dam - a structure that helps to block the rise of water or over in those or other purposes.The earliest buildings of this type have been found in Egypt, where he used to create the storage of water.Such an object is found, archaeologists from Germany, two hundred kilometers from Cairo.It was a dam with his own name "Garden of El Carafa", which appears in the book of Herodotus.Regarding her age, experts disagree.Some believe that it was built in 3200 BC, others - that between 2950-2750 years.BC.
What was done oldest dam?
How big was the oldest dam?This imposing building is a double stone wall, between the parties which have been sketched by an additional stone fragments.The length of the crest of the dam was more than 100 meters, the height is up to 12 meters.Such a project allowed to accumulate up to two million cubic meters of water in Wadi el-Gharavi.
The Chinese have built a large scale and for centuries
Some historians believe that the dams were built in the Bronze Age spots throughout the development of a local civilization.For example, in Mesopotamia found stone building dating back to the seventh century BC.In ancient Syria also built similar structures and a half thousand years before Christ.(Nahr al-Assi).Large-scale construction of dams was observed in ancient China.Here the famous master, and later Emperor Yu, who in 2283 BC acting ruler ordered all water management in the construction of the Empire.Under the leadership of the Great Yu (as it is still styled) was erected not one dam.It was a large-scale construction in the century and millennium, which allowed for the year 250 BC to water, for example, 50,000 square kilometers in the desert by Sichuan Minjiang River water.And this practice originated in China to build a waterworks with this element as the arch.
They designed the Da Vinci himself
In Europe, where the problem of irrigation was not as prevalent as in Asia and Africa, dams were much later - in the 16th century.Arched options, in particular, mentioned in the chronicles of the Spanish in 1586, but engineers believe that the devices themselves could be built in the century before.It is based on the fact that they participated in the design geniuses of the time - Leonado da Vinci, Malatesta, Mechin, as well as the accumulated experience that came to Europe after the contacts with the Arab world.For example, we know that even such seemingly not very durable construction as an earthen dam, used for a century before collapsed (it was built in France in 1196).
use dams in Russia
for Russia with its rich water resources and, at first glance, not much needed dams.Here, however, they have existed since the 14th century AD and used in the systems of water mills.The first mention of the dams mentioned in the testament of Dmitry Donskoy attributable to 1389.Of particular interest in these structures showed Peter the Great, so in the 18th century, the Russian Empire had more than 200 objects, among which the highest earth dam - Zmeinogorskaya.Water resources are transferred through such devices for use in the textile, mining and other enterprises of the time.
Dam - a hydraulic structure, which may relate to a particular type of objects, depending on the classification.Today, the device is isolated from reservoirs, vodoopuskayuschie and lifting.Storage dams are usually very high and have the ability to regulate water discharge.Low same structures (for example, for the ponds) flow usually do not have.Another important classification is the division of objects depending on the depth of water before zaplotom.It is isolated low-, medium- and high-pressure dam (15, 50 and 50 meters, respectively).
dam rivers and ravines
dams on the rivers can be constructed as a cross (to raise the water level, everything falls, the force which can somehow use, in order to make a shallow part of the river navigable for ships), and along(flood protection).In some cases, dams block the streams, ravines, hollows - to keep them melted snow water, which are then used for irrigation or to recharge the shipping channels.
Key elements of HPP
The structure of hydraulic structures usually include a dam, reservoir before or after it, the installation of water lift, a complex of hydroelectric power plants, hills for passage of fish, drain the water (if the system Culvert) facilities for bank stabilization and purification systemsfrom the sediment.Large objects are made of reinforced concrete, the minor can be built from the ground, metal, concrete, wood, or even fabric.It is known that during the floods in Komsomolsk-on-Amur protective dam consisted of soldiers MOE, keep on the web of film itself, which did not allow the water perehlestnut across the tops of existing protective structures.
as dams can take the load?
Another classification of dams reflects how these objects withstand stress.Gravitational built perceive beats all its weight and resist by coupling the soles of the dam and the grounds upon which it stands.These options are usually very massive.For example, a dam on the Indus River (Tarbela Dam) has a height of about 143 meters, and the length - more than 2.7 km, which makes the total of 130 million cubic meters.meters.Arched objects transmit pressure on the shore.If the arch is wide and great pressure, then the arch-gravity models or arches with buttresses at the base.Buttress the options have a thin wall of the dam, but the base strengthened by podporochnyh elements.The dam is being built today, or alluvial bulk method, and the method of directed explosion.
consequences of accidents
accidents at dams carry with them substantial financial losses, since it destroys not only the unique equipment, and stop companies that run on electricity and supply water to this dam.Water flows sometimes washed away entire villages, flooded acreage, the crop is lost.But the worst thing that can almost instantly killed dozens, hundreds and even thousands of people.
So, in March 1928 in the canyon San Frantsiskito was the destruction of the dam of Saint Francis, then died about six hundred people, and multimeter pieces of the dam is located about a kilometer from the place of a breakthrough.In the USSR in the Great Patriotic War (1941) it was decided deliberately undermining the dam Dneproges in connection with the occupation of Zaporozhye fascist troops.The massive concrete structure was partially damaged by a 20 tons ammonal.How many people died while still not precisely defined.Call the numbers from twenty to one hundred thousand people, including troops, refugees and population, which could be on the left bank, who took the brunt of the water element.
total number of victims - about 230 thousand people
postwar accident at large hydropower dams have caused even bigger victim.In August 1975, the breakout Banqiao Dam drowned just turned 26 thousand people, and taking into account the mature epidemics and starvation death toll has reached 170-230 thousand people.Then it was destroyed about a third of a million head of livestock and destroyed nearly 6 million houses and buildings.For eighteen days it was closed highway from Guangzhou to Beijing.And all this happened because of the dam, designed for the maximum number of rainfall, did not survive the onslaught of water masses that brought typhoon "Nina."August 8, 1975 collapsed the smallest of the dams, which resulted in the discharge of water Bantsao, where for a short time were broken dam 62.The resulting wave has a width of 10 km and a height of three to seven meters.Some Chinese villages were completely washed away, along with their inhabitants.
To prevent a breakthrough dam, today taken a number of measures, among them - the observance of the parameters of the design of the dam, checking for compliance during work, supervision during the operation, collecting visual and survey information, and others. For dams are two non-compliance projectsstandards "K1" - the object is a potentially dangerous condition and need urgent measures to address its causes, and "K2" - pre-emergency state may be destroyed, need rescue and recovery work.
