Thankfully that waterway has a bridge so it doesn't have to get wet crossing the river!
I see your water bridge, but ask, what happens when a big boat wants to get past? I'll tell you what happens- The Barton Swing Aqueduct.
Amazing.
Here's a fun fact action lab pointed out: setting aside wind, etc, the load the bridge has to be designed for is only the water that fills it.
That bridge will have the same force on it from a tanker or a kyaker.
Because boats and ships displace the heavier water?
Boat displacement is the amount of water the boat displaces while floating. It is equal to boat weight.
So, if you put a 100 ton boat in enclosed bowl, you will of course get 100 tons more on a scale. However, if you do the same with a large surface body of water (river, lake, ocean), the water will be displaced equally over a large surface area, thus distributing the weight. You still get 100 tons more, but less over the are "under" the boat.
In the documentary Canal Boat Diaries the dude goes over several of these, each time i was like phhhrrrrfuckwhat
The aquaduct at Llangollen is particularly alarming to be on
Thankfully that waterway has a bridge so it doesn't have to get wet crossing the river!