How cold does it have to be to freeze a waterfall

I have designed a group of medieval towns located on a valley, all of them connected by a navigable river wich ends on a big waterfall. There are some elevators at the side of the waterfall that connect two ports, one on the top and one on the bottom. The port on the bottom is the only one who could be access by ships from out of the valley while the one on the top recives ships from the valley.

I want to freeze the waterfall and part of the coast during the winter. I understand this is very possible. So my doubts are:

• How cold does it have to be to freeze the waterfall?
• If the waterfall is frozen, must the river been frozen too?
• If everything is frozen, were are they going get water?
• If everything is frozen, is it possible to use the river like a highway for sleds

I was thinking on a 25-40 meters river widht and a waterfall of 50 meters high

I have some ideas about it, and I am researching for examples on real world, but I would like to know what you think about it.

posted over 4 years ago

Erick Silva‭

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