Water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)

Tourists watch as water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)

A rainbow arches across the reservoir as water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)

Water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)

Tourists watch as water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)

Water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)

A tourist takes photos as water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)

A rainbow arches across the reservoir as water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)

Tourists watch as water gushes out from Liujiaxia Hydropower Station on the Yellow River during a flood peak adjustment operation in Yongjing County, northwest China's Gansu Province, Aug. 1, 2012. (Xinhua/Shi Youdong)