Let them create more wildlife ponds upstream, so that excess water is captured there and the rate of emptying into flood plains is slowed down. Plant more trees (see Bags list) strategically, dredge the ditches and rivers and (see Elegran's post somewhere) bring back the beavers.
Problem, if not solved, at least alleviated, and we're not bring paid megabucks, and given peerages, to sit on some committee.
Using the Verb Get or variations of Get
Terrible relationship with DIL - am I the problem?



, and bracken, and rushes....
and
at your last two comments, aka.