Tourists watch water gushing out from the Xiaolangdi Reservoir during a sand-washing operation in Luoyang, central China's Henan Province, July 5, 2013. The on-going operation, conducted on Friday, works by discharging water at a volume of 2,600 cubic meters per second from the reservoir in order to clear up the sediment in the Yellow River, the country's second-longest waterway. The river had been plagued by an increasing amount of mud and sand. Each year, the river bed rises as silt deposits build up, slowing down the water flow in the lower reaches.