Floating objects keep getting pushed to the centre of the flow making it nigh impossible to self-rescue. This is when you need companions who are up to the task of getting to you and getting you back in your boat in the same conditions that caused you to go for a swim. White water accident statistics from all over the world make sobering reading. In the case of the high water deaths, the cause was either hypothermia or injuries received during a long swim. In many cases the swimmer deaths were preventable if there had been capable rescuers available downstream of the capsize.
Urban rivers present a special set of dangers.
Nasty bits of steel stick out from bridges, there are weirs, fences, trees and even park benches that can become deathtraps once you add water. Plus it's a public place, so please remember the copycat factor. It happens all the time. This rise in flow is typical of New Zealand's rain fed rivers. The Aorere River at 20 cumecs.