A dam is a barrier that divides waters. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates, levees, and dikes are used to prevent water flow into specific land regions. Floodgates are adjustable gates used to control water flow in reservoir, River, Stream, or Levee systems Dike (constructionEmbankmentA levee, levée, dike (or dyke) embankment, floodbank or stopbank is a natural or artificial LeveeEmbankmentDitch A dike (or dyke) levee, levée, embankment, floodbank or stopbank is a natural or artificial The tallest dam in the world is the 300 meter high Nurek Dam in Tajikistan. The Nurek Dam ( Tajik: Нерӯгоҳи обии Норак Nerūgohi obii Norak, Tajiki for Nurek Hydro-electric Station) is a large earth fill Dam Tajikistan (təˈdʒɪkɨstæn or /təˈdʒiːkɨstæn/ Тоҷикистон tɔʤikɪsˈtɔn or, Persian تاجیکستان taajikestaan officially the Republic of [1]
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History
The word dam can be traced back to Middle English,[2] and before that, from Middle Dutch, as seen in the names of many old cities. Middle English is the name given by Historical linguistics to the diverse forms of the English language spoken between the Norman invasion of Middle Dutch is a collective name for a number of closely related West Germanic dialects (whose ancestor was Old Dutch) which were spoken and written between 1150 [3]
Some of the grandest and largest dams were constructed in Ceylon (Sri Lanka). Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka ( Sinhalese:, இலங்கை known as Ceylon before 1972 is an Island Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka ( Sinhalese:, இலங்கை known as Ceylon before 1972 is an Island [4] Dams in Yodha Wewa and Parakrama Samudra of Sri Lanka were the largest until the 20th Century . Parakrama Samudra (or Parakrama's sea is a large ancient reservoir in Polonnaruwa, Sri Lanka. As per Needham, Abhaya Wewa is the oldest reservoir that was made by the use of a dam, which has been dated to 300 BC. ([5] Most of the first Dams were built in Mesopotamia up to 7,000 years ago. Mesopotamia (from the Greek meaning "land between the rivers" is an area geographically located between the Tigris and Euphrates rivers largely corresponding These were used to control the water level, for Mesopotamia's weather affected the Tigris and Euphrates rivers, and could be quite unpredictable. The Tigris is the eastern member of the two great Rivers that define Mesopotamia, along with the Euphrates, which flows from the mountains of southeastern The Euphrates ( ( Arabic: ar نهر الفرات; Turkish: tr Fırat Syriac: syr ܦܪܬ; Hebrew: he פרת The earliest recorded dam is believed to have been on the Sadd Al-Kafara at Wadi Al-Garawi, which is located about 25 kilometers south of Cairo, and built around 2600 B. C. [6] It was destroyed by heavy rain shortly afterwards. [6] The Romans were also great dam builders, with many examples such as the three dams at Subiaco on the river Anio in Italy. The Aniene River (formerly called the Teverone; in Latin Anio) is a 98 km River in Lazio, Italy. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest Many large dams also survive at Merida in Spain. Spain () or the Kingdom of Spain (Reino de España is a country located mostly in southwestern Europe on the Iberian Peninsula.
The oldest surviving and standing dam in the world is believed to be the Grand Anicut, also known as the Kallanai, an ancient dam built on the Kaveri River in the state of Tamil Nadu located in southern India. The Grand Anicut, also known as the Kallanai Tamil kall, stone anai, bund--> is an ancient Dam built on the Kaveri River The Grand Anicut, also known as the Kallanai Tamil kall, stone anai, bund--> is an ancient Dam built on the Kaveri River The Kaveri River ( Kannada: ಕಾವೇರಿ ನದಿ Tamil: காவிரி ஆறு also spelled Cauvery in English Tamil Nadu ( Tamil:, Country of the Tamils, t̪ɐmɨɻ n̪aːɽɯ is one of the 28 states of India. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country It was built by the Chola king Karikalan, and dates back to the 2nd Century AD. Karikala Chola ( Tamil: கரிகால சோழன்) was the greatest among the early Chola kings of the Sangam age in South India [7]
The Kallanai is a massive dam of unhewn stone, over 300 meters long, 4. The Grand Anicut, also known as the Kallanai Tamil kall, stone anai, bund--> is an ancient Dam built on the Kaveri River 5 meters high and 20 meters (60 ft) wide,[7] across the main stream of the Kaveri. The purpose of the dam was to divert the waters of the Cauvery across the fertile Delta region for irrigation via canals. The dam is still in excellent repair, and served as a model for later engineers, including the Sir Arthur Cotton's 19th-century dam across the Kollidam, the major tributary of the Cauvery. The land area irrigated by the ancient irrigation network, of which the dam was the centerpiece, was 69,000 acres (280 square kilometers). The acre is a unit of Area in a number of different systems including the imperial and U By the early 20th Century the irrigated area had been increased to about 1,000,000 acres (4,000 square kilometers).
Du Jiang Yan in China is the oldest surviving irrigation system included a dam that directed waterflow. Dujiangyan ( is an Irrigation infra-structure built in 256 BC during the Warring States Period of China by the Kingdom of Qin It was finished in 251 B. C. . In ancient China, the Prime Minister of Chu (state), Sunshu Ao, is the first known hydraulic engineer of China. Chinese civilization originated in various city-states along the Yellow River ( valley in the Neolithic era This article is about the government position For other uses see Prime Minister (disambiguation. Chǔ ( 楚) was a kingdom in what is now central and southern China during the Spring and Autumn period ( 722 - 481 BC) and Sunshu Ao (孫叔敖 was an ancient Chinese court minister serving the administration of Duke Zhuang of Chu during the reign of King Ding of Zhou ( Hydraulic engineering is a sub-discipline of Civil engineering concerned with the flow and conveyance of Fluids principally Water. He served Duke Zhuang of Chu during the reign of King Ding of Zhou (606 BC-586 BC), ruler of the Eastern Zhou Dynasty. King Zhuāng of Chǔ (楚莊王 (died 591 BC was leader in the state of Chu and one of the Five Hegemons in the Spring and Autumn Period of Chinese King Ding of Zhou ( ch: 周定王 Pinyin zhōu dìng wáng or King Ting of Chou ( Wg) was the twenty-first sovereign of the Chinese Zhou The Zhou Dynasty ( POJ: Chiu Tiau 1122 BC to 256 BC was preceded by the Shang Dynasty and followed by the Qin Dynasty in China. His large earthen dam flooded a valley in modern-day northern Anhui province that created an enormous irrigation reservoir (62 miles in circumference), a reservoir that is still present today. Anhui (in Chinese: 安徽 Ānhuī) is a province of the People's Republic of China. Irrigation is an artificial application of water to the soil usually for assisting in growing crops [8]
In the Netherlands, a low-lying country, dams were often applied to block rivers in order to regulate the water level and to prevent the sea from entering the marsh lands. The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands Such dams often marked the beginning of a town or city because it was easy to cross the river at such a place, and often gave rise to the respective place's names in Dutch. Dutch ( is a West Germanic language spoken by around 24 million people 22 million of which are from the Netherlands, Belgium and Suriname For instance the Dutch capital Amsterdam (old name Amstelredam) started with a dam through the river Amstel in the late 12th Century , and Rotterdam started with a dam through the river Rotte, a minor tributary of the Nieuwe Maas. Amsterdam (pronounced) is the capital and largest city of the Netherlands, located in the province of North Holland in the west The Amstel is a river in the Netherlands which runs through the city of Amsterdam. Rotterdam (pronounced) is the 2nd-largest City by population in the Netherlands, located in the province of The Nieuwe Maas (English New Meuse) is a river branch of the Rhine-Meuse delta in the Netherlands. The central square of Amsterdam, believed to be the original place of the 800 year old dam, still carries the name Dam Square or simply the Dam. Dam Square, or simply the Dam (de Dam is a Town square in Amsterdam, the capital of The Netherlands.
Types of dams
Dams can be formed by human agency, natural causes, or even by the intervention of wildlife such as beavers. Beavers are two primarily nocturnal semi-aquatic species of Rodent, one native to North America and one to Europe Man-made dams are typically classified according to their size (height), intended purpose or structure.
By size
International standards define large dams as higher than 15 meters and major dams as over 150 meters in height. [9]
By purpose
Intended purposes include providing water for irrigation or town or city water supply, improving navigation, creating a reservoir of water to supply industrial uses, generating hydroelectric power, creating recreation areas or habitat for fish and wildlife, flood control and containing effluent from industrial sites such as mines or factories. Irrigation is an artificial application of water to the soil usually for assisting in growing crops Water supply is the process of self-provision or provision by third parties of water of various qualities to different users Hydroelectricity is electricity generated by Hydropower, ie the production of power through use of the gravitational force of falling water A habitat (which is Latin for "it inhabits" is an Ecological or environmental area that is inhabited by a particular Species. Flood control is a feature of many communication protocols designed to prevent overwhelming of a destination receiver Effluent is an outflowing of water from a natural body of water or from a man-made structure Mining is the extraction of valuable Minerals or other geological materials from the earth usually (but not always from an Ore body Few dams serve all of these purposes but some multi-purpose dams serve more than one.
A saddle dam is an auxiliary dam constructed to confine the reservoir created by a primary dam either to permit a higher water elevation and storage or to limit the extent of a reservoir for increased efficiency. An auxiliary dam is constructed in a low spot or saddle through which the reservoir would otherwise escape. On occasion, a reservoir is contained by a similar structure called a dike to prevent inundation of nearby land. LeveeEmbankmentDitch A dike (or dyke) levee, levée, embankment, floodbank or stopbank is a natural or artificial Dikes are commonly used for reclamation of arable land from a shallow lake. This is similar to a levee, which is a wall or embankment built along a river or stream to protect adjacent land from flooding. Dike (constructionEmbankmentA levee, levée, dike (or dyke) embankment, floodbank or stopbank is a natural or artificial A flood is an overflow of an expanse of water that submerges land a deluge
An overflow dam is designed to be over topped. A weir is a type of small overflow dam that can be used for flow measurement. WEIR (1430 AM) is a Radio station broadcasting a News Talk Information format
A check dam is a small dam designed to reduce flow velocity and control soil erosion. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Conversely, a wing dam is a structure that only partly restricts a waterway, creating a faster channel that resists the accumulation of sediment. A wing dam is a manmade barrier that unlike a conventional Dam, only extends partway into a River.
A dry dam is a dam designed to control flooding. A dry dam is a Dam constructed for the purpose of Flood control It normally holds back no water and allows the channel to flow freely, except during periods of intense flow that would otherwise cause flooding downstream.
A diversionary dam is a structure designed to divert all or a portion of the flow of a river from its natural course. A diversion dam is the term for a Dam that diverts all or a portion of the flow of a River from its natural course "Riverine" redirects here For the use of that term in Maritime geography, see there
By structure
Based on structure and material used, dams are classified as timber dams, arch-gravity dams, embankment dams or masonry dams, with several subtypes. Lumber or timber is Wood in any of its stages from felling through readiness for use as structural Material for Construction, or An arch-gravity dam, such as the Hoover Dam, is a dam with the characteristics of both an Arch dam and a Gravity dam. An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi- plastic mound of various Masonry dams are Dams made out of Masonry, and are of either the gravity or the arch type
Masonry dams
Arch dams
- See also: Geotechnical engineering
In the arch dam, stability is obtained by a combination of arch and gravity action. An arch dam is a thin curved Concrete or Masonry dam structure which is built to curve upstream so that the force of the water against it squeezes the arch Geotechnical engineering is the branch of Civil engineering concerned with the engineering behavior of earth materials If the upstream face is vertical the entire weight of the dam must be carried to the foundation by gravity, while the distribution of the normal hydrostatic pressure between vertical cantilever and arch action will depend upon the stiffness of the dam in a vertical and horizontal direction. Fluid pressure is the Pressure at some point within a Fluid, such as water or air A cantilever is a beam supported on only one end The beam carries the load to the support where it is resisted by moment and Shear stress. Stiffness is the resistance of an elastic body to Deformation by an applied Force. When the upstream face is sloped the distribution is more complicated. The normal component of the weight of the arch ring may be taken by the arch action, while the normal hydrostatic pressure will be distributed as described above. For this type of dam, firm reliable supports at the abutments (either buttress or canyon side wall) are more important. A buttress is an architectural structure built against (a counterfort) or projecting from a Wall which serves to support or reinforce the wall For the song see CANYONMID. For the band see Canyon (band. A canyon (rarely cañon) or gorge The most desirable place for an arch dam is a narrow canyon with steep side walls composed of sound rock. [10] The safety of an arch dam is dependent on the strength of the side wall abutments, hence not only should the arch be well seated on the side walls but also the character of the rock should be carefully inspected.
Two types of single-arch dams are in use, namely the constant-angle and the constant-radius dam. The constant-radius type employs the same face radius at all elevations of the dam, which means that as the channel grows narrower towards the bottom of the dam the central angle subtended by the face of the dam becomes smaller. Jones Falls Dam, in Canada, is a constant radius dam. In a constant-angle dam, also known as a variable radius dam, this subtended angle is kept a constant and the variation in distance between the abutments at various levels are taken care of by varying the radii. Constant-radius dams are much less common than constant-angle dams. Parker Dam is a constant-angle arch dam. Parker Dam is a Concrete Arch-gravity dam which spans the Colorado river, at a point 155 miles (250 km downstream of Hoover Dam
A similar type is the double-curvature or thin-shell dam. Wildhorse Dam near Mountain City, Nevada in the United States is an example of the type. This method of construction minimizes the amount of concrete necessary for construction but transmits large loads to the foundation and abutments. The appearance is similar to a single-arch dam but with a distinct vertical curvature to it as well lending it the vague appearance of a concave lens as viewed from downstream.
The multiple-arch dam consists of a number of single-arch dams with concrete buttresses as the supporting abutments. The multiple-arch dam does not require as many buttresses as the hollow gravity type, but requires good rock foundation because the buttress loads are heavy.
Gravity dams
In a gravity dam, stability is secured by making it of such a size and shape that it will resist overturning, sliding and crushing at the toe. The dam will not overturn provided that the moment around the turning point, caused by the water pressure is smaller than the moment caused by the weight of the dam. In Physics, the moment of force (often just moment, though there are other quantities of that name such as Moment of inertia) is a Pseudovector Fluid pressure is the Pressure at some point within a Fluid, such as water or air This is the case if the resultant force of water pressure and weight falls within the base of the dam. See also Vector addition A net force, F net = F 1 + F 2 + … (also known as a resultant force However, in order to prevent tensile stress at the upstream face and excessive compressive stress at the downstream face, the dam cross section is usually designed so that the resultant falls within the middle at all elevations of the cross section (the core). Stress is a measure of the average amount of Force exerted per unit Area. Compressive stress is the stress applied to materials resulting in their compaction (decrease of volume For this type of dam, impervious foundations with high bearing strength are essential.
When situated on a suitable site, a gravity dam inspires more confidence in the layman than any other type; it has mass that lends an atmosphere of permanence, stability, and safety. When built on a carefully studied foundation with stresses calculated from completely evaluated loads, the gravity dam probably represents the best developed example of the art of dam building. This is significant because the fear of flood is a strong motivator in many regions, and has resulted in gravity dams being built in some instances where an arch dam would have been more economical. A flood is an overflow of an expanse of water that submerges land a deluge
Gravity dams are classified as "solid" or "hollow. " The solid form is the more widely used of the two, though the hollow dam is frequently more economical to construct. Gravity dams can also be classified as "overflow" (spillway) and "non-overflow. " Grand Coulee Dam is a solid gravity dam and Itaipu Dam is a hollow gravity dam. Grand Coulee Dam is a Hydroelectric Gravity dam on the Columbia River in the U Itaipu ( Guarani: Itaipu, Portuguese: Itaipu, Spanish: Itaipú; itaiˈpu is a hydroelectric dam on A gravity dam can be combined with an arch dam, an arch-gravity dam, for areas with massive amounts of water flow but less material available for a purely gravity dam. An arch-gravity dam, such as the Hoover Dam, is a dam with the characteristics of both an Arch dam and a Gravity dam.
Arch-gravity dams
Embankment dams
Embankment dams are made from compacted earth, and have two main types, rock-fill and earth-fill dams. An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi- plastic mound of various Soil compaction occurs when weight of Livestock or heavy machinery compresses Soil, causing it to lose Pore space Embankment dams rely on their weight to hold back the force of water, like the gravity dams made from concrete.
Rock-fill dams
Rock-fill dams are embankments of compacted free-draining granular earth with an impervious zone. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere The earth utilized often contains a large percentage of large particles hence the term rock-fill. The impervious zone may be on the upstream face and made of masonry, concrete, plastic membrane, steel sheet piles, timber or other material. Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag The impervious zone may also be within the embankment in which case it is referred to as a core. In the instances where clay is utilized as the impervious material the dam is referred to as a composite dam. To prevent internal erosion of clay into the rock fill due to seepage forces, the core is separated using a filter. Filters are specifically graded soil designed to prevent the migration of fine grain soil particles. When suitable material is at hand, transportation is minimized leading to cost savings during construction. Rock-fill dams are resistant to damage from earthquakes. An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer However, inadequate quality control during construction can lead to poor compaction and sand in the embankment which can lead to liquefaction of the rock-fill during an earthquake. Soil liquefaction describes the behavior of loose saturated unconsolidated soils i Liquefaction potential can be reduced by keeping susceptible material from being saturated, and by providing adequate compaction during construction. An example of a rock-fill dam is New Melones Dam in California. New Melones Dam is a Dam on the Stanislaus River and forms New Melones Lake. California ( is a US state on the West Coast of the United States, along the Pacific Ocean.
Earth-fill dams
Earth-fill dams, also called earthen, rolled-earth or simply earth dams, are constructed as a simple embankment of well compacted earth. An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi- plastic mound of various An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi- plastic mound of various A homogeneous rolled-earth dam is entirely constructed of one type of material but may contain a drain layer to collect seep water. A zoned-earth dam has distinct parts or zones of dissimilar material, typically a locally plentiful shell with a watertight clay core. Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and Modern zoned-earth embankments employ filter and drain zones to collect and remove seep water and preserve the integrity of the downstream shell zone. An outdated method of zoned earth dam construction utilized a hydraulic fill to produce a watertight core. A hydraulic fill is an embankment or other fill in which the materials are deposited in place by a flowing stream of water with the deposition being selective Rolled-earth dams may also employ a watertight facing or core in the manner of a rock-fill dam. An interesting type of temporary earth dam occasionally used in high latitudes is the frozen-core dam, in which a coolant is circulated through pipes inside the dam to maintain a watertight region of permafrost within it. This article is about frozen ground For other meanings see Permafrost (disambiguation.
Because earthen dams can be constructed from materials found on-site or nearby, they can be very cost-effective in regions where the cost of producing or bringing in concrete would be prohibitive. This makes it better for the environment too.
Asphalt-Concrete Core
A third type of embankment dam is built with asphalt concrete core. Asphalt concrete, normally known simply as Asphalt, is a Composite material commonly used for construction of pavement, Highways and The majority of such dams are built with rock and/or gravel as the main fill material. Almost 100 dams of this design have now been built world-wide since the first such dam was completed in 1962. All asphalt-concrete core dams built so far have an excellent performance record. The type of asphalt used is a viscoelastic-plastic material that can adjust to the movements and deformations imposed on the embankment as a whole, and to settlements in the foundation. Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products The flexible properties of the asphalt make such dams especially suited in earthquake regions. Asphalt ( is a sticky black and highly viscous liquid or semi-solid that is present in most crude Petroleums and in some natural deposits sometimes termed asphaltum An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer
Cofferdams
A cofferdam is a (usually temporary) barrier constructed to exclude water from an area that is normally submerged. Construction A cofferdam (also called coffer) is an enclosure beneath the water constructed to allow water to be displaced by air for the purpose of creating a dry Construction A cofferdam (also called coffer) is an enclosure beneath the water constructed to allow water to be displaced by air for the purpose of creating a dry Made commonly of wood, concrete or steel sheet piling, cofferdams are used to allow construction on the foundation of permanent dams, bridges, and similar structures. Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 A foundation is a Structure that transfers loads to the earth When the project is completed, the cofferdam may be demolished or removed. See also causeway and retaining wall. In modern usage a causeway is a road or railway elevated by a bank usually across a broad Body of water or Wetland. A retaining wall is a structure that holds back Soil or rock from a Building, structure or area Common uses for cofferdams include construction and repair of off shore oil platforms. In such cases the cofferdam is fabricated from sheet steel and welded into place under water. Air is pumped into the space, displacing the water allowing a dry work environment below the surface. Upon completion the cofferdam is usually deconstructed unless the area requires continuous maintenance.
Timber dams
Timber dams were widely used in the early part of the industrial revolution and in frontier areas due to ease and speed of construction. Lumber or timber is Wood in any of its stages from felling through readiness for use as structural Material for Construction, or Rarely built in modern times by humans due to relatively short lifespan and limited height to which they can be built, timber dams must be kept constantly wet in order to maintain their water retention properties and limit deterioration by rot, similar to a barrel. The locations where timber dams are most economical to build are those where timber is plentiful, cement is costly or difficult to transport, and either a low head diversion dam is required or longevity is not an issue. In the most general sense of the word a cement is a binder a substance which sets and hardens independently and can bind other materials together Timber dams were once numerous, especially in the North American west, but most have failed, been hidden under earth embankments or been replaced with entirely new structures. Two common variations of timber dams were the crib and the plank.
Timber crib dams were erected of heavy timbers or dressed logs in the manner of a log house and the interior filled with earth or rubble. The heavy crib structure supported the dam's face and the weight of the water.
Timber plank dams were more elegant structures that employed a variety of construction methods utilizing heavy timbers to support a water retaining arrangement of planks.
Very few timber dams are still in use. Timber, in the form of sticks, branches and withes, is the basic material used by beavers, often with the addition of mud or stones. Beavers are two primarily nocturnal semi-aquatic species of Rodent, one native to North America and one to Europe
Steel dams
A steel dam is a type of dam briefly experimented with in around the turn of the 19th-20th Century which uses steel plating (at an angle) and load bearing beams as the structure. A steel dam is a type of Dam (a structure to impound or retard the flow of water that is made of Steel, rather than the more common Masonry, Earthworks Intended as permanent structures, steel dams were an (arguably failed) experiment to determine if a construction technique could be devised that was cheaper than masonry, concrete or earthworks, but sturdier than timber crib dams.
Beaver dams
Beavers create dams primarily out of mud and sticks to flood a particular habitable area. Beavers are two primarily nocturnal semi-aquatic species of Rodent, one native to North America and one to Europe By flooding a parcel of land, beavers can navigate below or near the surface and remain relatively well hidden or protected from predators. The flooded region also allows beavers access to food, especially during the winter.
Construction elements
Power generation plant
As of 2005, hydroelectric power, mostly from dams, supplies some 19% of the world's electricity, and over 63% of renewable energy. Hydroelectricity is electricity generated by Hydropower, ie the production of power through use of the gravitational force of falling water Renewable energy is Energy generated from Natural resources mdashsuch as Sunlight, Wind, Rain, tides and geothermal [11] Much of this is generated by large dams, although China uses small scale hydro generation on a wide scale and is responsible for about 50% of world use of this type of power. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National [11]
Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator; to boost the power generation capabilities of a dam, the water may be run through a large pipe called a penstock before the turbine. Potential energy can be thought of as Energy stored within a physical system A water turbine is a rotary Engine that takes energy from moving water In Electricity generation, an electrical generator is a device that converts Mechanical energy to Electrical energy, generally using Electromagnetic A penstock is a Sluice or gate or intake structure that controls water flow or an enclosed pipe that delivers water to Hydraulic turbines and A turbine is a rotary Engine that extracts Energy from a Fluid flow A variant on this simple model uses pumped storage hydroelectricity to produce electricity to match periods of high and low demand, by moving water between reservoirs at different elevations. Hydro-storage redirects here For storage of water for other purposes see Reservoir. A reservoir is most broadly a place or hollow vessel where Fluid is kept in Reserve, for later use At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine.
Spillways
A spillway is a section of a dam designed to pass water from the upstream side of a dam to the downstream side. A spillway is a structure used to provide for the controlled release of flows from a Dam or Levee into a downstream area typically being the river that was dammed Many spillways have floodgates designed to control the flow through the spillway. Floodgates are adjustable gates used to control water flow in reservoir, River, Stream, or Levee systems Types of spillway include: A service spillway or primary spillway passes normal flow. An auxiliary spillway releases flow in excess of the capacity of the service spillway. An emergency spillway is designed for extreme conditions, such as a serious malfunction of the service spillway. A fuse plug spillway is a low embankment designed to be over topped and washed away in the event of a large flood. A fuse plug is a collapsible dam installed on Spillways in Dams to increase the dam's capacity Fusegate elements are independent free-standing block set side by side on the spillway which work without any remote control. They allow to increase the normal pool of the dam without compromising the security of the dam because they are designed to be gradually evacuated for exceptional events. They work as fixed weir most of the time allowing overspilling for the common floods.
The spillway can be gradually eroded by water flow, including cavitation or turbulence of the water flowing over the spillway, leading to its failure. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Cavitation is defined as the phenomenon of formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure In Fluid dynamics, turbulence or turbulent flow is a fluid regime characterized by chaotic Stochastic property changes It was the inadequate design of the spillway which led to the 1889 over-topping of the South Fork Dam in Johnstown, Pennsylvania, resulting in the infamous Johnstown Flood (the "great flood of 1889"). The South Fork Dam was located on Lake Conemaugh an artificial body of water located near South Fork Pennsylvania. Johnstown is a city in Cambria County, Pennsylvania, United States, miles east of Pittsburgh The Commonwealth of Pennsylvania ( often colloquially referred to as PA (its abbreviation by natives and Northeasterners is a state located in the Northeastern The Johnstown Flood disaster (or Great Flood of 1889 as it became known locally occurred on May 31, 1889.
Erosion rates are often monitored, and the risk is ordinarily minimized, by shaping the downstream face of the spillway into a curve that minimizes turbulent flow, such as an ogee curve. Ogee is a shape consisting of a concave arc flowing into a convex arc so forming an S-shaped curve with vertical ends
Dam creation
Common purposes
| Function | Example |
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| Power generation | Hydroelectric power is a major source of electricity in the world. Hydroelectricity is electricity generated by Hydropower, ie the production of power through use of the gravitational force of falling water Many countries have rivers with adequate water flow, that can be dammed for power generation purposes. For example, the Itaipu on the Paraná River in South America generates 14 GW and supplied 93% of the energy consumed by Paraguay and 20% of that consumed by Brazil as of 2005. Itaipu ( Guarani: Itaipu, Portuguese: Itaipu, Spanish: Itaipú; itaiˈpu is a hydroelectric dam on This article is about the second-longest river in South America For the shorter river in Goiás, central Brazil see Paranã River The Paraná River South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. Paraguay, officially the Republic of Paraguay ( Spanish: República del Paraguay; Guaraní: Tetã Paraguái) is one of the only |utc_offset = -2 to -4 |time_zone_DST = BRST |utc_offset_DST = -2 to -5 |cctld |
| Stabilize water flow / irrigation | Dams are often used to control and stabilize water flow, often for agricultural purposes and irrigation. Agriculture refers to the production of goods through the growing of plants and fungi and the raising of domesticated Animals The study of agriculture Irrigation is an artificial application of water to the soil usually for assisting in growing crops [12] Others such as the Berg Strait dam can help to stabilize or restore the water levels of inland lakes and seas, in this case the Aral Sea. The Aral Sea ( Kazakh: Арал Теңізі Aral Tengizi, Orol dengizi Russian: Аральскοе мοре Tajik / Persian: Daryocha-i [13] |
| Flood prevention | Dams such as the Blackwater dam of Webster, New Hampshire and the Delta Works are created with flood control in mind. Webster is a town in Merrimack County, New Hampshire, United States. New Hampshire ( is a state in the New England region of the northeastern United States of America. The Deltaworks are a series of constructions built between 1950 and 1997 in the southwest of The Netherlands to protect a large area of land around the Rhine-Meuse-Scheldt [14] |
| Land reclamation | Dams (often called dykes or levees in this context) are used to prevent ingress of water to an area that would otherwise be submerged, allowing its reclamation for human use. LeveeEmbankmentDitch A dike (or dyke) levee, levée, embankment, floodbank or stopbank is a natural or artificial Dike (constructionEmbankmentA levee, levée, dike (or dyke) embankment, floodbank or stopbank is a natural or artificial Land reclamation is either of two distinct practices One involves creating new land from sea- or riverbeds the other refers to restoring an area to a more natural state (such as after |
| Water diversion | See: diversion dam. A diversion dam is the term for a Dam that diverts all or a portion of the flow of a River from its natural course |
Siting (location)
One of the best places for building a dam is a narrow part of a deep river valley; the valley sides can then act as natural walls. "Riverine" redirects here For the use of that term in Maritime geography, see there In Geology, a valley (also called a vale, dale, glen or strath and near or in Appalachia, a draw) is The primary function of the dam's structure is to fill the gap in the natural reservoir line left by the stream channel. The sites are usually those where the gap becomes a minimum for the required storage capacity. The most economical arrangement is often a composite structure such as a masonry dam flanked by earth embankments. Masonry is the building of structures from individual units laid in and bound together by mortar, and the term "masonry" can also refer to the units themselves The current use of the land to be flooded should be dispensable.
Significant other engineering and engineering geology considerations when building a dam include:
- permeability of the surrounding rock or soil
- earthquake faults
- landslides and slope stability
- peak flood flows
- reservoir silting
- environmental impacts on river fisheries, forests and wildlife (see also fish ladder)
- impacts on human habitations
- compensation for land being flooded as well as population resettlement
- removal of toxic materials and buildings from the proposed reservoir area
Impact assessment
Impact is assessed in several ways: the benefits to human society arising from the dam (agriculture, water, damage prevention and power), the harm or benefits to nature and wildlife (especially fish and rare species), the impact on the geology of an area - whether the change to water flow and levels will increase or decrease stability, and the disruption to human lives (relocation, loss of archeological or cultural matters underwater). Engineering is the Discipline and Profession of applying technical and scientific Knowledge and Engineering Geology is the application of the geologic sciences to engineering practice for the purpose of assuring that the geologic factors affecting the location design construction Permeability in the Earth sciences (commonly symbolized as κ, or k) is a measure of the ability of a material (typically a rock or unconsolidated An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer A landslide is a geological phenomenon which includes a wide range of ground movement such as rock falls deep failure of slopes and shallow debris flows which can occur The field of slope stability encompasses the analysis of static and dynamic stability of slopes of earth and rock-fill dams slopes of other types of embankments excavated slopes The environmental impacts of dams have come under renewed examination in recent years Fishways, most commonly called fish ladders but also known as fish passes and in Australia also referred to as fish steps, are structures on or around artificial An endangered species is a population of an organism which is at risk of becoming Extinct because it is either few in numbers or threatened by changing environmental or predation Archaeology, archeology, or archæology (from Greek grc ἀρχαιολογία archaiologia – grc ἀρχαῖος archaīos
Environmental impact
Dams affect many ecological aspects of a river. The environmental impacts of dams have come under renewed examination in recent years Rivers depend on the constant disturbance of a certain tolerance. Dams slow the river and this disturbance may damage or destroy this pattern of ecology. Temperature is also another problem that dams create. Rivers tend to have fairly homogeneous temperatures. Reservoirs have layered temperatures, warm on the top and cold on the bottom; in addition often it is water from the colder (lower) layer which is released downstream, and this may have a different dissolved oxygen content than before. Oxygen saturation is a relative measure of the amount of Oxygen that is Dissolved or carried in a given medium Organisms depending upon a regular cycle of temperatures may be unable to adapt; the balance of other fauna (especially plant life and microscopic fauna) may be affected by the change of oxygen content. Fauna is all of the Animal life of any particular region or time
Water exiting a turbine usually contains very little suspended sediment, which can lead to scouring of river beds and loss of riverbanks; for example, the daily cyclic flow variation caused by the Glen Canyon Dam was a contributor to sand bar erosion. Glen Canyon Dam is a Dam on the Colorado River at Page Arizona, USA operated by the United States Bureau of Reclamation. A shoal or sandbar (also called sandbank) is a somewhat Linear Landform within or extending into a body of Water, Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind
Older dams often lack a fish ladder, which keeps many fish from moving up stream to their natural breeding grounds, causing failure of breeding cycles or blocking of migration paths. Fishways, most commonly called fish ladders but also known as fish passes and in Australia also referred to as fish steps, are structures on or around artificial [15] Even the presence of a fish ladder does not always prevent a reduction in fish reaching the spawning grounds upstream. Spawning is the production or depositing of large quantities of eggs in water In some areas, young fish ("smolt") are transported downstream by barge during parts of the year. BARGE, the Big August RecGambling Excursion is a yearly convention held in Las Vegas during the first weekend of August Turbine and power-plant designs that have a lower impact upon aquatic life are an active area of research.
A large dam can cause the loss of entire ecospheres, including endangered and undiscovered species in the area, and the replacement of the original environment by a new inland lake. An endangered species is a population of an organism which is at risk of becoming Extinct because it is either few in numbers or threatened by changing environmental or predation The following is a list of Cryptids and Relicts, those animals studied under the field of Cryptozoology.
Depending upon the circumstances, a dam can either reduce or increase the net production of greenhouse gases. Greenhouse gases are gaseous constituents of the atmosphere bothnatural and anthropogenic that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared An increase can occur if the reservoir created by the dam itself acts as a source of substantial amounts of potent greenhouse gases (methane and carbon dioxide) due to plant material in flooded areas decaying in an anaerobic environment. Greenhouse gases are gaseous constituents of the atmosphere bothnatural and anthropogenic that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single For other uses of the term "hypoxia" see Hypoxia. Hypoxia or oxygen depletion is a phenomenon that occurs in aquatic environments According to the World Commission on Dams report, when the reservoir is relatively large and no prior clearing of forest in the flooded area was undertaken, greenhouse gas emissions from the reservoir could be higher than those of a conventional oil-fired thermal generation plant. [16] A decrease can occur if the dam is used in place of traditional power generation, since electricity produced from hydroelectric generation does not give rise to any flue gas emissions from fossil fuel combustion (including sulfur dioxide, nitric oxide, carbon monoxide, dust, and mercury from coal). Flue gas emissions from fossil fuel combustion refers to the Combustion product gas resulting from the burning of Fossil fuels. Nitric oxide or nitrogen monoxide is a Chemical compound with Chemical formula N[[Oxygen O]] Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum
Human social impact
The impact on human society is also significant. For example, the Three Gorges Dam on the Yangtze River in China, is more than five times the size of the Hoover Dam (U.S.) and will create a reservoir 600 km long, to be used for hydro-power generation. Zh-yue三峽大壩 The Three Gorges Dam ( is a hydroelectric River Dam that spans the Yangtze River in Sandouping, China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Hoover Dam, also sometimes known as Boulder Dam, is a Concrete Arch-gravity dam in the Black Canyon of the Colorado River, on the The United States of America —commonly referred to as the Its construction required the loss of over a million people's homes and their mass relocation, the loss of many valuable archaeological and cultural sites, as well as significant ecological change. [17]
Economics
Construction of a hydroelectric plant requires a long lead-time for site studies, hydrological studies, and environmental impact assessment, and are large scale projects by comparison to traditional power generation based upon fossil fuels. Fossil fuels or mineral fuels are fossil source Fuels that is Hydrocarbons found within the top layer of the Earth’s crust. The number of sites that can be economically developed for hydroelectric production is limited; new sites tend to be far from population centers and usually require extensive power transmission lines. Power transmission is the movement of Energy from its place of generation to a location where it is applied to performing useful work. Hydroelectric generation can be vulnerable to major changes in the climate, including variation of rainfall, ground and surface water levels, and glacial melt, causing additional expenditure for the extra capacity to ensure sufficient power is available in low water years. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of A spirit level or bubble level is an instrument designed to indicate whether a surface is Level or Plumb.
Once completed, if it is well designed and maintained, a hydroelectric power source is usually comparatively cheap and reliable. It has no fuel and low escape risk, and as a renewable energy source it is cheaper than both nuclear and wind power. Renewable energy is Energy generated from Natural resources mdashsuch as Sunlight, Wind, Rain, tides and geothermal It is more easily regulated to store water as needed and generate high power levels on demand, compared to wind power. Wind Power is the conversion of wind energy into a useful form such as electricity using Wind turbines At the end of 2007 worldwide capacity of wind-powered generators was
Dam failure
Dam failures are generally catastrophic if the structure is breached or significantly damaged. Routine deformation monitoring of seepage from drains in, and around, larger dams is necessary to anticipate any problems and permit remedial action to be taken before structural failure occurs. Deformation monitoring (also referred to as Deformation survey) is the systematic measurement and tracking of the alteration in the shape or dimensions of an object as a result Most dams incorporate mechanisms to permit the reservoir to be lowered or even drained in the event of such problems. Another solution can be rock grouting - pressure pumping portland cement slurry into weak fractured rock. Grout is a Construction material used to embed Rebars in Masonry walls connect sections of pre-cast Concrete, fill voids and seal joints (like Portland cement is the most common type of Cement in general usage in many parts of the world as it is a basic ingredient of Concrete, mortar, Stucco
During an armed conflict, a dam is to be considered as an "installation containing dangerous forces" due to the massive impact of a possible destruction on the civilian population and the environment. As such, it is protected by the rules of International Humanitarian Law (IHL) and shall not be made the object of attack if that may cause severe losses among the civilian population. International humanitarian law ( IHL) often referred to as the Laws of war, the laws and customs of war or the law of armed conflict To facilitate the identification, a protective sign consisting of three bright orange circles placed on the same axis is defined by the rules of IHL. Protective signs are symbols to be used during an armed conflict to mark persons and objects under the protection of various treaties of International Humanitarian Law
The main causes of dam failure include spillway design error (South Fork Dam), geological instability caused by changes to water levels during filling or poor surveying (Vajont Dam, Malpasset), poor maintenance, especially of outlet pipes (Lawn Lake Dam, Val di Stava Dam collapse), extreme rainfall (Shakidor Dam), and human, computer or design error (Buffalo Creek Flood, Dale Dike Reservoir, Taum Sauk pumped storage plant). The South Fork Dam was located on Lake Conemaugh an artificial body of water located near South Fork Pennsylvania. Vajont Dam is a Dam completed in 1961 under Monte Toc, 100 km north of Venice, Italy. Malpasset was an arch dam on the Reyran River constructed approximately 7 km north of Fréjus on the Côte d'Azur, southern France Lawn Lake Dam was an earthen Dam in Rocky Mountain National Park that failed on July 15, 1982 at about 6 a The Val di Stava Dam collapse occurred on July 19, 1985 when a Tailings Dam above the village of Stava near Tesero, northern The Shakidor (Shadi Kor Dam is located near Pasni, in the Balochistan province of southwest Pakistan, 1900 km (1180 miles from Islamabad The Buffalo Creek Flood was an incident that occurred on February 26, 1972 when a Coal Slurry impoundment Dam #3 on a hillside Dale Dike Reservoir or Dale Dyke Reservoir ( famous for causing the Great Sheffield Flood, is in the north-east Peak District, in South The remains of the Taum Sauk pumped storage plant are located in the St
A notable case of deliberate dam failure (prior to the above ruling) was the British Royal Air Force Dambusters raid on Germany in World War II (codenamed "Operation Chastise"), in which three German dams were selected to be breached in order to have an impact on German infrastructure and manufacturing and power capabilities deriving from the Ruhr and Eder rivers. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Operation Chastise was the official name for the attacks on German Dams on 17 May 1943 in the Second World War using a specially developed " The Ruhr is a medium-size River in western Germany ( North Rhine-Westphalia) a right tributary (east-side of the Rhine. The Eder is a 177 km long River in Germany, left tributary of the Fulda River. This raid later became the basis for several films.
- Further information: List of dam failures
Notes
- ^ Guinness Book of Records 1997 Pages 108-109 ISBN 0-85112-693-6
- ^ The American Heritage® Dictionary of the English Language, Fourth Edition
- ^ Source: Tijdschrift voor Nederlandse Taal- en Letterkunde (Magazine for Dutch Language and Literature), 1947. A Dam is a barrier across flowing water that obstructs directs or slows down the flow often creating a reservoir, Lake or impoundments The first known appearance of the word dam stems from 1165. However, there is one village, Obdam, that is already mentioned in 1120. The word seems to be related to the Greek word taphos, meaning grave or grave hill. So the word should be understood as dike from dug out earth. The names of more than 40 places (with minor changes) from the Middle Dutch era (1150 - 1500 CE) such as Amsterdam (founded as 'Amstelredam' in the late 12th Century) and Rotterdam, also bear testimony to the use of the word in Middle Dutch at that time. Amsterdam (pronounced) is the capital and largest city of the Netherlands, located in the province of North Holland in the west Rotterdam (pronounced) is the 2nd-largest City by population in the Netherlands, located in the province of
- ^ According to Joseph Needham. Noel Joseph Terence Montgomery Needham, CH, FRS, FBA ( December 9, 1900 – March 24 1995) was a British
- ^ Science and Civilization in China, Joseph Needham, 1946, page 368, http://books.google.com/books?id=l6TVhvYLaEwC&pg=RA1-PA138&lpg=RA1-PA138&dq=needham+ceylon&source=web&ots=m_8OpjaZdL&sig=2Ir6nKuKbFqXJe9Z1lSiDlJW5Rk#PRA2-PA368,M1
- ^ a b Mohamed Bazza (28-30). overview of the hystory of water resources and irrigation management in the near east region (english). Retrieved on 2007-08-01. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 30 BC - Octavian (later known as Augustus enters Alexandria, Egypt, bringing it under the control of the Roman
- ^ a b Wiebe, Bijker (2007). "Dikes and Dams, Thick with Politics". Isis 98: 109-123.
- ^ Needham, Joseph (1986). Science and Civilization in China: Volume 4, Part 3. Taipei: Caves Books, Ltd.
- ^ Methodology and Technical Notes (HTML) (English). Watersheds of the World. Retrieved on 2007-08-01. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 30 BC - Octavian (later known as Augustus enters Alexandria, Egypt, bringing it under the control of the Roman “A large dam is defined by the industry as one higher than 15 meters high and a major dam as higher than 150. 5 meters. ”
- ^ Arch Dam Forces. Retrieved on 2007-01-07. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1325 - Alfonso IV becomes King of Portugal. 1558 - France takes Calais, the last continental
- ^ a b Renewables Global Status Report 2006 Update, REN21, published 2006, accessed 2007-05-16
- ^ The Impact of Agricultural Development on Aquatic Systems and its Effect on the Epidemiology of Schistosomes in Rhodesia (PDF) (English). REN21, the R enewable E nergy Policy N etwork for the 21 st Century, is a policy network that provides a forum for international leadership IUCN. “Recently, agricultural development has concentrated on soil and water conservation and resulted in the construction of a multitude of dams of various capacities which tend to stabilize water flow in rivers and provide a significant amount of permanent and stable bodies of water. ”
- ^ Kazakhstan (HTML) (English). Land and Water Development Division (1998). Retrieved on 2007-08-01. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 30 BC - Octavian (later known as Augustus enters Alexandria, Egypt, bringing it under the control of the Roman “construction of a dam (Berg Strait) to stabilize and increase the level of the northern part of the Aral Sea. ”
- ^ Blackwater Dam (HTML) (English). US Army Corps of Engineers. “The principal objective of the dam and reservoir is to protect downstream communities”
- ^ Dam Fact Sheet
- ^ Hydroelectric power's dirty secret revealed - earth - 24 February 2005 - New Scientist
- ^ "Three Gorges dam wall completed", china-embassy, 20 May 2006. Events 325 - The First Council of Nicaea &ndash the first Ecumenical Council of the Christian Church is held Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Retrieved on 2006-05-21. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 878 - Syracuse Italy is captured by the Muslim sultan of Sicily.
See also
- Beaver a dam-building rodent
- Delta Works
- Canal lock
- List of reservoirs and dams
- List of world's tallest dams
- Dam Busters
- Zuiderzee works
External links
- International Commission on Large Dams (ICOLD)
- Structurae: Dams and Retaining Structures
- The World's Largest Dams
- Dams on Planete-TP
- "Design of Small Dams", US Bureau of Reclamation, 65MB pdf
- "Dam science" Canadian Geographic
- International Rivers
- Dam Research
- asphaltcoredams.com
- University of Washington Freshwater and Marine Image Bank Collection
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