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33-521: Construction on the complex began in January 2007 after the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) issued an installation permit. One goal of the project is to reduce environmental impacts created by large reservoirs. The complex's five reservoirs will have a surface area of 15.36 square kilometres (5.93 sq mi). On August 5, 2009, the river was diverted through

66-475: A 12.48 percent angle. Once the water is discharged from the power station, it returns to the Paraíba via a 760-metre (2,490 ft) long tailrace channel. The project was featured on Build It Bigger during a season 8 episode. 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 the dammed river itself. In

99-439: A 28.8 megawatts (38,600 hp) power station with 2 x 14.4 megawatts (19,300 hp) Kaplan turbine -powered generators. The water diverted by the dam first enters channel C1 which is 1.9 kilometres (1.2 mi) long, 28 metres (92 ft) wide and 8 metres (26 ft) deep. After C1, the water moves into the 1,458-metre (4,783 ft) long tunnel T1 before entering the 1-kilometre (0.62 mi) long channel C2. After C2 and

132-443: 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 Despite being superseded by more modern engineering techniques such as hydraulic jumps in the mid twentieth century, since around 1985 interest in stepped spillways and chutes has been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

165-565: 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

198-459: 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

231-473: A spillway gate can result in the stranding of fish, and this is usually avoided. Intake tower An intake tower or outlet tower is a vertical tubular structure with one or more openings used for capturing water from reservoirs and conveying it further to a hydroelectric or water-treatment plant. Unlike spillways , intake towers are intended for the reservoir's regular operation, conveying clean, debris-free water for further use. An intake tower

264-460: 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

297-443: 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

330-403: Is typically made from reinforced concrete , with foundations laid in the river or lake bed. It has at least one water-collecting opening at the top, and may have additional openings along its height, depending on the purpose: towers for hydroelectric plants typically have only one inlet, while those in water-processing plants have multiple draw-off inlets. Near the bottom of the tower, depending on

363-474: The Anta Dam's spillway . The rate progress is such that the completion of construction is on schedule for commissioning in 2013. The Anta Dam began to impound its reservoir in late February 2013. All three generators went into operation by early June 2013. The project was completed almost three years behind schedule. Delays were attributed to increased costs, lengthy permit approvals and a court decision which delayed

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396-558: The Anta Reservoir from being filled. Water from the Paraíba do Sul is impounded at the 29.5-metre (97 ft) high and 260-metre (850 ft) long roller-compacted concrete Anta Dam before being diverting into a series of eight water channels, four water tunnels and five reservoirs totaling 26 kilometres (16 mi) in length. At the end of the circuit, the water is fed to a power station containing 3 x 101.3 megawatts (135,800 hp) Francis turbines . The Anta Dam itself supports

429-606: The Antonina reservoir before reaching the 203-metre (666 ft) long channel C7 and then into the Peixe reservoir which is created with the assistance of three dikes. After the reservoir, the water is transferred to intake channel C8 and from there into three 300-metre (980 ft) long penstocks which feed the Simplício Power Plant's three Francis turbines. The penstocks provide 80 metres (260 ft) of hydraulic head and are at

462-460: 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

495-520: 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 is full, operators can prevent an unacceptably large release later. Other uses of

528-407: 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

561-413: The dam construction and plant location, a horizontal or slanted outlet conduit takes the water from the tower into the plant. The most convenient location for an intake tower is in the proximity of the processing plant. In artificial lakes, those are typically placed near the dam. Lake bed near the dam also provides sufficient water depth to ensure substantial supply to the towers throughout the year, thus

594-437: 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

627-414: 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

660-432: The exposed towers can be regularly seen along the dams. When built near the shore, an intake tower is equipped with a service bridge, used to gain access for maintenance. Draw-off towers are intake towers specialized for drinking water reservoirs. They have multiple openings at various depths, typically equipped with valves, allowing drawing water only from the level where it is of highest quality. This article about

693-423: 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

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726-424: 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

759-431: 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

792-456: 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

825-414: 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

858-438: 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

891-424: 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

924-412: 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 is a structure used to control water release on

957-493: The third Calçado reservoir which is partially created by the project's largest dike of 75 metres (246 ft) in height and 400 metres (1,300 ft) in length. The Calçado reservoir uses an outlet works to remove any excess water from the reservoir and help maintain appropriate levels. Water from the reservoir then moves into the 73-metre (240 ft) long channel C6 which feeds the project's longest tunnel, T3, at 6.03 kilometres (3.75 mi) in length. From T3, water moves into

990-414: 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

1023-457: The use of a dike , the water forms the Tocaia reservoir before entering channel C3 which is 565 metres (1,854 ft) long. From C3, water is led into tunnel T2 and then to the 85-metre (279 ft) long channel C4 before reaching tunnel T2A. Water from T2A enters a valley and with the assistance of two dikes, creates Louriçal reservoir. From the reservoir, water enters channel C5 which directs it to

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1056-474: 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

1089-669: 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

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