Reservoirs refer to artificial lakes, and smaller ones are called ponds, ponds and reservoirs. The general formation method is to dam the middle and upper reaches of the river, and the river will flood the valley to form a reservoir. However, some reservoirs are built at sea, such as Plover Cove Freshwater Lake in Hong Kong. Dams are usually built in narrow valleys, because the slopes on both sides can be used as natural walls of reservoirs, and the length of dams can be greatly shortened. Before construction, it is necessary to move the houses and historic sites in the flooded area to other places.
1 Basic introduction
Note: When the total storage capacity is less than 6,543,800 cubic meters, it is called a pond dam. Total storage capacity refers to the reservoir volume below the flood level. Check flood level refers to the highest water level in front of the dam when the reservoir encounters check flood.
The famous reservoirs in China are: Three Gorges Reservoir (the world's largest water conservancy project, the Three Gorges Dam, formed by intercepting the Yangtze River), Danjiangkou Reservoir (the water source of the Middle Route of South-to-North Water Transfer Project, the largest artificial lake in Asia), Xin 'anjiang Reservoir (Qiandao Lake in Chun 'an, Hangzhou, Zhejiang, a national 5A scenic spot), Wang Ying Reservoir (Yangxin Xiandao Lake in Huangshi, Hubei, a national 4A scenic spot) and Miyun Reservoir (the largest in North China).
Two large pieces
There are three main parts of the reservoir: dam, spillway and drainage structure.
Three main functions
Flood control function of reservoir
Reservoir is one of the engineering measures widely used in flood control in China. A comprehensive reservoir with flood storage capacity should be built at an appropriate position in the upstream of the flood control area, and the flood storage capacity of the reservoir should be used to reduce the flood peak flow into the downstream river, so as to achieve the purpose of reducing flood disasters. There are two different ways for reservoir to regulate flood, one is flood detention and the other is flood storage.
(1) flood detention
Flood detention is to let the flood temporarily stay in the reservoir. When there is no gate control on the spillway of the reservoir and the water level of the reservoir is flush with the elevation of the spillway crest, the reservoir can only play the role of temporary flood interception.
(2) Flood storage function
In the case of spillway without sluice gate, in the stage of reservoir management and operation, if the reservoir water level can be reduced to the reservoir flood limit level before flood season, and the reservoir flood limit level is lower than the spillway crest elevation, the storage capacity between the flood limit level and the spillway crest elevation can play a role in flood storage. Part of the flood stored in the reservoir can play a planned role in the dry season.
When the spillway is equipped with gates, the reservoir can play a greater role in flood storage, and the reservoir can adjust the flow by changing the opening of the gates. Because of the gate control, the flood control limit water level of this kind of reservoir can be higher than the spillway crest, and the gate opening can be adjusted at any time to control the flow during flood discharge, which has dual functions of flood detention and storage.