The Hukou Waterfalls on the Yellow River at the border of north and northwest China's Shanxi and Shaanxi provinces has long been known for its high concentration of sand, probably the highest in the world. 

But from May to June every year, clear water is seen at the waterfalls as a result of sand settlement there because of slower water flow, at a rate of about 300 cubic meters per second.

(All images via VCG)

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