124-626: Rhayader ( / ˈ r eɪ . ə d ər / ; Welsh : Rhaeadr Gwy ; pronounced [ˈr̥əɪadar ˈɡʊi̯] ) is a market town and community in Powys , Wales, within the historic county of Radnorshire . The town is 20 miles (32 km) from the source of the River Wye on Plynlimon , the highest point of the Cambrian Mountains , and is located at the junction of the A470 road and
248-414: A Commission of Inquiry being set up, and most of Rebecca's grievances were righted two years later. In the 1890s the rapidly expanding city of Birmingham , 80 miles (130 kilometres) east, viewed the nearby Elan Valley as the ideal source of clean, safe water. This was to change the face of Rhayader forever, bringing thousands of workers involved in building this massive complex of dams and reservoirs to
372-441: 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
496-594: 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
620-401: A balancing compression stress in the downstream face, providing additional economy. For this type of dam, it is essential to have an impervious foundation with high bearing strength. Permeable foundations have a greater likelihood of generating uplift pressures under the dam. Uplift pressures are hydrostatic pressures caused by the water pressure of the reservoir pushing up against the bottom of
744-663: 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
868-544: A dam as "jurisdictional" or "non-jurisdictional" varies by location. In the United States, each state defines what constitutes a non-jurisdictional dam. In the state of Colorado a non-jurisdictional dam is defined as a dam creating a reservoir with a capacity of 100 acre-feet or less and a surface area of 20 acres or less and with a height measured as defined in Rules 4.2.5.1. and 4.2.19 of 10 feet or less. In contrast,
992-499: A dam that directed waterflow. It was finished in 251 BC. A large earthen dam, made by Sunshu Ao , the prime minister of Chu (state) , flooded a valley in modern-day northern Anhui Province that created an enormous irrigation reservoir (100 km (62 mi) in circumference), a reservoir that is still present today. Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on
1116-493: A distinct vertical curvature to it as well lending it the vague appearance of a concave lens as viewed from downstream. The multiple-arch dam consists of a number of single-arch dams with concrete buttresses as the supporting abutments, as for example the Daniel-Johnson Dam , Québec, Canada. The multiple-arch dam does not require as many buttresses as the hollow gravity type but requires a good rock foundation because
1240-519: A dystopian version of Rhayader called East Carmine. The name, Rhayader , is a partly-Anglicised form of its Welsh name, Y Rhaeadr ('the waterfall'), or, to distinguish it from other places named after waterfalls, Rhaeadr Gwy ('waterfall [on the] Wye'). Strictly speaking, according to place-name spelling conventions in Welsh, the name of the town would be Rhaeadr-gwy , and the waterfall itself Rhaeadr Gwy , but it seems that this distinction
1364-478: A grand scale." Roman planners introduced the then-novel concept of large reservoir dams which could secure a permanent water supply for urban settlements over the dry season. Their pioneering use of water-proof hydraulic mortar and particularly Roman concrete allowed for much larger dam structures than previously built, such as the Lake Homs Dam , possibly the largest water barrier to that date, and
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#17328022084241488-511: A minor tributary of the Nieuwe Maas . The central square of Amsterdam, covering the original site of the 800-year-old dam, still carries the name Dam Square . The Romans were the first to build arch dams , where the reaction forces from the abutment stabilizes the structure from the external hydrostatic pressure , but it was only in the 19th century that the engineering skills and construction materials available were capable of building
1612-509: A notable increase in interest in SHPs. Couto and Olden (2018) conducted a global study and found 82,891 small hydropower plants (SHPs) operating or under construction. Technical definitions of SHPs, such as their maximum generation capacity, dam height, reservoir area, etc., vary by country. A dam is non-jurisdictional when its size (usually "small") excludes it from being subject to certain legal regulations. The technical criteria for categorising
1736-643: A number of World Championship events in lesser celebrated sports, including wheelbarrow racing and rock-paper-scissors . Rhayader and its surrounding districts are supported by development organisation Rhayader 2000 Ltd, established in 1996 to revive Rhayader's economy. Rhayader 2000 Ltd is a voluntary sector organisation representing a cross section of the local community. It builds links with Powys County Council , Rhayader Town Council, local businesses and charitable and voluntary organisations. Welsh language Welsh ( Cymraeg [kəmˈraːiɡ] or y Gymraeg [ə ɡəmˈraːiɡ] )
1860-649: A profession based on a rigorously applied scientific theoretical framework. This new emphasis was centered around the engineering faculties of universities in France and in the United Kingdom. William John Macquorn Rankine at the University of Glasgow pioneered the theoretical understanding of dam structures in his 1857 paper On the Stability of Loose Earth . Rankine theory provided a good understanding of
1984-566: A settling pond, and a 1,000 m (3,300 ft) canal to a distribution tank. These works were not finished until 325 AD when the dam permitted the irrigation of 25,000 acres (100 km ). Eflatun Pınar is a Hittite dam and spring temple near Konya , Turkey. It is thought to date from the Hittite empire between the 15th and 13th centuries BC. The Kallanai is constructed of unhewn stone, over 300 m (980 ft) long, 4.5 m (15 ft) high and 20 m (66 ft) wide, across
2108-479: 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
2232-408: A whole dam itself, that dam also would be held in place by gravity, i.e., there is no tension in the upstream face of the dam holding the top of the dam down. The designer does this because it is usually more practical to make a dam of material essentially just piled up than to make the material stick together against vertical tension. The shape that prevents tension in the upstream face also eliminates
2356-926: 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
2480-474: Is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation , human consumption , industrial use , aquaculture , and navigability . Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve
2604-540: 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. Dam A dam
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#17328022084242728-635: 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
2852-424: Is dependent on the strength of the side wall abutments, hence not only should the arch be well seated on the side walls but also the character of the rock should be carefully inspected. Two types of single-arch dams are in use, namely the constant-angle and the constant-radius dam. The constant-radius type employs the same face radius at all elevations of the dam, which means that as the channel grows narrower towards
2976-471: Is sloped the distribution is more complicated. The normal component of the weight of the arch ring may be taken by the arch action, while the normal hydrostatic pressure will be distributed as described above. For this type of dam, firm reliable supports at the abutments (either buttress or canyon side wall) are more important. The most desirable place for an arch dam is a narrow canyon with steep side walls composed of sound rock. The safety of an arch dam
3100-511: 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
3224-399: Is the more widely used of the two, though the hollow dam is frequently more economical to construct. Grand Coulee Dam is a solid gravity dam and Braddock Locks & Dam is a hollow gravity dam. A gravity dam can be combined with an arch dam into an arch-gravity dam for areas with massive amounts of water flow but less material available for a pure gravity dam. The inward compression of
3348-590: Is the thinnest arch dam in the world and one of the oldest arch dams in Asia. It was constructed some 700 years ago in Tabas county , South Khorasan Province , Iran . It stands 60 meters tall, and in crest is a one meter width. Some historians believe the dam was built by Shāh Abbās I, whereas others believe that he repaired it. In the Netherlands , a low-lying country, dams were often built to block rivers to regulate
3472-512: Is usually ignored. In the Welsh of the area the name is Rheiad , as one would expect on the pattern of similar words in colloquial Welsh, pronounced [ˈr̥əɪad] . That is, a final "r" is dropped after "d", as in aradr ('plough') > arad , Llangynidr ('church of Cynidr', a village in Breconshire) > Llangynid , Cadwaladr (a forename, 'battle-leader') > Cadwalad , 'Dwalad . Little remains of
3596-732: 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
3720-500: 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
3844-466: 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
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3968-730: The A44 road 13 miles (21 km) north of Builth Wells and 30 miles (48 km) east of Aberystwyth . The population was 2,088, with 55% of the community having some form of Welsh identity, according to the 2011 census. The community is the largest in Wales by area, with 137.31 km (53.02 sq mi). It includes the Elan Valley . Rhayader holds the record for the lowest-ever temperature recorded in Wales , -23.3 °C on 21 January 1940. Jasper Fforde’s novels “Red Side Story” and “Shades of Grey: The Road to High Saffron” are located in
4092-538: 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
4216-657: The Fayum Depression to the Nile in Middle Egypt. Two dams called Ha-Uar running east–west were built to retain water during the annual flood and then release it to surrounding lands. The lake called Mer-wer or Lake Moeris covered 1,700 km (660 sq mi) and is known today as Birket Qarun. By the mid-late third millennium BC, an intricate water-management system in Dholavira in modern-day India
4340-579: The Harbaqa Dam , both in Roman Syria . The highest Roman dam was the Subiaco Dam near Rome ; its record height of 50 m (160 ft) remained unsurpassed until its accidental destruction in 1305. Roman engineers made routine use of ancient standard designs like embankment dams and masonry gravity dams. Apart from that, they displayed a high degree of inventiveness, introducing most of
4464-597: The League of Wales - the top-tier of domestic Welsh football between 1997 and 2002, ceased to exist in the summer of 2006. The club has since reformed, and in its inaugural season gained promotion into the Spar Mid Wales League . A subsequent promotion to the Cymru Alliance followed, but a finishing position of 15th saw the team relegated after just one season. The town's rugby union team play in
4588-756: 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
4712-640: 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
4836-645: The University of Oxford published a study of the cost of large dams – based on the largest existing dataset – documenting significant cost overruns for a majority of dams and questioning whether benefits typically offset costs for such dams. Dams can be formed by human agency, natural causes, or even by the intervention of wildlife such as beavers . Man-made dams are typically classified according to their size (height), intended purpose or structure. Based on structure and material used, dams are classified as easily created without materials, arch-gravity dams , embankment dams or masonry dams , with several subtypes. In
4960-490: The waterfall itself, it having been destroyed in 1780 to make way for the bridge linking the town to Cwmdauddwr and the Elan Valley , the Lakeland of Wales. Rhayader has long been a natural stopping point for travellers – the Romans had a stop-over camp in the Elan Valley , monks travelled between the abbeys of Strata Florida and Abbeycwmhir and drovers headed to the lucrative markets with their livestock. It
5084-542: 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
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5208-564: The 15th and 13th centuries BC. The Kallanai Dam in South India, built in the 2nd century AD, is one of the oldest water regulating structures still in use. Roman engineers built dams with advanced techniques and materials, such as hydraulic mortar and Roman concrete, which allowed for larger structures. They introduced reservoir dams, arch-gravity dams, arch dams, buttress dams, and multiple arch buttress dams. In Iran, bridge dams were used for hydropower and water-raising mechanisms. During
5332-596: 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
5456-536: 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 ,
5580-675: The 1st–2nd centuries AD was found nearby in 1899. Known as the Rhayader Hoard, it is now in the Romano-British collection of the British Museum . Rhayader is an electoral ward to Powys County Council , electing one county councillor. As of 2022, the incumbent is Cllr Angela Davies of the Liberal Democrats . Rhayader Town Council represents the town at the local level, with 41 town councillors elected from
5704-486: 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
5828-489: The British began construction in 1898. The project was designed by Sir William Willcocks and involved several eminent engineers of the time, including Sir Benjamin Baker and Sir John Aird , whose firm, John Aird & Co. , was the main contractor. Capital and financing were furnished by Ernest Cassel . When initially constructed between 1899 and 1902, nothing of its scale had ever before been attempted; on completion, it
5952-530: The Cambrian Training Mid Wales League. There is also a cricket club and thriving local darts , dominos and pool leagues. The town is also well known by motocross fans. Every summer a series of events take place at the nearby Cwmythig Hill circuit, with many of Britain's top riders taking part. The race series regularly attracts over 5,000 spectators. As part of the annual carnival celebrations, Rhayader also plays host to
6076-520: The Colorado River is a constant-angle arch dam. A similar type is the double-curvature or thin-shell dam. Wildhorse Dam near Mountain City, Nevada , in the United States is an example of the type. This method of construction minimizes the amount of concrete necessary for construction but transmits large loads to the foundation and abutments. The appearance is similar to a single-arch dam but with
6200-680: The Colorado River. By 1997, there were an estimated 800,000 dams worldwide, with some 40,000 of them over 15 meters high. Early dam building took place in Mesopotamia and the Middle East . Dams were used to control water levels, for Mesopotamia's weather affected the Tigris and Euphrates Rivers. The earliest known dam is the Jawa Dam in Jordan , 100 kilometres (62 mi) northeast of
6324-550: 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
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#17328022084246448-714: The Middle Ages, dams were built in the Netherlands to regulate water levels and prevent sea intrusion. In the 19th century, large-scale arch dams were constructed around the British Empire, marking advances in dam engineering techniques. The era of large dams began with the construction of the Aswan Low Dam in Egypt in 1902. The Hoover Dam, a massive concrete arch-gravity dam, was built between 1931 and 1936 on
6572-610: The Middle East for water control. The earliest known dam is the Jawa Dam in Jordan , dating to 3,000 BC. Egyptians also built dams, such as Sadd-el-Kafara Dam for flood control. In modern-day India, Dholavira had an intricate water-management system with 16 reservoirs and dams. The Great Dam of Marib in Yemen, built between 1750 and 1700 BC, was an engineering wonder, and Eflatun Pinar, a Hittite dam and spring temple in Turkey, dates to
6696-639: The Rhayader and Cwmdauddwr community wards. The station on the Mid-Wales Railway line that served the town was closed on 31 December 1962. The nearest station is now 9 miles (14 kilometres) away, at Pen-y-Bont railway station, Crossgates on the Heart of Wales line , though connections are usually made at the more accessible Llandrindod railway station , a similar distance away. A bus service connects with outlying villages and neighbouring towns, with two-hourly daytime departures to Builth Wells , Llandrindod Wells , Aberystwyth and Newtown , with connections to Hereford , Shrewsbury and Cardiff . Due to
6820-437: The United States alone, there are approximately 2,000,000 or more "small" dams that are not included in the Army Corps of Engineers National Inventory of dams . Records of small dams are kept by state regulatory agencies and therefore information about small dams is dispersed and uneven in geographic coverage. Countries worldwide consider small hydropower plants (SHPs) important for their energy strategies, and there has been
6944-432: 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,
7068-436: 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
7192-421: 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
7316-445: 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
7440-426: 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
7564-429: 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
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#17328022084247688-457: The World Commission on Dams also includes in the "large" category, dams which are between 5 and 15 m (16 and 49 ft) high with a reservoir capacity of more than 3 million cubic metres (2,400 acre⋅ft ). Hydropower dams can be classified as either "high-head" (greater than 30 m in height) or "low-head" (less than 30 m in height). As of 2021 , ICOLD's World Register of Dams contains 58,700 large dam records. The tallest dam in
7812-403: The arch dam, stability is obtained by a combination of arch and gravity action. If the upstream face is vertical the entire weight of the dam must be carried to the foundation by gravity, while the distribution of the normal hydrostatic pressure between vertical cantilever and arch action will depend upon the stiffness of the dam in a vertical and horizontal direction. When the upstream face
7936-466: The area. A new railway was built connecting this huge area with the main network in Rhayader, and the construction of a new village to house the workers was built on the banks of the River Elan. Work started in 1894 and the scheme was officially opened in 1904 by King Edward VII and Queen Alexandra . The area around the town has several cairns and standing stones dating from several thousand years BCE. An important hoard of gold jewellery dating from
8060-497: The back of the dam through a large pipe to drive a water wheel and watermill . In the 10th century, Al-Muqaddasi described several dams in Persia. He reported that one in Ahwaz was more than 910 m (3,000 ft) long, and that it had many water-wheels raising the water into aqueducts through which it flowed into reservoirs of the city. Another one, the Band-i-Amir Dam, provided irrigation for 300 villages. Shāh Abbās Arch (Persian: طاق شاه عباس), also known as Kurit Dam ,
8184-438: The bottom of the dam the central angle subtended by the face of the dam becomes smaller. Jones Falls Dam , in Canada, is a constant radius dam. In a constant-angle dam, also known as a variable radius dam, this subtended angle is kept constant and the variation in distance between the abutments at various levels is taken care of by varying the radii. Constant-radius dams are much less common than constant-angle dams. Parker Dam on
8308-402: The buttress loads are heavy. In a gravity dam, the force that holds the dam in place against the push from the water is Earth's gravity pulling down on the mass of the dam. The water presses laterally (downstream) on the dam, tending to overturn the dam by rotating about its toe (a point at the bottom downstream side of the dam). The dam's weight counteracts that force, tending to rotate the dam
8432-450: The capital Amman . This gravity dam featured an originally 9-metre-high (30 ft) and 1 m-wide (3.3 ft) stone wall, supported by a 50 m-wide (160 ft) earthen rampart. The structure is dated to 3000 BC. However, the oldest continuously operational dam is Lake Homs Dam , built in Syria between 1319-1304 BC. The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, about 25 km (16 mi) south of Cairo ,
8556-408: 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
8680-422: The city. The masonry arch dam wall was designed by Lieutenant Percy Simpson who was influenced by the advances in dam engineering techniques made by the Royal Engineers in India . The dam cost £17,000 and was completed in 1856 as the first engineered dam built in Australia, and the second arch dam in the world built to mathematical specifications. The first such dam was opened two years earlier in France . It
8804-433: The construction of the Rideau Canal in Canada near modern-day Ottawa and built a series of curved masonry dams as part of the waterway system. In particular, the Jones Falls Dam , built by John Redpath , was completed in 1832 as the largest dam in North America and an engineering marvel. In order to keep the water in control during construction, two sluices , artificial channels for conducting water, were kept open in
8928-414: 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
9052-489: 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
9176-469: The dam by the water reduces the lateral (horizontal) force acting on the dam. Thus, the gravitational force required by the dam is lessened, i.e., the dam does not need to be so massive. This enables thinner dams and saves resources. A barrage dam is a special kind of dam that consists of a line of large gates that can be opened or closed to control the amount of water passing the dam. The gates are set between flanking piers which are responsible for supporting
9300-533: The dam was submitted by a consortium called Six Companies, Inc. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and the lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on 1 March 1936, more than two years ahead of schedule. By 1997, there were an estimated 800,000 dams worldwide, some 40,000 of them over 15 m (49 ft) high. In 2014, scholars from
9424-605: The dam. If large enough uplift pressures are generated there is a risk of destabilizing the concrete gravity dam. On a suitable site, a gravity dam can prove to be a better alternative to other types of dams. When built on a solid foundation, the gravity dam probably represents the best-developed example of dam building. Since the fear of flood is a strong motivator in many regions, gravity dams are built in some instances where an arch dam would have been more economical. Gravity dams are classified as "solid" or "hollow" and are generally made of either concrete or masonry. The solid form
9548-407: The dam. The first was near the base of the dam on its east side. A second sluice was put in on the west side of the dam, about 20 ft (6.1 m) above the base. To make the switch from the lower to upper sluice, the outlet of Sand Lake was blocked off. Hunts Creek near the city of Parramatta , Australia , was dammed in the 1850s, to cater to the demand for water from the growing population of
9672-450: The dams' potential range and magnitude of environmental disturbances. The International Commission on Large Dams (ICOLD) defines a "large dam" as "A dam with a height of 15 m (49 ft) or greater from lowest foundation to crest or a dam between 5 m (16 ft) metres and 15 metres impounding more than 3 million cubic metres (2,400 acre⋅ft )". "Major dams" are over 150 m (490 ft) in height. The Report of
9796-479: 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
9920-625: The first large-scale arch dams. Three pioneering arch dams were built around the British Empire in the early 19th century. Henry Russel of the Royal Engineers oversaw the construction of the Mir Alam dam in 1804 to supply water to the city of Hyderabad (it is still in use today). It had a height of 12 m (39 ft) and consisted of 21 arches of variable span. In the 1820s and 30s, Lieutenant-Colonel John By supervised
10044-742: The first was the Roman-built dam bridge in Dezful , which could raise water 50 cubits (c. 23 m) to supply the town. Also diversion dams were known. Milling dams were introduced which the Muslim engineers called the Pul-i-Bulaiti . The first was built at Shustar on the River Karun , Iran, and many of these were later built in other parts of the Islamic world . Water was conducted from
10168-491: 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
10292-534: The force of water. A fixed-crest dam is a concrete barrier across a river. Fixed-crest dams are designed to maintain depth in the channel for navigation. They pose risks to boaters who may travel over them, as they are hard to spot from the water and create induced currents that are difficult to escape. There is variability, both worldwide and within individual countries, such as in the United States, in how dams of different sizes are categorized. Dam size influences construction, repair, and removal costs and affects
10416-469: 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
10540-476: 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
10664-456: 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
10788-595: 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
10912-506: 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
11036-555: 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 )
11160-473: The large number of visitors that travel to the area all year round. Rhayader is also home to a community founded art and heritage complex which includes a museum and gallery, a leisure centre , numerous parks and all the amenities expected of a larger town. Potter Phil Rogers has his studio in Rhayader. There are an abundance of shops, cash facilities, restaurants, takeaways and supermarkets catering to both
11284-536: The local population and visitors to the area. Rhayader is also renowned for being the town with the highest concentration of pubs and drinking establishments, per capita , in the UK, with one to each 173 people. In nearby Nant-glas, across the river Wye from the village of Llanwrthwl , the Living Willow Theatre , an open-air theatre constructed of living willow trees, was opened in 2007. Rhayader Town F.C. , despite previously having some success in
11408-645: The main stream of the Kaveri River in Tamil Nadu , South India . The basic structure dates to the 2nd century AD and is considered one of the oldest water diversion or water regulating structures still in use. The purpose of the dam was to divert the waters of the Kaveri across the fertile delta region for irrigation via canals. Du Jiang Yan is the oldest surviving irrigation system in China that included
11532-622: 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
11656-456: The most important industries locally. Walkers and cyclists are drawn to Rhayader for the abundance of trails and bridleways surrounding the town, which is the gateway to a massive complex of reservoirs and dams (The Elan Valley ). This vast area is home to some of Britain's rarest wildlife and plants, including red kites , along with magnificent feats of engineering. There are a number of hotels, bed and breakfasts and campsites to accommodate
11780-448: 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,
11904-683: The other basic dam designs which had been unknown until then. These include arch-gravity dams , arch dams , buttress dams and multiple arch buttress dams , all of which were known and employed by the 2nd century AD (see List of Roman dams ). Roman workforces also were the first to build dam bridges, such as the Bridge of Valerian in Iran. In Iran , bridge dams such as the Band-e Kaisar were used to provide hydropower through water wheels , which often powered water-raising mechanisms. One of
12028-429: The other way about its toe. The designer ensures that the dam is heavy enough that the dam's weight wins that contest. In engineering terms, that is true whenever the resultant of the forces of gravity acting on the dam and water pressure on the dam acts in a line that passes upstream of the toe of the dam. The designer tries to shape the dam so if one were to consider the part of the dam above any particular height to be
12152-473: 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
12276-551: 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 ,
12400-488: 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
12524-471: 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
12648-502: 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
12772-407: 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
12896-469: The primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes ) are used to manage or prevent water flow into specific land regions. The word dam can be traced back to Middle English , and before that, from Middle Dutch , as seen in the names of many old cities, such as Amsterdam and Rotterdam . Ancient dams were built in Mesopotamia and
13020-607: The principles behind dam design. In France, J. Augustin Tortene de Sazilly explained the mechanics of vertically faced masonry gravity dams, and Zola's dam was the first to be built on the basis of these principles. The era of large dams was initiated with the construction of the Aswan Low Dam in Egypt in 1902, a gravity masonry buttress dam on the Nile River . Following their 1882 invasion and occupation of Egypt ,
13144-542: 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
13268-651: 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
13392-487: The state of New Mexico defines a jurisdictional dam as 25 feet or greater in height and storing more than 15 acre-feet or a dam that stores 50 acre-feet or greater and is six feet or more in height (section 72-5-32 NMSA), suggesting that dams that do not meet these requirements are non-jurisdictional. Most US dams, 2.41 million of a total of 2.5 million dams, are not under the jurisdiction of any public agency (i.e., they are non-jurisdictional), nor are they listed on
13516-639: The two inns in Rhayader at that date. Some changes were made in 1683, including the rebuilding of the three chimney stacks, and this date is carved into the old timbers inside the building. In the 19th century, turnpike roads were only passable on payment of extortionate tolls , imposing additional burdens on already poor communities. This led to the Rebecca Riots across South and Mid Wales from 1839 to 1842, with no fewer than six of Rhayader's tollgates being demolished with impunity by local farmers dressed as women. The actions of these "Rebeccaites" led to
13640-526: 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
13764-526: The volume of traffic generated by the convergence of two trunk roads — the A44 and the A470 — the construction of a bypass to relieve congestion at the town centre crossroads has been an ongoing debate for many years. The town is also a popular cycling centre and is on Route 8 of the United Kingdom National Cycle Network , known in Welsh as Lôn Las Cymru , 'Wales' green lane'. Tourism and agriculture are
13888-406: The water level and to prevent the sea from entering the marshlands. Such dams often marked the beginning of a town or city because it was easy to cross the river at such a place, and often influenced Dutch place names. The present Dutch capital, Amsterdam (old name Amstelredam ), started with a dam on the river Amstel in the late 12th century, and Rotterdam began with a dam on the river Rotte ,
14012-642: The water load, and are often used to control and stabilize water flow for irrigation systems. An example of this type of dam is the now-decommissioned Red Bluff Diversion Dam on the Sacramento River near Red Bluff, California . Barrages that are built at the mouths of rivers or lagoons to prevent tidal incursions or use the tidal flow for tidal power are known as tidal barrages . Embankment dams are made of compacted earth, and are of two main types: rock-fill and earth-fill. Like concrete gravity dams, embankment dams rely on their weight to hold back
14136-581: The world is the 305 m-high (1,001 ft) Jinping-I Dam in China . As with large dams, small dams have multiple uses, such as, but not limited to, hydropower production, flood protection, and water storage. Small dams can be particularly useful on farms to capture runoff for later use, for example, during the dry season. Small scale dams have the potential to generate benefits without displacing people as well, and small, decentralised hydroelectric dams can aid rural development in developing countries. In
14260-548: Was 102 m (335 ft) long at its base and 87 m (285 ft) wide. The structure was built around 2800 or 2600 BC as a diversion dam for flood control, but was destroyed by heavy rain during construction or shortly afterwards. During the Twelfth Dynasty in the 19th century BC, the Pharaohs Senosert III, Amenemhat III , and Amenemhat IV dug a canal 16 km (9.9 mi) long linking
14384-560: Was built. The system included 16 reservoirs, dams and various channels for collecting water and storing it. One of the engineering wonders of the ancient world was the Great Dam of Marib in Yemen . Initiated sometime between 1750 and 1700 BC, it was made of packed earth – triangular in cross-section, 580 m (1,900 ft) in length and originally 4 m (13 ft) high – running between two groups of rocks on either side, to which it
14508-622: 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
14632-488: Was linked by substantial stonework. Repairs were carried out during various periods, most importantly around 750 BC, and 250 years later the dam height was increased to 7 m (23 ft). After the end of the Kingdom of Saba , the dam fell under the control of the Ḥimyarites (c. 115 BC) who undertook further improvements, creating a structure 14 m (46 ft) high, with five spillways, two masonry-reinforced sluices,
14756-456: Was not until the 12th century that a documented history of the town began with the building of Rhayader Castle in 1177. Little remains today, with the exception of a dry moat that can be seen from Wauncapel Park. One of the oldest buildings in Rhayader is the Old Swan , which stands on the corner of West and South Streets Rhayader. The original building was mentioned in 1676 as being one of
14880-518: 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
15004-404: Was possibly the world's first concrete arch dam. Designed by Henry Charles Stanley in 1880 with an overflow spillway and a special water outlet, it was eventually heightened to 10 m (33 ft). In the latter half of the nineteenth century, significant advances in the scientific theory of masonry dam design were made. This transformed dam design from an art based on empirical methodology to
15128-517: 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
15252-461: Was the first French arch dam of the industrial era , and it was built by François Zola in the municipality of Aix-en-Provence to improve the supply of water after the 1832 cholera outbreak devastated the area. After royal approval was granted in 1844, the dam was constructed over the following decade. Its construction was carried out on the basis of the mathematical results of scientific stress analysis. The 75-miles dam near Warwick , Australia,
15376-682: Was the largest masonry dam in the world. The Hoover Dam is a massive concrete arch-gravity dam , constructed in the Black Canyon of the Colorado River , on the border between the US states of Arizona and Nevada between 1931 and 1936 during the Great Depression . In 1928, Congress authorized the project to build a dam that would control floods, provide irrigation water and produce hydroelectric power . The winning bid to build
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