on flatbed trucks. They were then lowered into place by steam crane . The central cores of the dams were encased with a 2-metre (6 ft 7 in) concrete lining. The outside walls were faced with cut stone brought from quarries at Llanelwedd near Builth Wells and Pontypridd . The cement, which
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#17330851493686292-476: The Elan Valley from a junction near Rhayader on the Mid-Wales Railway . The first section to be built was a 4-kilometre (2.5 mi) branch from the main line at Rhayader to the main work site at the Caban-coch dam. This depot included a cement cooling shed, general stores, coal storage, workshops for carpenters, smiths, fitters and wagon builders, and sawmills. Further branches were eventually built to all
6413-558: The Elan Valley is noted for being exceptionally soft , contrasting with water from local supplies in the West Midlands, not served by the Elan aqueduct, which are noted for hardness . The reservoirs are now owned and managed by Dŵr Cymru Welsh Water . The water filtration works further down the valley is run by Severn Trent Water . There are four main dams and reservoirs (constructed 1893–1904 in Elan Valley, and 1946–1952 at Claerwen) with
6534-539: The Greater London area. The Welsh Language Board , on the basis of an analysis of the Office for National Statistics Longitudinal Study, estimated there were 110,000 Welsh-speaking people in England, and another thousand in Scotland and Northern Ireland. In the 2011 census , 8,248 people in England gave Welsh in answer to the question "What is your main language?" The Office for National Statistics subsequently published
6655-710: 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
6776-485: 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
6897-489: The Welsh Language (Wales) Measure 2011, all new signs have Welsh displayed first. There have been incidents of one of the languages being vandalised, which may be considered a hate crime . Since 2000, the teaching of Welsh has been compulsory in all schools in Wales up to age 16; this has had an effect in stabilising and reversing the decline in the language. Text on UK coins tends to be in English and Latin. However,
7018-436: The Welsh Language Scheme. The list of other public bodies which have to prepare Schemes could be added to by initially the Secretary of State for Wales, from 1993 to 1997, by way of statutory instrument . Subsequent to the forming of the National Assembly for Wales in 1997, the Government Minister responsible for the Welsh language can and has passed statutory instruments naming public bodies who have to prepare Schemes. Neither
7139-421: The Welsh language official status in Wales. Welsh and English are de jure official languages of the Welsh Parliament, the Senedd , with Welsh being the only de jure official language in any part of the United Kingdom, with English being merely de facto official. According to the 2021 census , the Welsh-speaking population of Wales aged three or older was 538,300 (17.8%) and nearly three quarters of
7260-445: The Welsh language, though some had concerns over her appointment: Plaid Cymru spokeswoman Bethan Jenkins said, "I have concerns about the transition from Meri Huws's role from the Welsh Language Board to the language commissioner, and I will be asking the Welsh government how this will be successfully managed. We must be sure that there is no conflict of interest, and that the Welsh Language Commissioner can demonstrate how she will offer
7381-426: The Welsh of the 16th century, but they are similar enough for a fluent Welsh speaker to have little trouble understanding it. During the Modern Welsh period, there has been a decline in the popularity of the Welsh language: the number of Welsh speakers declined to the point at which there was concern that the language would become extinct. During industrialisation in the late 19th century, immigrants from England led to
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#17330851493687502-429: The Welsh-speaking heartlands, with the number dropping to under 50 per cent in Ceredigion and Carmarthenshire for the first time. However, according to the Welsh Language Use Survey in 2019–20, 22 per cent of people aged three and over were able to speak Welsh. The Annual Population Survey (APS) by the Office for National Statistics (ONS) estimated that as of March 2024, approximately 862,700, or 28.0 per cent of
7623-413: 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
7744-428: 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:
7865-450: 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
7986-408: The census. In terms of usage, ONS also reported that 14.4 per cent (443,800) of people aged three or older in Wales reported that they spoke Welsh daily in March 2024, with 5.4 per cent (165,500) speaking it weekly and 6.5 per cent (201,200) less often. Approximately 1.7 per cent (51,700) reported that they never spoke Welsh despite being able to speak the language, with the remaining 72.0 per cent of
8107-455: The construction village was powered by hydroelectric generators . A century later, small-scale hydro-generation was again introduced as a by-product of some of the Elan Valley reservoirs. As of 2013, a renewable-energy firm, Infinis, is operating five water turbines in the district with a combined capacity of about 4 MW . The project to supply water to Birmingham was officially opened by King Edward VII and Queen Alexandra on 21 July 1904. As
8228-442: 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
8349-414: The course of the 20th century this monolingual population all but disappeared, but a small percentage remained at the time of the 1981 census. Most Welsh-speaking people in Wales also speak English. However, many Welsh-speaking people are more comfortable expressing themselves in Welsh than in English. A speaker's choice of language can vary according to the subject domain and the social context, even within
8470-489: The creation of Old Welsh, Davies suggests it may be more appropriate to refer to this derivative language as Lingua Britannica rather than characterising it as a new language altogether. The argued dates for the period of "Primitive Welsh" are widely debated, with some historians' suggestions differing by hundreds of years. The next main period is Old Welsh ( Hen Gymraeg , 9th to 11th centuries); poetry from both Wales and Scotland has been preserved in this form of
8591-404: 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 ),
8712-470: The decline in Welsh speakers particularly in the South Wales Valleys. Welsh government processes and legislation have worked to increase the proliferation of the Welsh language, for example through education. Welsh has been spoken continuously in Wales throughout history; however, by 1911, it had become a minority language, spoken by 43.5 per cent of the population. While this decline continued over
8833-460: 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
8954-507: 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
9075-440: 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
9196-491: 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
9317-471: The first four dams provided enough drinking water to meet Birmingham's needs in the early 20th century, it was proposed not to proceed with the damming of the River Claerwen at Dol-y-mynach, Ciloerwynt and Pant-y-beddau until the 1930s. However, that phase of construction was postponed due to the outbreak of the Second World War . It was not until 1946 that work began on damming the Claerwen. Plans to build
9438-413: 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
9559-485: The following decades, the language did not die out. The smallest number of speakers was recorded in 1981 with 503,000 although the lowest percentage was recorded in the most recent census in 2021 at 17.8 per cent. By the start of the 21st century, numbers began to increase once more, at least partly as a result of the increase in Welsh-medium education . The 2004 Welsh Language Use Survey showed that 21.7 per cent of
9680-463: The highest number of native speakers who use the language on a daily basis, and it is the Celtic language which is considered the least endangered by UNESCO . The Welsh Language Act 1993 and the Government of Wales Act 1998 provide that the Welsh and English languages be treated equally in the public sector, as far as is reasonable and practicable. Each public body is required to prepare for approval
9801-413: The highest percentage of residents giving Welsh as their main language. The census also revealed that 3,528 wards in England, or 46% of the total number, contained at least one resident whose main language is Welsh. In terms of the regions of England , North West England (1,945), London (1,310) and the West Midlands (1,265) had the highest number of people noting Welsh as their main language. According to
9922-451: The history of Welsh, with rather indistinct boundaries: Primitive Welsh, Old Welsh, Middle Welsh, and Modern Welsh. The period immediately following the language's emergence is sometimes referred to as Primitive Welsh, followed by the Old Welsh period – which is generally considered to stretch from the beginning of the 9th century to sometime during the 12th century. The Middle Welsh period
10043-580: 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
10164-494: The lack of clean water. Victorian politician Joseph Chamberlain , the leader of Birmingham City Council , began a campaign to get clean water from the Elan and Claerwen valleys in mid Wales. The area, which had been identified by civil engineer James Mansergh , would be ideal for water reservoirs because: In 1892, Parliament passed the Birmingham Corporation Water Act allowing the Corporation to effect compulsory purchase of
10285-432: 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
10406-587: The language already dropping inflections in the declension of nouns. Janet Davies proposed that the origins of the Welsh language were much less definite; in The Welsh Language: A History , she proposes that Welsh may have been around even earlier than 600 AD. This is evidenced by the dropping of final syllables from Brittonic: * bardos 'poet' became bardd , and * abona 'river' became afon . Though both Davies and Jackson cite minor changes in syllable structure and sounds as evidence for
10527-496: The language, its speakers and for the nation." The measure was not welcomed warmly by all supporters: Bethan Williams, chairman of the Welsh Language Society, gave a mixed response to the move, saying, "Through this measure we have won official status for the language and that has been warmly welcomed. But there was a core principle missing in the law passed by the Assembly before Christmas. It doesn't give language rights to
10648-546: The language. As Germanic and Gaelic colonisation of Britain proceeded, the Brittonic speakers in Wales were split off from those in northern England, speaking Cumbric, and those in the southwest, speaking what would become Cornish , so the languages diverged. Both the works of Aneirin ( Canu Aneirin , c. 600 ) and the Book of Taliesin ( Canu Taliesin ) were written during this era. Middle Welsh ( Cymraeg Canol )
10769-455: The middle of the 11-metre (36 ft) dam wall was caused by a charge placed at its base. The lessons learned at Nant-y-Gro green lit the development of the "Upkeep" bouncing bombs . They were used in the 1943 Dam Busters raid when RAF Bomber Command breached and damaged several dams in the Ruhr Valley , Germany. The remains of the breached Nant-y-Gro dam are in much the same state as it
10890-610: The modern period across the border in England. Archenfield was still Welsh enough in the time of Elizabeth I for the Bishop of Hereford to be made responsible, together with the four Welsh bishops, for the translation of the Bible and the Book of Common Prayer into Welsh. Welsh was still commonly spoken there in the first half of the 19th century, and churchwardens' notices were put up in both Welsh and English until about 1860. Alexander John Ellis in
11011-470: 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
11132-423: The navvies lived in a village of wooden huts near the site. This settlement, which was strictly controlled to keep order and health, would eventually become Elan Village (see Elan Valley ). Guards controlled access in and out; this was done to reduce illness and to stop liquor smuggling. All new workers were deloused and examined for infectious diseases before being admitted. To keep order, a man and his wife shared
11253-542: 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
11374-448: The number of Welsh-language speakers to one million by 2050. Since 1980, the number of children attending Welsh-medium schools has increased, while the number going to Welsh bilingual and dual-medium schools has decreased. Welsh is considered the least endangered Celtic language by UNESCO . The language of the Welsh developed from the language of Britons . The emergence of Welsh was not instantaneous and clearly identifiable. Instead,
11495-415: 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
11616-428: 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
11737-418: The other dam sites. Engines and trucks reached the top of the dams on wooden trestle scaffolds supported by concrete parapets. The line went as far as the site where the foundations of the Dol-y-mynach dam were being built (lower down the valley from the later Claerwen dam). At its height, the railway had a total length of 45 kilometres (28 mi) with six locomotives transporting up to 1,000 tons of materials
11858-464: The people of Wales in every aspect of their lives. Despite that, an amendment to that effect was supported by 18 Assembly Members from three different parties, and that was a significant step forward." On 5 October 2011, Meri Huws , Chair of the Welsh Language Board , was appointed the new Welsh Language Commissioner. She released a statement that she was "delighted" to have been appointed to
11979-534: The people of the Western Roman Empire . In Old English the term went through semantic narrowing , coming to refer to either Britons in particular or, in some contexts, slaves. The plural form Wēalas evolved into the name for their territory, Wales. The modern names for various Romance-speaking people in Continental Europe (e.g. Walloons , Valaisans , Vlachs / Wallachians , and Włosi ,
12100-484: The population in Wales said they had no Welsh language skills. Other estimates suggest that 862,700 people (28.0%) aged three or older in Wales could speak Welsh in March 2024. Almost half of all Welsh speakers consider themselves fluent, while 20 per cent are able to speak a fair amount. 56 per cent of Welsh speakers speak the language daily, and 19 per cent speak the language weekly. The Welsh Government plans to increase
12221-471: The population not being able to speak it. The National Survey for Wales, conducted by Welsh Government, has also tended to report a higher percentage of Welsh speakers than the census, with the most recent results for 2022–2023 suggesting that 18 per cent of the population aged 3 and over were able to speak Welsh, with an additional 16 per cent noting that they had some Welsh-speaking ability. Historically, large numbers of Welsh people spoke only Welsh. Over
12342-502: The population of Wales aged 3 and over, were able to speak the language. Children and young people aged three to 15 years old were more likely to report that they could speak Welsh than any other age group (48.4 per cent, 241,300). Around 1,001,500 people, or 32.5 per cent, reported that they could understand spoken Welsh. 24.7 per cent (759,200) could read and 22.2 per cent (684,500) could write in Welsh. The APS estimates of Welsh language ability are historically higher than those produced by
12463-407: The population of Wales spoke Welsh, compared with 20.8 per cent in the 2001 census , and 18.5 per cent in the 1991 census . Since 2001, however, the number of Welsh speakers has declined in both the 2011 and 2021 censuses to about 538,300 or 17.8 per cent in 2021, lower than 1991, although it is still higher in absolute terms. The 2011 census also showed a "big drop" in the number of speakers in
12584-428: 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
12705-437: 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,
12826-464: 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,
12947-527: The required fresh approach to this new role." Huws started her role as the Welsh Language Commissioner on 1 April 2012. Local councils and the Senedd use Welsh, issuing Welsh versions of their literature, to varying degrees. Road signs in Wales are in Welsh and English. Prior to 2016, the choice of which language to display first was the responsibility of the local council. Since then, as part of
13068-522: The reservoir network, in the form of ornamental ponds, is located in Cannon Hill Park in Birmingham. In 1942, the Nant-y-Gro dam, which had been originally built to provide water for the navvies' village, was used by Barnes Wallis to prove his theory that an underwater explosion could create sufficient hydrostatic pressure to collapse a dam wall. The test proved successful as a significant breach in
13189-627: 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
13310-627: The shift occurred over a long period, with some historians claiming that it had happened by as late as the 9th century , with a watershed moment being that proposed by linguist Kenneth H. Jackson , the Battle of Dyrham , a military battle between the West Saxons and the Britons in 577 AD, which split the South Western British from direct overland contact with the Welsh. Four periods are identified in
13431-465: The total water catchment area of the Elan and Claerwen valleys (approximately 180 square kilometres (69 sq mi). The Act also gave Birmingham Corporation powers to move more than 100 people living in the Elan Valley. All the buildings were demolished; these included three manor houses (two of which had links with the English Romantic poet Percy Bysshe Shelley in 1812), 18 farms, a school and
13552-518: The use of Welsh in daily life, and standardised spelling. The New Testament was translated by William Salesbury in 1567, and the complete Bible by William Morgan in 1588. Modern Welsh is subdivided into Early Modern Welsh and Late Modern Welsh. Early Modern Welsh ran from the 15th century through to the end of the 16th century, and the Late Modern Welsh period roughly dates from the 16th century onwards. Contemporary Welsh differs greatly from
13673-493: 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
13794-412: 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
13915-476: 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
14036-608: Was complete by around AD 550, and labelled the period between then and about AD 800 "Primitive Welsh". This Primitive Welsh may have been spoken in both Wales and the Hen Ogledd ('Old North') – the Brittonic-speaking areas of what are now northern England and southern Scotland – and therefore may have been the ancestor of Cumbric as well as Welsh. Jackson, however, believed that the two varieties were already distinct by that time. The earliest Welsh poetry – that attributed to
14157-563: Was left in 1942, although partly obscured by trees. After the Dam Busters raid, steel cables were strung across the valley above the Caban-coch reservoir as a precautionary measure against German reprisals. In the early 1970s, it was proposed that the Craig-goch reservoir should be substantially increased in size with a new and higher downstream dam together with another dam to the north-west, impounding water that would otherwise have flowed down
14278-466: Was made near Chatham in Kent , was sent by sea to Aberystwyth and brought by railway to the Elan Valley. The cost of the Elan valley scheme ran over budget because of the failure to find suitable building stone near any of the dams apart from Caban-coch, as well as the necessity of bringing in facing stone from other quarries in mid and south Wales. During the ten-year project to build the Elan Valley dams,
14399-518: Was passed and received Royal Assent, thus making the Welsh language an officially recognised language within Wales. The measure: The measure required public bodies and some private companies to provide services in Welsh. The Welsh government's Minister for Heritage at the time, Alun Ffred Jones , said, "The Welsh language is a source of great pride for the people of Wales, whether they speak it or not, and I am delighted that this measure has now become law. I am very proud to have steered legislation through
14520-505: Was probably spoken throughout the island south of the Firth of Forth . During the Early Middle Ages the British language began to fragment due to increased dialect differentiation, thus evolving into Welsh and the other Brittonic languages. It is not clear when Welsh became distinct. Linguist Kenneth H. Jackson has suggested that the evolution in syllabic structure and sound pattern
14641-482: Was started in 1896 and opened in 1906, crosses several valleys and features numerous brick tunnels, pipelines, and valve houses. Work to build the Elan Valley reservoirs was undertaken because the rapid growth of the industrial city of Birmingham in the late 19th century had led to a lack of available clean water. Numerous outbreaks of disease prompted Birmingham City Council to petition the British government which passed
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