In my hometown there was a regular flooding about every ten years, that put around one meter of water in the middle of the town. So they built a ‚big‘ (for that town) Damm to keep the water away.
They did make it just high enough to prevent a flooding for all but the floods that happen every 100 years.
Should that particularly high flooding come though, the Damm will break and the town will be gone.
That Damm is now about 50-80 years old, and floods will likely become worse with the climate catastrophe.
I think nobody knows what will happen if that ultra high flood occurs.
In 2002 Germany had one of its worst floods in centuries. Some towns were literally washed away, dozens of people were killed, billions in damages.
The federal and state governments paid for extensive flood protection programmes after that.
A friend of mine lived in a town who voted against it. The logic of these stupid yockels? The flood was a once in a century flood,so they should be good now. And a flood wall would impede the view, their historic downtown center wouldn’t be as nice anymore,etc. So they refused a flood protection system the community wouldn’t have to pay a dime for.
In 2013 there was a far worse flood. But damages while still substantial were far smaller than 2002. Because of the better protection in most places. The town my friend once lived in? It got flooded the second time, sued by its neighbouring towns because they got flooded from there.
