An ancillary dam for the Three Gorges Dam, running more or less along the southern (right) bank of the Yangtze. Presumably it's meant to prevent the raised river water from flooding some section of  Maoping Zhen (the county seat of Zigui County, Hubei), or maybe just flowing out into the below-dam Yangtze along a different route. The photo is taken looking downstream from Maoping's riverside park; the main Three Gorges Dam can be seen through the fog in the background on the left,
User:Vmenkov
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<span class="int-own-work">Self-photographed</span>