From experience with this kind of thing when I was a teenager, all the incidents I knew of where people died involved poor planning and/or misunderstanding how to swim across a flooded river. It was always quite doable if you planned your entry, exit and backup exit points correctly, taking into consideration the water level and flow rate.

The most common way people would die was attempting to swim directly across a flooded river and exit opposite where they entered. It’s basically impossible, and people would get exhausted and drown. The second most common was to not plan an exit point. You need a place where the flow rate close to the bank at flood level is low enough that you can stop yourself and get out, and not get slammed into something and knocked unconscious and down. Also, you don’t want to do it anywhere there are submerged objects there’s a chance of getting snagged on.

Swimming in flooded rivers needs to be treated as an extreme sport. You need to be fit, you need to be aware of the risks, you need to plan carefully. Too many people just jump into a flooded river without thinking