Areas like the fens and the reclaimed marshland where I used to live do not have pretty natural streams and ditches, ugly and featureless as they are, are a necessity.
I was watching a programme last night which was very interesting. It was Northumberland I think. They were tackling the problem of flooding at source. Firstly by partially blocking tiny streams with fallen tress, etc, and slowing down the rate of flow. Then there were wooden barriers that contained mini floods, but allowed the water to leak slowly down hill. Both these methods allowed the rivers into which this water was to flow time to deal with increased rain water, by slowing down the rate at which it entered the bigger rivers.
The authority had been told flood defences would cost £2 million but these flood prevention methods (using natural materials such as wood) cost £250,000.
Like dredging, this sounds like one approach that could partially alleviate the problem.