It appears that it is turning into a problem in Italy for another reason. In mountainous regions the streams would be maintained by the people owning the land. With people leaving the area the waterways are left unmaintained leaving debris such as large trunks as branches in the water. This effect is compounded by that the land that remains “actively” owned is divided amongst many descendants that can never agree to either fix something or pay to get it fixed.

The consequence of all this is that water flows less freely and that when there is a lot of rainfall it comes not just with water but also large amounts of trees and stones.

I imagine this happening in many places.