actual shooting of UAV! Change in the water! The door to a new world has been opened! Space-time warp! Underwater black hole!

well, only the first five words above are true.

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what exactly is this video of a drone overlooking a big hole in the water? It's actually the spillway of the dam. The function of the spillway is to adjust the water storage capacity and remove too much water, which can ensure the safety of the dam.

spillways have many different structural designs, and the type that is most likely to attract attention on the Internet is the bell type, or Bell-mouth spillway type.

when the water level is not high, they look like this:

the structure and principle diagram is as follows:

but when the flood strikes and the water level rises, the painting style of these spillway devices will suddenly change and open the door to a new world.

(look at it and get sucked in! )

reference:

https://en.wikipedia.org/wiki/Spillway

http://sploid.gizmodo.com/drone-footage-of-a-draining-dam-looks-like-flying-into-1792622962