floods will happen, no matter what humans try to do. The hill farmers who live and work upstream should be paid to manage flood waters on their land, that has to be cheaper than paying insurance.
But often caused by humans. Stripping the hills of their ancient forests to create those hill farms was the original cause of the flooding tendency.
We had an equivalent on our housing estate on South London's fringe. The higher land at the end had been farmed for at least 400 years and manuring and ploughing in mulch over the centuries had built up about three feet of soil above the chalk downs underlay, a perfect sponge absorbing heavy rainfall.
Then the 500 acres was bought for a golf course and to construct that all the soil was stripped off and the chalk contours reprofiled. Then the soil was shuttered and all the flints and stones removed and graded.
Finally the fairways were laid with a thin layer of soil and small stones, the rough with mostly a coarse stone and soil mix and the greens with finest soils and sands. The huge surplus of quality soil and flintstones were sold off.
The outcome was that the end of our estate suffered severe flooding as the water raced off the slopes, something that had never happened to that land in local records going back 1000 years.
So the golf course constructors had to think again, cutting in long water trenches as temporary retainers and raising high curved bankings like dams to temporarily hold back the downward rush of water. It's still not right many years later, only it's now just the road that floods like a river and not the properties.
.
