With a vast territory， China is rich in water resources. However， the spatial and temporal distribution of water resources is uneven due to the integrated impacts of climate， topography， and other factors. Specifically， precipitation decreases from south to north. The interannual variation of yearly precipitation is significant. Frequent floods and droughts occurred and observed. Since 1949， many conservation and hydropower engineering project， eg. ， water storage， diversion， and transfer projects have been constructed， which greatly contribut to the economic and social development. Currently， higher requirements have been put forward for water conservancy projects to support a sustainable，rapid socio-economic development， as well as the strategic needs of building a moderately prosperous society in an all-round way. In 2014， the State Council arranged 172 major water conservancy projects for water saving and water supply， providing new opportunities for water conservancy construction.
　　China is rich in hydraulic China is the world's largest producer of hydroelectricity. In the mainland， the potential annual hydroelectric power is 6.08 trillion kW . h， the average power is 694 million kW; technical developable installed capacity is 542 million kW， annual power generation is 2. 47 trillion kW·h;economically developable installed capacity is 402 million kW， annual power generation is 1.75 trillion kW·h.Presently in China， the installed capacity of hydropower is over 230 million kW， ranking first in the world. Hydropower，as a renewable clean energy， has the characteristics of mature technology， low cost，flexible operation and so on. Most countries in the world give priorities to hydropower development in energy construction. Meanwhile， China leads the world in renewable-energy production mainly from hydropower. Hydropower has made significant contributions in many aspects， For example， it helps to adjust the energy and power structure， reduce greenhouse gas emission， miti gate the climate and environment， and socio-economic development. There-fore， hydropower is listed in the key areas of energy development and renewable energy development in China.