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39-501: In 1864, Portugal and Spain signed the "Treaty of Limits" (ratified in 1866), which established the present international boundaries of the two nations. A treaty on transboundary rivers, clarifying issues regarding the use of such rivers, was signed and affirmed in 1912. A treaty regulating the development of hydroelectric facilities on the Duero River was signed in 1927. The Aldeadávila Dam was built by Spain pursuant to these treaties, and

78-410: A 53-metre (174 ft) high surge tank. The dam also contains more than 12 kilometres (7.5 mi) of tunnels which divert water to the electrical generation turbines. There are six penstock tunnels, each about 5 metres (16 ft) in diameter. The design of the penstocks and auxiliary spillways using these tunnels has proved to be an issue, however. Cavitation problems have damaged these tunnels in

117-443: A baffle of concrete blocks but usually have a "flip lip" and/or dissipator basin, which creates a hydraulic jump , protecting the toe of the dam from erosion. Stepped channels and spillways have been used for over 3,000 years. Despite being superseded by more modern engineering techniques such as hydraulic jumps in the mid twentieth century, since around 1985 interest in stepped spillways and chutes has been renewed, partly due to

156-401: A means of isolation of flows and regulate the flow of water while delivering it to waste management facilities or power plants. Penstocks are incorporated into the surface water management systems (drainage) of many landfill sites. Retention basins are constructed in order to store storm water, limiting the discharge from the site to its pre-development rate. Valved penstocks are installed at

195-565: A plunge pool, or two ski jumps can direct their water discharges to collide with one another. Third, a stilling basin at the terminus of a spillway serves to further dissipate energy and prevent erosion. They are usually filled with a relatively shallow depth of water and sometimes lined with concrete. A number of velocity-reducing components can be incorporated into their design to include chute blocks, baffle blocks, wing walls, surface boils, or end sills. Spillway gates may operate suddenly without warning, under remote control. Trespassers within

234-423: A spillway gate can result in the stranding of fish, and this is usually avoided. Penstock A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is of Scots origin, and was inherited from the earlier technology of mill ponds and watermills , with penstocks diverting pond waters to drive

273-402: Is 140 metres (460 ft) long, 18 metres (59 ft) wide, and 40 metres (130 ft) deep. The total volume of excavated material for all halls, rooms, and abutments was 600,175 cubic metres (785,000 cu yd). The structure has eight overflow gates which channel water into four spillways. The spillways incorporate side piers on the upstream face to more correctly channel water over

312-507: Is a structure used to control water release on a routine basis for purposes such as water supply and hydroelectricity generation. A spillway is located at the top of the reservoir pool. Dams may also have bottom outlets with valves or gates which may be operated to release flood flow, and a few dams lack overflow spillways and rely entirely on bottom outlets. The two main types of spillways are controlled and uncontrolled. A controlled spillway has mechanical structures or gates to regulate

351-419: Is also used in irrigation dams to refer to the channels leading to and from high-pressure sluice gates . Penstocks are also used in mine tailings dam construction. The penstock is usually situated fairly close to the center of the tailings dam and built up using penstock rings, short reinforced ring-like sections of pipe which nest one within the other when stacked and thereby control the water level, letting

390-460: Is designed like an inverted bell , where water can enter around the entire perimeter. These uncontrolled spillways are also called morning glory (after the flower ), or glory hole spillways. In areas where the surface of the reservoir may freeze, this type of spillway is normally fitted with ice-breaking arrangements to prevent the spillway from becoming ice-bound. Some bell-mouth spillways are gate-controlled. The highest morning glory spillway in

429-447: Is full, operators can prevent an unacceptably large release later. Other uses of the term "spillway" include bypasses of dams and outlets of channels used during high water, and outlet channels carved through natural dams such as moraines . Water normally flows over a spillway only during flood periods, when the reservoir has reached its capacity and water continues entering faster than it can be released. In contrast, an intake tower

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468-443: Is set by dam safety guidelines, based on the size of the structure and the potential loss of human life or property downstream. The United States Army Corps of Engineers bases their requirements on the probable maximum flood (PMF) and the probable maximum precipitation (PMP). The PMP is the largest precipitation thought to be physically possible in the upstream watershed. Dams of lower hazard may be allowed to have an IDF less than

507-539: The slimes settle out of the water. This water is then piped under the tailings dam back to the plant via a penstock pipeline. Inlet valves on the downstream end of penstocks are often used at mill sites to control the flow of water through the mill wheel, or to pen water into a mill pool. Similar structures which are not enclosed are head races or leats (non elevated), and flumes (elevated). Penstocks are commonly used in water management systems such as surface water drainage and foul water sewers. Penstocks provide

546-687: The Duero River flows is exceptionally deep and narrow, resulting in a reservoir that has a relatively small surface area for its immense size. In some ways, this limits use of the reservoir for recreational activities. However, the Aldeadávila Dam reservoir is a popular one for boating . Until the Alcántara Dam , also in Spain, was built in 1969, the Aldeadávila Dam was the largest hydroelectric power plant in Europe. As of 2018, and after some upgrades, it remains

585-460: The PMF. As water passes over a spillway and down the chute, potential energy converts into increasing kinetic energy . Failure to dissipate the water's energy can lead to scouring and erosion at the dam's toe (base). This can cause spillway damage and undermine the dam's stability. To put this energy in perspective, the spillways at Tarbela Dam could, at full capacity, produce 40,000 MW; about 10 times

624-604: The United States provided $ 8.9 million (about $ 67.2 million in 2010 inflation-adjusted dollars) in credits in 1958 to Iberduero to enable it to purchase six 119.7 Megawatt (MW) turbines and other electrical equipment for the power generating station, all of which were supplied by American firms. The dam won Spain an international reputation as a builder of very large dams. The dam's eye-catching, "ski jump" style spillways are its most noted feature, and have been called "outstanding" by leading dam engineers. The canyon through which

663-407: The capacity of its power plant. The energy can be dissipated by addressing one or more parts of a spillway's design. First, on the spillway surface itself by a series of steps along the spillway (see stepped spillway ). Second, at the base of a spillway, a flip bucket can create a hydraulic jump and deflect water upwards. A ski jump can direct water horizontally and eventually down into

702-437: The dam down a smooth decline into the river below. These are usually designed following an ogee curve . Most often, they are lined on the bottom and sides with concrete to protect the dam and topography. They may have a controlling device and some are thinner and multiply-lined if space and funding are tight. In addition, they are not always intended to dissipate energy like stepped spillways. Chute spillways can be ingrained with

741-440: The dam so that each spillway discharges the same amount of water. The spillways release their water slightly above the actual bed of the river, creating a waterfall effect when they are fully open. A spillway tunnel carved from granite in the right bank of the river augments the spillways and provides for additional overflow. The total spillway capacity is half that of Grand Coulee Dam in the United States. The Export-Import Bank of

780-532: The dam's design and construction (although it required more concrete to build), and more readily incorporated the spillways into the dam face. The dam's face is nearly vertical. Design work on the dam began in 1956, and construction completed in 1963. The structure was built by the Iberdrola Ingeniería y Construcción construction firm. Pedro Martínez Artola was the design engineer. The dam was built on high-quality granite rock. During construction, grouting

819-403: The dam's enormous tunnels. The final scenes of Antonio Mercero 's 1972 film, La cabina ( The Telephone Box ) were also filmed inside the dam. Terminator: Dark Fate filmed a scene at the dam. Fast X was also filmed at the dam. Spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee , typically into the riverbed of

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858-464: The dammed river itself. In the United Kingdom, they may be known as overflow channels . Spillways ensure that water does not damage parts of the structure not designed to convey water. Spillways can include floodgates and fuse plugs to regulate water flow and reservoir level. Such features enable a spillway to regulate downstream flow—by releasing water in a controlled manner before the reservoir

897-522: The demand for electricity is low (such as evenings, weekends, or during seasonal fluctuations), the dam's two pumped-storage generators can use its excess power-generating capacity to pump water back into the reservoir—enhancing reservoir capacity and storing water for periods when the demand for electricity is high. At the time it was constructed, the Aldeadávila Dam had the largest pumping station capacity in Europe. The dam has two diversion tunnels, each 1,400 metres (4,600 ft) in length. Each tunnel has

936-414: The difference in height between the intake and the outlet to create the pressure difference required to remove excess water. Siphons require priming to remove air in the bend for them to function, and most siphon spillways are designed to use water to automatically prime the siphon. One such design is the volute siphon, which employs volutes or fins on a funnel to form water into a vortex that draws air out of

975-423: The flood is sometimes expressed as a return period . A 100-year recurrence interval is the flood magnitude expected to be exceeded on the average of once in 100 years. This parameter may be expressed as an exceedance frequency with a 1% chance of being exceeded in any given year. The volume of water expected during the design flood is obtained by hydrologic calculations of the upstream watershed. The return period

1014-570: The largest in Spain, with a total output generating power of 1,142 megawatts (1,531,000 hp). The dam's original Aldeadávila I Power Station houses six 119.2-megawatt (159,800 hp) Francis turbines for a total generating output of 718.2 megawatts (963,100 hp). In 1986, the Aldeadávila II Power Station extension was completed, adding two 210.5-megawatt (282,300 hp) Francis pump-turbines , boosting generating capacity by 421 megawatts (565,000 hp). During periods when

1053-670: The mills. Penstocks for hydroelectric installations are normally equipped with a gate system and a surge tank . They can be a combination of many components such as anchor block, drain valve, air bleed valve, and support piers depending on the application. Flow is regulated to suit turbine operation and is cut off when turbines are not in service. Penstocks, particularly where used in polluted water systems, need to be maintained by hot water washing, manual cleaning, antifouling coatings, allowing waters to go anoxic , and desiccation used to dry fouling out so that it may slough off or become easier to remove through manual processes. The term

1092-416: The past. A 30-minute documentary about the dam, La presa de Aldeadávila , was produced by Iberduero (the power company that built the dam) in 1963. Several scenes in the 1965 David Lean film Doctor Zhivago were filmed at the Aldeadávila Dam. The dam's famous spillways were opened for the filming, and are shown in the motion picture open at full force. Another scene depicts workers walking into one of

1131-424: The rate of flow. This design allows nearly the full height of the dam to be used for water storage year-round, and flood waters can be released as required by opening one or more gates. An uncontrolled spillway, in contrast, does not have gates; when the water rises above the lip or crest of the spillway, it begins to be released from the reservoir. The rate of discharge is controlled only by the height of water above

1170-431: The reservoir's spillway. The fraction of storage volume in the reservoir above the spillway crest can only be used for the temporary storage of floodwater; it cannot be used as water supply storage because it sits higher than the dam can retain it. In an intermediate type, normal level regulation of the reservoir is controlled by the mechanical gates. In this case, the dam is not designed to function with water flowing over

1209-456: The river downstream. One parameter of spillway design is the largest flood it is designed to handle. The structures must safely withstand the appropriate spillway design flood (SDF), sometimes called the inflow design flood (IDF). The magnitude of the SDF may be set by dam safety guidelines, based on the size of the structure and the potential loss of human life or property downstream. The magnitude of

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1248-414: The spillway are at high risk of drowning. Spillways are usually fenced and equipped with locked gates to prevent casual trespassing within the structure. Warning signs, sirens, and other measures may be in place to warn users of the downstream area of sudden release of water. Operating protocols may require "cracking" a gate to release a small amount of water to warn persons downstream. The sudden closure of

1287-438: The spillway gates. Although many months may be needed for construction crews to restore the fuse plug and channel after such an operation, the total damage and cost to repair is less than if the main water-retaining structures had been overtopped. The fuse plug concept is used where building a spillway with the required capacity would be costly. A chute spillway is a common and basic design that transfers excess water from behind

1326-424: The system. The priming happens automatically when the water level rises above the inlets. The ogee crest over-tops a dam, a side channel wraps around the topography of a dam, and a labyrinth uses a zig-zag design to increase the sill length for a thinner design and increased discharge. A drop inlet resembles an intake for a hydroelectric power plant, and transfers water from behind the dam directly through tunnels to

1365-414: The top if it, either due to the materials used for its construction or conditions directly downstream. If inflow to the reservoir exceeds the gate's capacity, an artificial channel called an auxiliary or emergency spillway will convey water. Often, that is intentionally blocked by a fuse plug . If present, the fuse plug is designed to wash out in case of a large flood, greater than the discharge capacity of

1404-474: The use of new construction materials (e.g. roller-compacted concrete , gabions ) and design techniques (e.g. embankment overtopping protection). The steps produce considerable energy dissipation along the chute and reduce the size of the required downstream energy dissipation basin. Research is still active on the topic, with newer developments on embankment dam overflow protection systems, converging spillways and small weir design. A bell-mouth spillway

1443-669: The world is at Hungry Horse Dam in Montana, U.S., and is controlled by a 64-by-12-foot (19.5 by 3.7 m) ring gate. The bell-mouth spillway in Covão dos Conchos reservoir in Portugal is constructed to look like a natural formation. The largest bell-mouth spillway is in Geehi Dam , in New South Wales, Australia, measuring 105 ft (32 m) in diameter at the lake's surface. A siphon uses

1482-431: Was the final dam to be built by Spain on the section of river allotted to that country. The dam is 140 metres (460 ft) high and its cost was estimated in 1962 at US$ 60,000,000 (about $ 443.5 million in 2010 inflated-adjusted dollars). It was one of a series of very high dams built in Europe in the two decades after World War II; these were designed with a downstream face inclined toward the upstream flow. This simplified

1521-533: Was used to fill cracks in the rock which ran parallel to the dam's foundation, and on the Portuguese bank where two fractures in the rock occurred. The underground power station and tunnels were excavated using a mining procedure known as large-chamber stoping . The use of this technique for the Aldeadávila Dam is considered a textbook example. The turbine and generator hall, and the transformer hall were both cut from solid granite as well. The turbine and generator room

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