Hydropower & reservoir management   Hydroelectric power - based on running water turning turbines - is the single largest contributor to the world's production of green energy.   A Chinese man fishes as water flows through water diversion holes of the Three Gorges Dam on the Yangtze River in central China's Hubei Province Wednesday, June 11, 2003. Some 10 water diversion holes were opened to release water. The water level of the Three Gorges Reservoir reached 135 meters (433 feet) on June 10. (AP Photo/Xinhua, Du Huaju) Last update: 12 July 2004