The dam is ... The dams on the rivers. Earth Dam

A dam is a structure that helps to block the rise of water or its flow for various purposes. The very first buildings of this type were discovered in Egypt, where they were used to create water storage facilities. Such an object archaeologists from Germany found in two hundred kilometers from Cairo. It was a dam with its own name "Sad-el-Karaf", which occurs in the records of Herodotus. As for her age, experts disagree. Some believe that it was built in 3200 BC, others believe that in the interval between 2950-2750. BC.

What was the oldest dam made of?

What size was the oldest dam? This impressive structure was a double stone wall, between which the sides were additionally sketched fragments of stones. The length of the dam was over the ridge over 100 meters, the height reached 12 meters. Such a project allowed the accumulation of up to two million cubic meters of water in Wadi al-Garawi.

The Chinese built scale and for centuries

Some historians believe that the dams in the Bronze Age were built everywhere in the points of development of a particular local civilization. For example, in Mesopotamia found a stone structure, dating from the seventh century BC. In ancient Syria, similar structures were built 1,500 years before Christ. (Nahr el-Assi). Large-scale construction of dams was also observed in ancient China. Here the master became famous, and later the Emperor Yu, who in 2283 BC the acting ruler entrusted the management of all water construction in the empire. Under the leadership of Great Yui (as it is still called), not one dam was erected. This was a large-scale construction for centuries and millennia, which allowed, for example, 50,000 square kilometers in the Sichuan Desert, at the expense of the waters of the Minjiang River, to be irrigated by 250 BC. And it was in China that a practice was born to build hydraulic structures using an element such as an arch.

They were designed by da Vinci himself

In Europe, where the problem of irrigation was not as acute as in Asia and Africa, dams appeared much later - in the 16th century. Arched variants, in particular, are mentioned in the Spanish chronicles in 1586, but engineers believe that the devices themselves could be built centuries earlier. This is based on the fact that the geniuses of that time - Leonado da Vinci, Malatesta, Mechini - participated in their designing, and also taking into account the accumulated experience that came to Europe after contacts with the Arab world. For example, it is known that even such a seemingly not very solid structure, like an earth dam, was exploited for a century before it collapsed (it was erected in France in 1196).

The use of dams in Russia

For Russia, with its rich water resources, also, at first glance, the dam was not particularly required. However, they existed here since the 14th century of our era and were used in watermill systems . The first mention of the dams was noted in the testament of Dmitry Donskoy, attributed to 1389. Particular interest in such facilities was shown by Peter the First, therefore in the 18th century there were already more than 200 objects in the Russian Empire, among which a high earth dam - Zmeinogorskaya - stood out. Water resources through such devices were transferred for use in textile, mining and other enterprises of that time.

A dam is a hydraulic structure that can relate to a particular kind of objects, depending on the classification. Today, allocate reservoir, water-lifting and lifting equipment. Reservoir dams are usually very high and have the ability to regulate the discharge of water. Low-rise buildings (for example, for the construction of ponds) usually do not have runoff. Another important classification is the subdivision of objects, depending on the depth of the water before the clamping. Here, low-, medium- and high-pressure dams are distinguished (up to 15, 50 and over 50 meters, respectively).

Dams for rivers and ravines

The dams on the rivers can be erected transversely (to raise the water level, arrange a waterfall, the force of which can somehow be used, to make the shallow part of the river passable for ships) and along (to protect against floods). In some cases, dams are blocked by streams, ravines, hollows - to keep melted snow water in them, which are then used for irrigation or for feeding the navigable canals.

The main elements of the HPP

The structure of hydraulic structures usually includes a dam, a reservoir before or after it, a water-lifting facility, a complex of hydroelectric power stations, descents for fish passage, water drains (if the system is culvert), structures to shore up and clean the system of sediment. Large objects are made of reinforced concrete, small ones can be built from soil, metal, concrete, wood or even fabric. It is known that during the flooding in Komsomolsk-on-Amur, the protective dam consisted of soldiers of the Ministry of Emergency Situations, who were holding film sheets that did not allow water to overflow over the tops of the available protective structures.

How can the dams take a load?

Another classification of dams reflects how these objects resist loads. Gravity buildings perceive impacts with their entire mass and resist due to the adhesion of the base of the dam and the base on which it stands. Such options are usually very massive. For example, the hydroelectric dam on the Indus River (Tarbela Dam) is about 143 meters high, and its length is more than 2.7 km, which creates a total volume of 130 million cubic meters. Meters. Arched objects transmit pressure to the shore. If the arch is wide and the pressure is high, then arch-gravity models or arches with buttresses in the base are used. Buttress-like versions have a thinner wall of the dam, but a reinforced base due to the sub-elements. Today the dams are being built by a bulk or in-line method, and also by the directed explosion method.

Consequences of accidents

Accidents at the dams carry substantial material losses, as not only unique equipment is destroyed, but also enterprises that work on electricity and water supplies from this dam are stopped. Water flows wash entire settlements, sometimes sowing areas are flooded, the crop is lost. But the worst thing is that dozens, hundreds and even thousands of people can die almost instantaneously.

So, in March 1928 in the canyon of San Francisco destroyed the dam of St. Francis, then killed about six hundred people, and many meters of the dam itself was found about a kilometer away from the breakthrough. In the USSR during the Great Patriotic War (1941) it was decided to deliberately blow up the Dnieper Hydroelectric Dam in connection with the occupation of Zaporozhye by fascist troops. A massive structure of concrete was partially damaged by 20 tons of ammonal. How many people died then, is still not exactly defined. The figures are from twenty to one hundred thousand people, including troops, refugees and the population, which could be on the left bank of the Dnieper, which took the main blow of the water element.

The total number of victims - about 230 thousand people

Post-war accidents at the dams of large power plants led to even larger victims. In August 1975, when the Banciao Dam broke through, only 26,000 people were drowned, and in view of the spread of epidemics and famine, the number of deaths reached 170-230 thousand people. At the same time, about a third of the head of livestock were destroyed and about 6 million buildings and buildings were destroyed. The highway from Guangzhou to Beijing was closed for eighteen days. And all this happened because the dams, designed for maximum rainfall, could not withstand the onslaught of water masses, which brought the typhoon "Nina". On August 8, 1975, the smallest of the dams collapsed, which led to the dumping of water in Bantsao, where 62 dams were breached in a short time. The resulting wave was a width of up to 10 km and a height of three to seven meters. Some Chinese villages were completely washed away with their inhabitants.

To prevent the dam from breaking, a number of measures are being taken today, including observance of dam design parameters, verification of compliance during operations, observation during operation, collection of visual and geodetic information, etc. For dams, two inconsistencies to the requirements of projects and standards are distinguished: "К1 "- the object has a potentially dangerous condition and urgent measures are needed to eliminate its causes, and" K2 "means a pre-emergency condition, possibly destruction, rescue-evacuation operations are needed.