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Hydropower

The hydroelectric power or hydropower is a renewable electrical energy obtained by scrabble word finder converting the hydraulic energy , the different flows of water 1 in electricity . The energy kinetics of water flow is converted into mechanical energy by a turbine and then into electrical energy by a generator . Hydroelectricity represents about 16% 2 of the world’s electricity and has many strengths. It is a renewable , low operating cost and has low greenhouse gas emissions. It has in some cases social and environmental drawbacks (see the case of dams located in non-mountainous regions: displacement, possibly flooding of agricultural land, changes in aquatic and terrestrial alluvial blocking …) Third source of power generation in Europe, hydroelectricity is made ​​to grow by integrating resource protection fish and articulating with other renewables such as wind or other hybrid systems (eg with hydrogen). Summary  [ hide ] 1 Principles 2 History 3 Power Projects 3.1 The central gravity 3.1.1 Classification by type of operation 3.1.2 Classification by type of fill 3.1.3 Ranking drop height 3.2 The STEP: Ski energy transfer pumping 3.3 The tidal power plants 3.3.1 From the tides 3.3.2 From the waves 3.3.3 From the ocean currents 4 Use the world 4.1 Brazil 4.2 China 03.04 U.S. 4.4 France 4.5 Iceland 4.6 Norway 4.7 Québec 4.8 Russia 04/09 Sweden 5 Cost of hydropower 6 Environment 7 Notes and references 8 Bibliography 9 See also 9.1 Related 9.2 notorious hydroelectric projects 9.3 External Links Principles

 

Cross section of a water turbine coupled to an electric generator. A Generator B Turbine A Stator 2 Rotor 3 Adjustable valves 4 Turbine blades 5 Water flow 6 Axis of rotation Related articles: turbine generator and hydraulic turbine . Electrical energy is produced by the transformation of the kinetic energy of water power through a hydraulic turbine coupled to an electric generator . For dams in the accumulation amount of energy available, over time, the reserve of water from a dam depends on its volume, inputs and natural losses over the period and the drop height . Dams for water over the amount of energy produced is directly related to flow (m³ / s, m³ / h m³ / day m³ / year). There are four types of turbines. The type of turbine most suitable is done by calculating the specific speed recorded ns . The Pelton turbine , suitable for high falls, with an overshot wheel, invented by Lester Allan Pelton in 1879. It is designed for drop height of over 200 meters The Francis turbine , instead of rising to falling mean or high, with an impeller single or double. Designed by James B. Francis in 1868. The Kaplan turbine was invented in 1912, ideally suited for low head and high flow rates, with a wheel-type helix , like a boat. Viktor Kaplan has developed a wheel propeller blades which can be guided by flow rates used. The Wells turbine , little known, uses the movement of air caused by the movement of waves through a vertical tube. Principle developed by Alan Wells. History

Human beings use the power of water for more than two thousand years. Indeed, they used water mills powered by water wheels to grind wheat.

Monumental entrance to the exhibition of 1925 Only in the XIX th century that the impellers are used to generate electricity. At the end of the century, the turbine will replace the water wheel and the first dam will emerge. In the Alps, the industrialist and engineer Aristide Berges uses the formula of “  white coal  “developed in Grenoble from 1878 in local meetings, and at the fair in Lyon in 1887, and finally popularized during the World Expo in Paris in 1889 , where Berg is the popular expression to characterize the hydraulic power in all its forms. In 1869, he used to Lancey water power to operate its shredders (grating devices in the wood to make paper pulp) with a drop of 200 meters. In 1925, Grenoble organizes the International Exhibition of water power in order to devote the capital city of white coal. Hydro

 

Sectional diagram of a hydroelectric dam. A – tank B – power plant, C – turbine, D – generator, E – valve F – penstock, G – power lines, H – River

Engine room of the hydroelectric Fessenheim . It recognizes the generators painted blue. There are three main forms of hydropower: the central gravitational say why the water supply in the reserve are only gravity the energy transfer stations by pumping (STEP) also hcg diet known as pumped storage hydro , for which an artificial device used to pump water from a lower reservoir to an upper reservoir. These include also frequently part gravity. the tidal power plants auto insurance rates in the broad sense that use the energy of motion of the sea, whether alternating tidal flow (tidal power in the strict sense), permanent ocean currents (tidal turbines in the strict sense) or wave motion. The central gravity  Main article: Small Hydropower . The central gravity are those taking advantage of the flow of water auctions online along a vertical drop to the ground. They can be classified into three types of operation, determining a different service for the electrical system. This ranking is based on the constant emptying, which is the theoretical time it would take to empty the reserve web hosting reviews turbines maximum power. Classification by type of operation  They include: plants say “over water” , the constant emptying is generally less than 2 hours; plants “hydropeaking” , whose constant dump is between 2 and 200 hours; the “lakes” (or reservoirs ), the constant drain of more than 200 hours. The run-of water , mainly located in lowland areas are reasons for these deductions of low height. They use the river’s flow as it stands, without significant capacity modulation storage. They provide an energy base 3 very inexpensive. They are typical of the vps hosting infrastructure development on major rivers like the Rhone and the Rhine. The central hydropeaking lakes are larger, allowing a modulation in the day or week. Their management can track the change in consumption of these time horizons (consumption peaks in the morning and evening, the difference between weekdays and weekend …). They are typical of the infrastructure development in the uplands. The central lake- match books with the most important reservoirs. These allow seasonal storage of water, and modulation of production to pass the peak load power consumption: the summer for countries where peak demand is determined by the air in the winter for those where it is determined by the heating. These plants are typical of the infrastructure development in middle and high mountains. Classification by type of electronic cigarette fill  It is also possible to classify plants according to the characteristics of filling their tanks, which leads to some constraints in using electricity that can be done. We distinguish, for example, vessels in which the filling can be obtained statistically on a weekly, seasonal, annual or multi-year, in the case of very large bodies of water such as Caniapiscau reservoir , created under the project of the Bay James , at Quebec 4 . Sort by height of fall  Main article: Height of fall . Finally, one can also classify the books according to their height of fall, that is to say the difference in elevation between the mirror theory of full tank and turbine. The drop height significantly determines the types of turbines used. They include: the high falls (> 200 m) the average falls (50 to 200 m) the low head (<50 m) Between these three types of classification, there is no strict equivalence but a strong correlation. Power over water are generally filled daily with regular inputs and low-head, filling the hydropeaking have daily or weekly influenced by the season (flood season) and drop heights average rarely high, and finally fills the lakes have generally seasonal (snow melt or rain season) and the heights of large drops. The STEP: Ski energy transfer pumping  Main article: pumped storage . These plants, in addition to producing energy from the natural flow, have a pumping how to store the energy produced by other types of plants when consumption is low, for example at night, for the redistribute in turbine mode, during peak consumption. These plants have two pools, a pool and a lower
basin than between which is placed a reversible hydro machine  : the hydraulic part can operate both pumps , that turbine and the electrical as well as motor in electronic cigarettes generator ( machine synchronous ). In accumulation mode the machine uses the current supplied to lift the water from the lower to the upper basin and in production mode the machine converts the gravitational potential energy of water into electricity. The efficiency (ratio between electricity consumption and electricity) is about 82%. This type of plant is of economic interest when the marginal costs of production vary significantly over a period of time (day, week, season, years …). They make it possible to store energy gravity, in periods when costs are low, they are available in periods when they are high.

Great Dixence  : the highest gravity dam in the world ( Alpiq , Switzerland ) This is for example the case if there are important recurrent variations in demand (between summer and winter, day or night …), productions “fatal” in large quantities, which would otherwise be lost ( wind ) or production of energy based low modulus (nuclear, hydro run of river). The STEP best locksmiths known in France is located in the valley of the Eau d’Olle (the Alps), and connects the lake Verney (selected downstream) to the dam Grand’Maison (adopted upstream). For cons, the oldest seems to be that of the Black Lake in the Vosges , Alsatian side, the name of the lake associated with the Lac Blanc . Conceived in the year 1930 , to regulate the production of the dam over water Kembs on the Rhine , its exploitation was the scene of a tragedy in which all staff perished with the exception of a survivor . She was placed in service after having equipped the penstock, a hundred meters in altitude, a surge against the hammer and located horizontally above the reconstructed building. In the Alps, a major project funded by France and supported by Europe, to build a hydroelectric plant known to produce 560 million kWh per year, equivalent to power a city of 280 000 residents will be completed in the coming years, the project “New Romanche” in the village of Livet-and-Gavet , south of Grenoble . The amount of the investment amounts to € 150 million, guaranteed for 80 to 90% by EDF. This is an underground powerhouse with two Francis turbines, built over the water, allowing better use of water power in the Romanche Valley . Leif-Erik Langhans, the Ruhr University of Bochum , also studied a system of wind coupled with a pumped storage casino hydroelectric plant. Wind energy surplus is used to bring water into a basin raised. In case of energy deficit, the supply of water passes through turbines that produce electricity. The tidal power plants  Main article: Tidal . A tidal power plant is a hydroelectric plant that uses the energy of the tides to generate electricity. From tides  The La Rance tidal power plant is an example of using tidal energy to generate electricity. From waves  Main article: Energy waves . The Japan focused on the resources of the first wave from 1945, followed by Norway and the United Kingdom . At the beginning of August 1995, the Ocean Swell Powered Renewable Energy (OSPREY), the first power plant using wave energy, is located north of Scotland . The principle is: the waves enter a kind of submerged caisson, open at the base, move air through the turbines that drive generators that generate electricity. This is then transmitted by submarine cable to the coast, distant about 300 meters. The plant had a power of 2 MW. Unfortunately, this book, damaged by the waves, was destroyed a month later by the tail of Hurricane Felix. Its creators are not discouraged. A new machine, cheaper and more efficient, is being developed. It should help provide power to small islands that lack it and to supply a desalination plant seawater From the ocean currents  Main article: turbine . A project of the British company Marine Current Turbines plans to use turbines (sort of “wind” underwater) that would use ocean currents similarly to a boat propeller to generate electricity. Use in the world

 

The Three Gorges Dam , in the province of Hubei in China , is the largest wedding ring dam and the largest generator of electricity in the world 5 . The water is the source of hydropower is storable and production of electricity can change rapidly, so it can be used in a point , that is to say, when demand is highest on the public network electrical distribution. However, hydropower production is limited by the speed and the available water supply, these reserves depend on the climate , the upstream pumping made ​​deductions (eg for the irrigation ) and the size of withholding (dams). Hydroelectric power installed worldwide in 2004 was estimated at 715 gigawatts (GW), about 19% of the global electric power. Nearly 15% of the installed capacity in Europe is from hydropower. However, the proportion of hydroelectric power generated is less than the installed capacity (around 16% 2 of the global electric power), but it plays a particularly important role to ensure a balanced snapshot of the production and electricity consumption, in fact, hydroelectric power is due to its flexibility (mobilized in minutes), a variable adjustment necessary because electrical energy can be stored very easily. China, Canada, Brazil and the United States are the largest producers of hydroelectricity. But instead of this renewable energy in national electricity production is highly variable and both countries stand out: Norway with 99% and Brazil with 84% 6 Brazil  The Brazilian is one of the largest global players in hydropower, accompanying China and Canada 7 . The Itaipu dam (in common with Paraguay ), and Belo Monte (under construction) are among the largest in the world. The Itaipu dam holds the world record of hydroelectric power produced in one year: 94.7 TWh in 2008 8 , ahead of the dam Chinese Three Gorges . Hydroelectric power accounts for about 90% of the electricity generated in Brazil 7 . China  China is one of the world’s largest producers of hydroelectric power and the largest producer of hydroelectric power stations 9 . The Three Gorges Dam is the largest dam in terms of hydro installed capacity (22.4 GW) 8 , and annual hydropower production reached 84.7 TWh. Other dams are located in the territory: the Ertan dam , the Banqiao Dam , the dam Ghezouba , the Longtan dam , the dam Zipingpu in Sichuan – a dam 156 meters high, completed in 2006, … United States [ change ] Hydroelectric production in the United States remains one of the largest in the world, with 317.7 TWh in 2006. Main article: United Énergie_aux_États # Hydro.C3.A9lectricit.C3.A9 . France  Main article: Energy in France . The first framework law hydroelectricity and the system of hydroelectric concessions date of the period of reconstruction that followed the First World War (Law of 16 October 1919 on the use of water power). Nearly a century later, in France , the installed capacity of 399 French dams is 25 GW, or 22% of all power plants contributing to the public networks while production is only about 15 %. In 2009, approximately 80% of these dams were operated by EDF . The Company’s hydroelectric Midi (Shem), which was acquired by the Belgian Electrabel ( Suez ) 10 , operates 50 dams and 12 hydroelectric plants in the Pyrenees. The CNR , public company with 49.97% stake is held by GDF SUEZ operates the dams along the river Rhone that he concedes the state.

Bridge-Dam St. Égrève in the suburbs of Grenoble In San Diego Homes For Rent July 2008, pursuant to an infringement procedure from the European Commission, the government decided 11 to compete in the allocation of hydroelectric concessions to their maturity 12 . For this, it brought together concessions for hydroelectric valleys. The first groups of concessions should be subject to competition before 2013 (dams in the valley of Ossau, dams Louron Valley Dam downstream to the river La Truyère , the upper and middle Dordogne and dams Drac ). At December 31, 2014, only the concession Bissorte Super Bissorte be renewed according to the above mentioned decree of September 26, 2008 in the valley of the Arc . Second form of production behind nuclear power, hydropower accounts for 12% of French electricity production and 95% of electricity generation from renewable sources. [ ref.  desired] In France, a hundred plants are associated with reservoirs created by dams, and over 2000 installations are installed “over water”. The distribution of these hydroelectric facilities throughout the territory and small power of each turbine allow for flexible electricity and close to places of consumption. The annual production is 67 TWh, which corresponds to the average annual consumption of 15 million people (a quarter of the French population). An installed capacity of 24,000 MW, 12,000 MW of peak power (mobilized in minutes and essential for the safety of the electrical system, (the installed capacity of 100 000 MW). France has just over 2000 plants with the flow, to 2000 MW installed, and 7 billion kWh produced an annual average. Iceland  Main article: Energy in Iceland . Norway [ change ] Main article: Energy in Norway . Quebec [ change ] Main articles: Energy in Quebec , Hydro-Québec and List of hydroelectric stations in Quebec . As is the case in Norway or Iceland, electricity in Quebec is essentially hydraulic source. weight loss pills In 2007, Quebec has a hydroelectric combined power of t shirt printing 37,459 MW , or 91% of the total 41,018 MW 13 . These plants annually produce 181.1 TWh (94% of total) 14 . The public company Hydro-Quebec has a virtual monopoly on the development of the sector. Small producers sell Plastic Storage Bins their production ( 1277 MW ) Hydro-Quebec under long-term commitment. The corporation also has almost all of the production of the Churchill Falls generating station in Labrador ( 5428 MW ) under a contract of 65 years which expires in 2041 Cell Phone Accessories 15 . After a reduction in the rate of investment in new production equipment instant payday loans in the 1990s, Hydro-Québec took over its construction program since 2002 with the commissioning of power plants of the Rock-de-Grand-Mere ( 230 megawatts ) in 2004; Toulnustouc in 2005 ( 526 megawatts ) Eastmain-1 in 2007 ( 480 MW ) 16  ; Péribonka ( 385 MW ) 17 and Mercier in 2008 ( 50.5 megawatts ) Rapides-des-Hearts ( 76 megawatts ) and Falls Allard ( 62 megawatts ) in 2009 18 . Two projects are still under construction. The first, Eastmain-1-A-Teal-Rupert is to build two power plants: 768 MW Eastmain-1-A – built 700 m from its neighbor opened in 2007 – and 150 megawatts in Teal and divert an annual average flow maximum of 452.6 m 3 / s (72%) of the Rupert River into the Eastmain-1 reservoir 19 . The derivation is completed in November 2009 and the six groups of both plants should all be put into operation by 2012. The total contribution of the energy project is estimated at 8.7 TWh per year 20 , including 5.3 TWh to power the Robert-Bourassa and La Grande-1 , the utilization factor of 57 increase 63% 21 . A second whole life insurance quotes project is built on the Romaine River on the North Shore. The Romaine project whose construction began in 2009 four power stations with a total capacity of 1550 MW Their estimated production will reach 8.0 TWh in their respective activations, between 2014 and 2020 22 . In its strategic plan published in 2009, Hydro-Québec also states that it will proceed with plans to increase power in SM-3 ( 440 MW ) and the central René-Lévesque ( 210 MW ) and Jean-Lesage ( 120 MW ) on River Manicouagan 23 . Russia  This section is empty, insufficiently detailed or incomplete. Your help is welcome! Category of hydroelectric dams in Russia Sweden  Main article: Energy in Sweden . Hydropower accounts for approximately half of the electricity produced in Sweden, the rest coming mainly from nuclear power. The hydropower development began in the 1880s, and has allowed the development of industry is very energy consuming, as the forest industry. The combined output of hydroelectric plants is 16,203 MW in 2009, mainly concentrated in high school seniors the north. The national company Vattenfall owns most of the plants. The major developments have taken place until the 1960s, the environmental protests that led to the protection of certain rivers. Cost of hydroelectricity

Despite generally high implementation costs, maintenance costs are reasonable, the facilities are expected to last a long time, and energy of the water is free and renewable if properly managed. So the picture is rather positive, it is a system of electricity production more profitable, it is also one of the most flexible. Environment

Hydropower is considered a clean and inexhaustible energy, unlike oil or natural gas . Some research 24 cast doubt on the results in greenhouse gas emissions from hydroelectric systems. The bacterial activity in water dams, especially in tropical regions, would release large amounts of methane (a gas with a greenhouse effect 20 times more potent than CO2). The environmental impacts vary with the type and size of the structure put in place: if they are weak to exploit the natural waterfalls, ocean currents, waves, but they become very large s’ it is about creating dams and artificial reservoirs. In the latter case, usually the critical loss of farmland and villages (leading to population displacement) and disruption of wildlife movement (not just water) and, overall, all the surrounding ecosystem. A notable example of major environmental impact is the destruction of the Seven Cascade Falls on the border 100 day loans between Brazil and Paraguay in 1982 by the Itaipu dam . Today the second, it was the largest dam in the world when it comes into operation. Two weeks is enough for the artificial dams dam submerge the region falls. The Government of Brazil went on to blast the remaining amount out of the water, destroying one of the major wonders martial arts denver of the natural world. Note that in the proposed dams, hydroelectric power generation is often complementary to other purposes such Phen375 Reviews as flood control and their consequences, improving the navigability of a waterway, the water channels, stockpiling water for irrigation, tourism … The project Belo Monte dam is strongly criticized by Indians whose Chief Raoni and environmentalists because the dam will cause deforestation of a portion of the Amazon rainforest.

Small Hydro Jump to: navigation , search

Francis turbine with its generator A small hydroelectric plant is a power plant using the water power to generate the electricity on a small scale. This electricity can be used to power remote sites (one or two houses, a workshop of a craftsman, a barn …) or sold to a public distribution network. Summary  [ hide ] 1 Principle of operation 1.1 Hydraulic vortex 2 Power 3 Notes and references 4 See also 4.1 Related Operating Principle

Main article: Hydroelectric Power . The operating principle of a small hydroelectric plant is to convert the potential energy of a waterfall in mechanical energy through a turbine , then electricity through a generator . The installed capacity of the plant depends suspension lift kits on the flow of water turbines and the height of fall . Hydraulic vortex  This type of power developed in Austria , with huge potential and low-technology, does not need a big hill to work. A water intake channel of engagement ring a river basin to a circular rotation of a rotor diameter with a pitch in the center of the basin, allows the production of 80 to 130 MWh per year, depending on the amount of water and the depth of the basin. The rotor runs through the strong current and gravity, resulting in a generator that will produce electricity. A hydraulic vortex can operate from a drop height of 0.7 meters and an average amount of water to 1000 liters per second. This technology has practically no danger to the fish as they can safely go through the small hydroelectric plant both above and below 1 . A first hydraulic vortex in Switzerland was opened in Schöftland in the canton of Aargau in Switzerland , September 25, 2010 2 , 3 , 4 . Power

Dam Jump to: navigation , search For items uses, see Dam (disambiguation) .

This article does not cite enough sources  (August 2008) . If you have books or articles reference or if you know of quality websites dealing with the theme here, thank you for giving complete article useful references to its verifiability and linking to the section “Notes and references ” . ( Amend section )

Hoover Dam , USA

Dam Limmern ( Glarus , Switzerland )

Spillway dam Matsumoto (Nagano Prefecture, Japan)

The ecology of river banks of artificial water bodies can be disrupted by sudden changes in level. A dam is an engineering structure built across a river and intended to regulate the flow of the stream and / or to store water for various uses such as flood control, irrigation, industry, hydropower, fish, drinking water supply, etc.. By extension, called dam obstructions placed on an axis of communication, designed to allow Jewish Wedding Gifts control over the persons and / or goods that circulate (roadblock military checkpoint). However, there is no uniform definition of “dam”. The only existing census is that of “large dams” regularly maintained by the International Commission on Large Dams (ICOLD). When the dam is submersible, it is referred to floor , threshold or dam  , the latter term is preferred to the dam when it comes to channel a flow and not to create a body of standing water. A dam river allows such flow control of a river or a river (thus favoring the river traffic), the irrigation of crops, on prevention of natural disasters ( floods , floods ), through the creation of lakes artificial or tanks. A dam also allows, under certain conditions, the production of motive power (water mill) and electricity – it is called Dam hydroelectric – at an acceptable economic cost, environmental cost is more discussion, see about it the écopaysagère fragmentation , siltation upstream of the dam, degradation of water quality. However, a more ambitious project, the consequences are more serious: by flooding entire valleys, the construction of a dam can cause both human upheaval by forcing entire populations to move, and have a significant environmental impact fundamentally changing the local ecosystem. In most cases, the law or customary law impose an instream flow (minimum flow available to downstream users and the maintenance of the aquatic ecosystem and species dependent). Summary  [ hide ] 1 History 2 Some examples of large dams in the world 3 Construction Techniques 3.1 General 3.2 Elements of calculation 3.3 Hydraulic Studies 3.4 Types of dams 3.4.1 Dam weight 3.4.2 Embankment dam 3.4.3 Arch Dam 3.4.4 Dam buttresses or multivoûtes 3.4.5 Dams mobile needle 3.4.6 Dams mobile casement 3.4.7 Other types of dams 4 Elements 4.1 Machines hydroelectric 4.2 Instrumentation and control tools 4.3 e cigarette spillway 4.4 Basins energy sink 5 Life of dams 5.1 Maintenance of Dams 5.2 Disasters 03.05 Earthquakes 5.4 The control dams in France 5.5 Decommissioning of Dams 6 Environmental impacts 6.1 Negative Impacts 6.2 Positive Impacts 7 Appendices 7.1 Bibliography 7.2 Related 7.3 car transport External Links 8 Notes and references History

 

The dam Roman Cornalvo in Spain is still in use after two thousand years.

Strings of lakes created by dams on small streams, the Middle Ages to the xviii th  century (France, according to the map of Cassini) The dams are probably in prehistoric times (drinking water supply, irrigation, fish ponds, fish farms). According to N. Schnitter-Reinhardt, the oldest known dam is a gravity dam built near Jawa in Jordan , built in the late 4 th millennium BC 1 Herodotus mentions a dam built by the pharaoh Menes , founder of the first Dynasty in Kosheish to supply the city of Memphis . A dam with a length of 115 meters was built in the valley of Garawi in Egypt around 3000 BC. AD The first known dam failure is the Sadd El kaffara safety defensive driving on the Wadi Garawi, 30 km south of Cairo . It would have occurred between 2650 and 2465 BC It was probably the breaking of the dam that has stopped construction for a millennium 2 . In 560 AD. AD, the Byzantine historian Procopius of Caesarea was a mention of arch dam upstream masonry (dam Daras). The Romans built dams, for example, two dams in Spain, near Merida , dams of Proserpina and Cornalvo from a height of 12 to 19 m , built around 25 BC, or yet, in Portugal , the Belas Roman dam . But it’s the Middle Ages they were highly developed in Europe to power water mills. Sometimes they seem to have been based on accumulated sediments upstream of natural jams, or the scene of beaver dams which keeps track names (for example in France with the word forebay and Goosander (formerly beaver) that may be related, or with common names such as Beuvry (an ancient name for beaver) or Labeuvrière (the “castorière”). The old maps of Cassini for example, bear witness to the many small dams rivers made ​​by local farmers or monks, to conserve water and raise fish or for retting flax or hemp . By keeping the volume of water and a water level higher in the dry season, the dams were also able to buffer fluctuations in summer groundwater (because all other things being equal, it is the water level that controls the speed percolation, cf. Darcy’s Law ). At the xvi th  century , the Spanish realized large dams in masonry. Most notable was that of Tibi, at 18 km north of Alicante , Denver Divorce Attorney built in 1594 . Top 45 m, it is still used. The first modern arch dam was built by François Zola , the father of Emile Zola , between 1843 and 1859 close to Aix-en-Provence . Some examples of large dams in the world

Main article: List of the largest hydroelectric dams .

Dam on the Toutle River (Cowlitz County, Washington (USA), built in 1986-1989 by the American military genius not to retain water, but to store some of the sediment from the major eruption the volcano of Mount St. Helens in 1980. the Hoover Dam in the United States (1931-1935) dams of chicago dui attorney Aswan on the Nile in Egypt The Inga dam on the Congo in the Democratic Republic of Congo the Itaipu dam on the Parana , on the border between Brazil and Paraguay the Robert-Bourassa in Quebec the Kapanda dam on Kwanza in Angola the Three Gorges Dam in China the dam of Great Dixence in Switzerland the Ataturk Dam on the Euphrates in Turkey the Daniel-Johnson dam on the Manicouagan in Quebec the Guri Dam in Venezuela the Nurek cna certification Dam (300 m) in Tajikistan is the Bankruptcy highest in the world. Construction techniques

General  A dam is subject to several forces. The most significant are: the hydrostatic pressure exerted by water on the siding exposed to water retention; the uplift ( buoyancy ) exerted by the water percolating into the body of the dam or foundation; any forces caused by the seismic acceleration . To withstand these forces, two strategies are used: construct a work sufficiently massive to resist by its sheer size, it is rigid (concrete gravity dam) or flexible (embankment dam); a dam capable of these efforts to see the shores or bedrock resistant (arch dam, multiple-arch dam …). Computing elements  A dam is subjected to a horizontal force due to the pressure exerted by water on its surface submerged. The hydrostatic pressure p at each point depends on the height of water above that point. p = ρ g h where ρ is the density of water, approximately 1000 kg / m³ g is the gravity , about 9.81 m / s ²  , h is the height of water above the point considered. The force F resultant is the integral of the hydrostatic pressure exerted on Plastic Storage Containers the submerged surface of the dam.

This formula does not fit “by hand” for dams complicated geometry. However, an analytical expression can be obtained for an element of gravity dam (a “plot”, width L and height submerged constant H ):

where:

We see in this formula that the pressure exerted by water on a dam increases with the square of the height of the reservoir (which is true for any type of dam). It depends of course not the volume of water stored in the reservoir. The point of application of this force is at the centroid of the diagram of pressure, usually one-third of the height of restraint. The above calculations relate only to the dams of rigid material (concrete, masonry …), regardless of type (weight, arch, buttress …). However the integration with studs dams interest only type weight or buttresses , which are governed by the static solid . For the arches, the efforts being carried laterally through mechanisms of bending and compression, one studs calculation only takes into account that the vertical forces is not enough and it is necessary to use the strength of materials ( elastic deformation ) and often advanced numerical methods ( finite element method linear or nonlinear). However, in respect of embankment dams (soil, earth, rock fill, embankments …), the calculations are related to slope stability calculations of embankments which must take into account the state of saturated or unsaturated embankments . Hydraulic studies  In hydraulics , the model is widely used for studies of fluid mechanics of structures such as ports , levees , dams , etc.. Used in these cases the similarity of Froude number . Digital models two-or three-dimensional are also often used. Types of dams  Gravity dam

A hollow gravity dam: the dam upstream of Aussois in Savoie

Gravity dam A gravity dam is a dam whose own weight is sufficient to withstand the pressure exerted by the water. The dams are often relatively thick, the shape is usually simple (their section is similar in most cases a right triangle. There are two main types of gravity dams, concrete dams weight and dams embankments (the latter are also generally not qualified as gravity dam but embankment dam). Although arch dams and buttress to require less material than gravity dams, they are still used today. The concrete gravity dam is chosen when the rock site (valley sides) is strong enough to support such a book (otherwise it uses the embankment dams), and when the conditions for building an arch dam are not met (see below). The choice of technique is first geological pretty good rock foundation is required. But we must also have building materials (aggregates, cement) nearby. The technology of gravity dams has evolved. Until the beginning of xx th  century (1920-1930), the gravity dams were built of masonry (there are many dams of this type in France, including water supply and waterways). Later, conventional concrete that has emerged. Since 1978 , a new technique has replaced the conventional concrete. This is the roller compacted concrete. It is a concrete (aggregate, sand, cement, water) with little water, which has a consistency not liquid and granular. It is set pro flight simulator up like a landfill, with earthmoving equipment. It presents the main advantage of being much cheaper than conventional concrete. The Great Dam Dixence in Switzerland , operated by Alpiq , is the highest gravity dam in the world (285 m). Dam embankments

Along 2123 m , the dam KA-5 is a work in riprap 47 m in height that closes the West Branch of the Caniapiscau River , in northern Quebec. The dam consists of a core of moraine, several filters soft stone, the whole being covered with a layer of blocks of one meter. Its volume is 5.62 million m 3 3 . We call all the dams fill dams consist of a loose material, it is very thin or very coarse (rockfill). This family includes several categories, very different. In differences in the types of materials used and the method used to seal. The dam is a homogeneous embankment dam constructed of a material sufficiently tight (clay, silt). It is the oldest technique of embankment dams. The clay core dam has a clay core (which seals), supported by recharges made of materials more permeable. This technique has at least two advantages over the homogeneous dam: (1) charging materials are more resistant than clay materials, we can build steeper slope and (2) is better controlled runoff percolating into the body of dam. The dam-core moraine is often used in areas marked by the retreat of glaciers. These works generally consist of an impervious core of moraine, recovered near the site, which is protected by granular filters. Cutting one type of rockfill dam also includes a transition area between the filter and refill 4 . Some cousins ​​core dams: dams embankment center wall sealed (concrete diaphragm wall, concrete wall sands). More recently, the family of upstream dams mask. Sealing is ensured by a “mask”, built on the upstream face of the dam. This mask can be concrete (it is currently building a number of very large dams spa covers and rockfill mask reinforced concrete), asphalt concrete, or consists of a thin membrane (the most common: PVC membrane, bituminous membrane). The dam Mattmark in Switzerland , that of Šance in the Czech Republic are of this type. In France , the dam of Serre-Ponçon (second maximum restraint to Europe ) is an embankment dam. Rockfill dams are most common in the park dam Hydro-Quebec. They represent 72% of the 600 dams operated by the company in 2002 5 . Arch dam  Main article: Arch dam .

Arch dam

An arch dam: the dam Monteynard The Wire Cart Covers thrust of the water is transferred to the sides of the valley through a concrete wall curved horizontally and sometimes vertically (then called on the vault with double curvature ). The technique of arch dam requires a rather narrow valley (although arch dams were built sometimes in valleys wide enough, pushing the technology to its limits) and a good rock foundation. Even when these conditions are met, the arch dam is now often challenged by the concrete gravity dams or rockfill dam, the implementation may be more mechanized. By the lack of material used, it is obviously a very satisfactory technique economically. However, the largest dam disaster lived in France ( Malpasset , above Fréjus , on 2  December  1959 ) involved an arch dam during impoundment and is the foundation (and not the dam itself same) has not supported the forces applied by the restraint. Before this accident (and for some even today), the arch is considered the most reliable dams. Malpasset is the only known case of a broken arch dam. There are also a number of dams with arches as the Hongrin dam in Switzerland . Buttress dam or multivoûtes

The Multiple arch and buttress dam Daniel-Johnson.

Buttress dam When the supports are too remote, or when the material is so compact that local extraction is almost impossible, the technique of the dam buttress dam allows for a large economy of materials. The flat wall or multivoûtes (Vezins, or Migoëlou Bissorte) based on concrete buttresses reinforced concrete embedded in the foundation, who delay pushing water on the foundations and lower on the shore. One of the most important examples of this type is the Daniel Johnson Dam in Quebec , completed in 1968 as part of the project Manic-Outardes . Back to 214 m wide and 1312 m , the dam, designed by Andrew Coyne 6 , is supported by two central buttresses separated by 160 m at their base. The side free iPhone ringtones arches 13 are half-inclined cylinders that have 76 m on center. Beyond aesthetic considerations, Hydro-Québec has chosen to build a dam in vaults and buttresses for economic reasons. According to the study design, the construction of the project required a little over 2.2 million cubic meters of concrete, which is five times less than a gravity dam 7 . Weirs needle

Poiree system: 1  = needles, 2  = support 3  = gateway, 4  = farm, 5  = pivot, 6  = knocker, 7  = delete

Needle dam in Givet – Removal of a needle The weir or constant , has a limited height, it is generally built downstream of the river courses, preferably where the slope is the lowest. Generally used this type of dam in the development of estuaries and deltas. Depending on the type of building the weir can be:

Needle weir, Fumay , Ardennes The needle weir , designed by engineer Charles François Antoine Poiree in 1834, which inspired the old sluices , the system spread across the width of the course, greatly improving river navigation from the middle of the xix th  century. The first was established by Charles François Antoine Poiree on the Yonne at Basseville, near Clamecy ( Nièvre ). The Poiree system consists of a curtain of planks placed vertically side by side blocking the river. These planks or needles of a section of 8 to 10 cm long and 2 to 4 m, depending on the barrages, bear against a target (or knocker) the write off (the bottom) and a bridge made ​​of metal farmhouses . These trusses can be rotated to give way on the bottom in case of flooding and allow free passage to the waters. Trusses are connected by a Chicago Criminal Lawyer support bar that holds the needle and a bar meeting , in addition they are the gateway to maneuver. The hands at the top have a form that allows easy entry. Nevertheless it is a tedious, long and dangerous (it takes several hours and the work of several men to carry out the task). Although this type of dam to be replaced by more ppi reclaim modern techniques and machines, even on some existing dams, the wooden needles are replaced by aluminum needles filled with polystyrene (for buoyancy if dropped in the river), d a much lower weight and easier to maneuver. To erase the bottom of the river ( threshold (dam) ) so that the total flow in the intermediate position or to denver auto accident lawyer create a weir . Weirs swing  To fly or door-to-vertical axis , such as dams modern Dutch ( Maeslantkering ), or the door to Leonardo closing the canal port of Cesenatico to prevent high tides from invading the land.

1  = leaf, 2  = overflow, 3  = flap valve, 4  = valve area Casement horizontal axis with the possibility of escape by air when the flow becomes critical, which avoids an obstacle to the flow of water in times of flood. This type of dam is generally used to prevent salt water up the estuary, as Volta Scirocco in Italy . The fixed part is a platform (or invert) sealed. A large valve area, which in fully closed position determines a fighter based on the platform, while at full lift position, it leaves the flow completely free. A valve flap mounted on the upper generatrix of the valve area, which adjusts the flow in the weir and the desired water level upstream of the dam. The flow of water can occur from under the wing when the valve is raised to lower sector (which also helps clean the surface of the platform) or the top weir when the valve greater part is lowered.

Drain by gravity: A  = Lagoon, B  = sea 1 = concrete base, 2 = leaf valve, 3 = air injected, 4 = water expelled Weir gravity , a theory very simple operation, the valve gravity has few mechanical parts. This is a fighter, a sort of hollow shell built around a hinge attached to a concrete pad. In the rest position the envelope fills with water and falls of its own weight on the floor. In the active position of the injected air displaces water and allows the leaf to go back by gravity. The height depends on the amount of air blown. Such a process is under the Project Mose must protect the lagoon of Venice high water of the Adriatic ( Acqua alta ).

New valves, valve dam under construction in Givet . Weir, hopper , an operation similar to mobile gravity dam above with the difference that is driven by two hydraulic cylinders 8 located on either side of the valve. It fully complies with its function: to regulate the flow of the river to maintain a substantially constant level in the forebay. Its main drawback is that it is exceedingly dangerous for the tourist boat. The fish can go up when the river is high water and the valve all the way down 9 . Other types of dams

A dam made by hand on a stream. There are other types of dams, generally smaller. The tailings dams are dams with mining residues to create a storage area of the rock. Dams are mounted as and when the mine. They are related to embankment dams. The mountain dams are structures designed to fight against the effects of torrential erosion. These are structures built across the streams. They can interrupt (partially or completely) sediment transport and may also determine the longitudinal profile of thalweg lowering aggression flows. The filter dams are structures built of stone free through a trough or low ground where runoff is concentrated during heavy rains. The dam serves to slow the speed of flood waters, and Epand these waters over an area at the upstream side, in which the action is increased infiltration and sediment are deposited. The area flooded is a cultivated field on which are obtained in good yields through better availability of water and nutrients for crops such as sorghum . At the same time, the erosion in the gully thalweg is stopped or avoided 10 . Components

Depending STD Test on the intended use, the dam will include several elements from the following: Hydro machines  Main article: turbine . Instrumentation and control tools  Spillways

The weir tank Kangaroo Creek in South Australia , during the flood of November 2005. The weir is part of the dam for discharging a flow from the reservoir upstream to a discharge channel. It will be used in particular in case of flooding which could endanger the dam upstream which increase the level excessively. Some spillways are equipped with a valve system to control the flow restored, the other weirs, so-called “line free” are more reliable in regard disruptions or mechanical failures. The weir is one of the main systems for the security works. There are several types of weirs including: the main weir evacuates flood the most common auxiliary spillways can evacuate the excess flow of principal spillway, the emergency spillway which is set to evacuate exceptional floods (up to flood occurrence very low, with return periods of more than 10 000 years for some books). The design of a spillway must meet trade-off between the dimensions of the weir, the amount of water stored and the amount of water discharged. More the latter, the greater the spillway should be wide or deep. The weir may be faced with erosion problems, sometimes caused by cavitation or turbulence, which can lead to its destruction. The management of the flood is a trade-off between throughput sent downstream, and the risk of drowning upstream of the reservoir by the rise of impounded water. The French rules not to aggravate the maximum flow rate (peak) of the flood. Energy sink basins  Main article: stilling basin . Used to dissipate the energy in water flowing through the discharge channel. The basin energy dissipator helps prevent erosion downstream. Life of dams

Maintenance of dams

Accumulation of natural and anthropogenic debris against the wall of a dam.

The remains of the dam Malpasset destroyed December 2, 1959. A dam wall is not just a more or less solid. It is not inert and is subject to seismic and technical under several criteria. The book lives, works and tires according to the forces to which it is subjected. Any dam may be exposed to four types of risk: defects in maintenance and control, in view of the obsolescence of materials; flooding; unevenness, movements or landslides; earthquakes, the reference is 3.5 on the Richter scale. The obsolescence of materials is mainly due to the degradation of the material concrete, Relevant Life Policies which may be subject to two conditions: the alkali-aggregate reaction (suffered by the Chambon dam, France) and delayed ettringite formation (suffered by the dam Bimont, France) 11 . Generally, it is estimated that during the 20 th  century, 1% of dams around the world have broken 11 . For reasons of maintenance works, dams are regularly inspected. Each year, the external appearance of the dam is considered, and periodically (every 10 years in France) withholding water is drained to allow access to both the lower part of the work and equipment ( water pipes, gates, valves, etc.).. Works involving public security are auscultated by the sensors to measure their behavior (measures displacement, water pressure, flow …). Its state depends on the safety of populations living downstream. Provided the probability of rupture is ziPhone extremely low, statistically, a break a year on a global fleet of 16 000 dams, China excluded. In Europe , the probability is even lower. In fact the danger is greatest during the first filling, however, the risk is much lower for concrete structures for those in landfills. In France , regulations relating to safety and the safety of hydraulic structures is payday loan provided by Decree 2007-1735 of 11 December 2007. The latter has established a new classification of dikes and dams and clarified the steps to ensure their control, their application security and maintenance. Dams built in the Alps in the years  1950 and 1960 at the height of the golden age of white coal , are now managed in a phase of aging requires maintenance costs ever higher . EDF believes that most of hydraulic reach only half of their life expectancy but announced a major investment program for maintenance and rehabilitation. According to the report of the OPCEST (Parliamentary Office for Evaluation of Scientific and technological) of the French July 9, 2009, the main concerns lie less in the great works in the multitude of small dams in France for which maintenance levels and control are inadequate. Disaster  A design flaw or maintenance can lead to disaster: if the dam bursts, while the water reservoir is relatively large, a tsunami tidal wave may break on people living downstream, more or less channeled by the topography of the river on which the dam was located (see section Catastrophe ). In France , such a catastrophe occurred in 1959 near Frejus, in Malpasset Dam . The film The Madness of men (2001) recounts the trials and tribulations of dam Vajont in Italy in the early 1960s. From a real fact, the film shows the causes and sequence of events that led to a landslide of 270 million cubic meters in the waters of the reservoir dam. The giant wave that followed was 2000 victims, 9  October  1963 . The principal has a dam-related disaster is breaking the pikalainat Banqiao Dam in China in 1975 that killed 26 000 people directly because of the flood. Earthquakes  Earthquakes are among the events that may affect the stability of dams. However, historically, the ruptures caused by earthquakes are very few compared to those due to design flaws. In France, large dams are the subject of a computer simulation of behavior in the case of the strongest historical earthquake known in the region (often estimated from old documents, but not going much beyond 500 years). Thus the design basis earthquake in the Pyrenees is the June 21, 1660, a magnitude estimated at around 6 and the intensity was IX in Bagneres-de-Bigorre ). Such a quake today would cause significant damage in the Hautes-Pyrenees, but is nevertheless supported by all major dams [ref. needed] . The most common failures were for the embankments of moderate size, built with materials sandy or silty, or based on soil of this nature, it may indeed develop in this case a phenomenon called thixotropy , which is losing all resistance to sand or silt saturated. Control dams in France  The safe operation of dams is the civil and criminal liability of its operators. However, given the risk and magnitude of potential consequences, the area is controlled by state services. The dams in the hydroelectric concessions are part of the Public Domain Hydroelectric. The DREAL (ex-DRIRE, Energy Division) is responsible for the supervision of the works owned and assigned by concession to a developer / operator. The START (Interservice Mission on Water, in the DDEA) are in charge of the works carried and operated under the authorization (small hydro, and works without using energy). After the catastrophe of Malpasset (December 2, 1959), the Ministry of Public Works has prepared Circular No. 70-15 of August 14, 1970, framing the missions of the inspection and obligations of operators. The Ministry of Industry Circular 70-15 completed by a circular BMI (medium-sized dams) May 23, 1995, applicable only to licensed works. Meanwhile, the CTPB was created in 1963 (Permanent Technical Committee on Dams), bringing together leading French experts, and since 1992 the largest dams are subject to a PPI (special intervention plan) which analyzes the risks (including earthquakes and landslides type dam Vajont ). With the opening of the electricity market and the changing status of the main operators (EDF, CNR, SHEM ) flyers became ineffective, and after joint discussions new regulation has been defined by Order No. 2007-1735, taking by accentuating the provisions in place to listen dams and analyze their behavior. First, the start of 2008 sees the classification of all dams, hydroelectric or not, in four classes: A for dams over 20 m in height above the natural ground; B for dams over 10 m and of a BMI greater than 200; C for dams greater than 5 m and of a BMI greater than 20; D for the other dams higher than 2 m. This report [Contradiction!] BMI =  H 2  .  V 1 / 2 [Contradiction!] , where H is the height above the ground surface and V the volume (in millions of cubic meters) retained by the dam, combines risk (high) and the consequences of a possible rupture (volume). It was introduced by André Goubet, former president of CTPB, in 1995 for an extension of the filing of the time, which in December 2007 is the latest development. Class A dams are subject to all the 10 years of a risk assessment (EDD), a full technical review (ETC, replacing the old ten-year inspection) and a safety review (PSR). Class B dams are subject to a risk assessment every 10 years. All dams classified (A, B, C and D) must have: a set of flood; a set of auscultation and monitoring (CSA); a device adapted auscultation. They are subject to: an annual report of the operator, including all significant facts to safety; analysis biennial measures auscultation; a systematic reporting of any significant event for safety hydraulic (Eish). Decommissioning of dams  The dismantling of a dam is not a matter of ecology, but reaching the life limit of the dam, even if it can, in part, to river ecosystems to function more satisfactorily. The initial free ipad investment by the manufacturer, again to satisfy a need for public services (drinking water, irrigation, electricity) with means of sustainable development is not intended to be abandoned or destroyed. Note the lack of funding for decommissioning of these fish use (mainly recreational), and lack of planning for sustainable ways to replace the energy lost as well. In France , the dam Poutès (Haute-Loire) and could be dismantled. The first hydroelectric dam to be dismantled is the Kernansquillec to Plounévez-Moëdec in the Cotes d’Armor. “In 1996, the demolition of the hydroelectric dam, a first in France on a salmon river, the landscape has sunk to resurface” 12 . Similarly, because no longer meeting the obligations of public safety, the Piney Dam (drinking water, municipal project management) in Saint-Chamond was safe in 2000 by digging a sluice at the foot of the dam. Environmental consequences

Main article: Environmental impact of dams .

Large dams are powerful factors in ecological fragmentation for migratory fish. Negative impacts  A dam can generate an ecological fragmentation , when a brake or blocking the migration of aquatic species. There is requirement in some countries in recent years on new work (in France, on the rivers classified as “migratory” since the Act chiropractic marketing “Fishing” No. 84-512 of 29 June 1984) to build fish ladders . These are still rare on old books or on the rivers where the presence of migratory species is not identified. Conversely, some works are equipped with no obligation, by the will of the operator. Some fish ladders poorly designed or poorly constructed can be very effective. Fish transport truck may be the alternative chosen, for example on the Garonne between Carbon and Camon , where the sequence of five major dams would have required expensive equipment and a very rough ride for the migratory. The fish are “trapped” at one end of the chain, identified and transported by truck to the other end. A dam can generate hydraulic modifications, when upsets the natural flow and seasonal streams, affecting the water table and transfer of suspended solids and sediments. He has delayed effects on the ecosystem of a large area due to the flooding of the area upstream , and the strong modification of the flow regime of waters of downstream , and the change in the quality of caused by water retention. A dam may cause a change in the ecological structures and facilitate the ” biological invasions “. An ecosystem sub-natural and more or less balanced is reconstituted in these areas more or less quickly (within about 30 years, the ecosystem would be recreated to 99% [ref. needed] , including in the downstream old dry areas). However, this ecosystem is never identical to the original: the disappearance of the current upstream, and the sharp decrease in the downstream flow, and the disappearance or smoothing seasonal flow usually causes the disappearance of some native species . In addition, a study 13 published in September 2008 confirmed that the United States in the watershed, the artificial environments that are selected lakes were much more conducive to the development of aquatic species known as “  invasive  “than natural lakes, This study sought to correlate the Great Lakes region of the importance of biological invasions with the physical chemistry of the water mass, the intensity and nature of water activities with the geographical distribution of five non-native species 14 . The study showed that the risk of biological invasion is (for the Great Lakes region) of 2.4 to 300 times higher in reservoirs than in natural lakes (around 2005/2008). This risk increased with time, and increases the threat to natural lakes because the increase in the number of withholding has affected almost everywhere decreased the distance between water “contaminated” and natural waters. This is where the man who plays the main role of peddler and especially Pieter TJ Johnson as one of the authors of the study, fishing and boating that promote the spread of many organizations, including the zebra mussel (hooked under the boat), the milfoil invasive clinging to boat trailers, and rainbow smelt and crayfish invasive sky that was used as bait (now banned). Positive impacts  A reservoir can be a host of migratory birds, breeding grounds of certain aquatic species, A reservoir may improve conditions for low water flow. Increasingly, hydroelectric dams are involved in support of low water, allowing a summer life of rivers also affected by numerous samples (authorized or not) to improve the cooling water, and dilution of pollution downstream . In France , since the same Fisheries Act 1984 , all the obstacles on the French rivers are required to leave the river 1 / 40 of the module (average speed), and 1 / 10 for all new structures or whose As is renewed. To end this unequal situation (posing many problems of flow variation on the same stream), the new law on water and aquatic environments 15 has set a st  January 2014 the deadline for issuing of 1 / 10 for all books. This however introduces LEMA except for high-head dams, ensuring the support of the grid, to which the minimum flow may be limited to 1 / 20 (a list to be fixed by order). Similarly, upon proof by an appropriate study, the flow can be modulated over the year (restricted diet). A reservoir may be a source of production of renewable energy in the case of a hydroelectric dam. Dams for irrigation or drinking water are also built to bring benefits for agriculture and water supply. These impacts must be weighed along with the disadvantages brought to the aquatic environment or the recreational fishery.