Reservoir construction is closely related to hydro—power development

Hydro-energy refers to the energy reserved in the river and ocean waters， existing in the water in the form of static energy， pressure energy and kinetic energy， also known as water resources. In the general sense， water resources includes river hydro-energy， tidal hydro-energy， wave energy， ocean energy and other resources； narrowly speaking， river hydro-energy resource refers to water resources. Reservoir construction is not only a way of water resources development， but the necessary part of hydro-energy development as well. Therefore， hydro-energy development and water resources development are complementing and mutually promoting each other

China posses abundant hydro-energy resource， ranking first in the world in terms of the total amount. But the spatial and temporal distribution of hydro-energy resource is uneven. Because of the uneven distribution of time， to adjust the amount by building reservoir is often needed； As to the uneven geographical distribution， a stable and efficient power grid is required to achieve long-distance delivery of hydro-energy from "west to east ." The hydro-energy resource in our country is concentrately distributed in the upper reaches of Jinsha River， Yalong River， Dadu River， Lancang River， Wujiang River and Yangtze River as well as the mainstream of major rivers， such as Nujiang River， which makes it easy for centralized development.

Energy produced by hydro-power is clean and renewable

Hydro-power refers to the static energy reserved in the river and ocean waters. To convert hydro-energy to electrical energy， we need to build different types of hydro-power stations which is the engineering facilities composed of a series of buildings and equipments. The building is mainly used to concentrate the water falling from higher natural flow and form the head of water， and then collect and regulate the amount of them using the reservoir； when the water flow enters the hydro-turbine with the guidance of specific building in hydro-power station， hydro-turbine rotates pushed by water flow， thus converting hydro-energy into mechanical energy； electricity is made available by generator which is driven by hydro-turbine， through which mechanical energy is converted to electrical energy. Then through substation， power transmission and distribution equipment， electrical energy turns to electricity which is then sent to the user.

Hydro-power does not consume fuel in the operation， the management fees and the generating cost are more lower than coal-fired power as well. There is no chemical change occurred in the process of hydro-power which converts hydro-energy to electrical energy， thus no harmful substance is released which has less impact on the environment. Therefore the energy produced by hydropower is a kind of clean energy. Besides， because the energy required by hydropower is obtained from the continuous cycles of atmosphere and water of the Earth， it is also a kind of renewable energy.

The maintenance of large reservoirs is often inseparable from the construction of hydro-power stations

High dams and large reservoirs have strong storage capacity， so the water level is deep and amount of water is immense. The drainage and discharge of water in large reservoirs will produce huge amounts of energy. Necessary measures for energy dissipation are usually required， otherwise it will pose a huge threat to the safety of the dam and reservoir. But hydro-power converts hydro-energy to electrical energy which consists the most effective way of energy dissipation and also the best way to solve the threat made to dam when a large reservoir discharges water.

In flood season， the discharge of flood poses a huge challenge to the hydro-power station and dam. The dissipation structure and efficiency of the facilities have long been an important subject for hydro-power research. If the hydro-energy can not be made use of to generate electricity， while we rely on certain energy dissipation structure to dissipate energy， in the long run， the safety of almost all large reservoirs is difficult to be guaranteed. Therefore， the probability of accidents happened to dams with hydro-power station is greatly reduced than non-profit dams without hydro-power station. According to statistics， a variety of collapse accidents occurred in the world， and among them， more than 95 % accidents took place in dams without hydro-power station. Overall， developing hydro-energy through hydro-power often makes the dams safer.