|
Lake Vyrnwy ((ウェールズ語:Llyn Efyrnwy), or ') is a reservoir in Powys, Wales. Its stone-built dam, built in the 1880s, was the first of its kind in the world. It was built for the purpose of supplying Liverpool and the districts later designated as Merseyside with fresh water. It flooded the head of the Vyrnwy valley and submerged the small village of Llanwddyn. The ''Lake Vyrnwy Nature Reserve and Estate'' that surrounds the lake is jointly managed by the Royal Society for the Protection of Birds (RSPB) and Severn Trent Water, and is a popular destination for days out, and for ornithologists, cyclists and hikers. The reserve is designated as a national nature reserve, a Site of Special Scientific Interest, a Special Protection Area, and a Special Area of Conservation. ==The dam== Dr George Deacon (1843–1909) began the design of the Vyrnwy Dam in 1879 at the age of 36. In 1890, following Vyrnwy, he founded an engineering practice in London which subsequently became Sir Alexander Binnie Son & Deacon, then Mr Binnie and Partners. Its present-day successor is Black & Veatch. Dr Deacon was instructed to prepare the parliamentary plans for the scheme in 1879. The dam construction started in 1881 and was completed in 1888. It was the first large stone-built dam in the United Kingdom, and is built partly out of great blocks of Welsh slate. When built it cost £620,000, . The dam is high from the bottom of the valley, and thick at the base; it is long and has a road bridge running along the top. It is decorated with over 25 arches and two small towers (each with four corner turrets) rising above the road surface. Vyrnwy was the first dam to carry water over its crest instead of in a channel at the side. At the bottom of the dam is a body of water known as a Stilling Basin, this is necessary to absorb the energy when the water flows over the crest and into the valley, and to stop the water eroding the foundations of the dam. A power house located under the west tower contains an electrical generator driven by water leaving the reservoir. Before mains electricity arrived in the 1960s this was the area's only source of power. The west and east Towers release compensation water by huge valves, which are controlled by Severn Trent Water. This water flows into for the River Vyrnwy, which would otherwise dry out unless in flood. Depending on the water levels downstream the reservoir can release anything from of compensation water per day. This flow is measured by the Environment Agency at a weir few hundred metres downstream. Earlier dams in Britain had been built using great earth embankments to hold back the water. This new type of stone dam would change the face of the Welsh landscape over the coming years. The next stone dams to be built in Wales on an even bigger scale than Vyrnwy were those built in the Elan Valley. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lake Vyrnwy」の詳細全文を読む スポンサード リンク
|