WUHAN, Sept. 11 (Xinhua) -- China's Three Gorges Reservoir launched this year's tentative impoundment on Tuesday to store water at the target 175 meters above sea level.

The impounding work started from an initial level of 146.73 meters, needing about 21.3 billion cubic meters of water to reach the target, according to the Changjiang Water Resources Commission of the Ministry of Water Resources.

This year's water storage of the Three Gorges Reservoir will be challenging due to less water inflow, large demand from reservoirs in the valley, as well as low water level in the middle and lower reaches of the Yangtze River, the commission said.

The Three Gorges Reservoir has carried out 11 such impounding trials since 2008 and has achieved the 175-meter target for nine consecutive years.