I noticed, with interest, some local farmers are understandably worried about the risk of flooding due to build-up of silt -m a situation not helped by a failure to cut back trees and vegetation from the banks of the Ouse (Trees on river banks worsening flood risk, September 10).

River banks do need management, but one aspect not addressed is the root cause of the problem - where is this silt coming from?

Some of it is due to natural erosion within the river itself, but most comes from human activity upstream, including soil erosion and run off from roads, construction and so on.

The only way we are going to achieve more vegetation and biodiversity along our river banks and still manage flood risk is by getting much better at reducing silt entering our rivers in the first place.

David Farnsworth, Old Orchard, Haxby