sillyoldfool to my knowledge the legislation that applies as riparian owner is the Public Health Act 1936, the Land Drainage Acts of 1991 & 1994, the Water Resources Act 1991 and some local Land Drainage Bylaws. My understanding is the EU Directive is more about water quality and nature conservation. There is a connection though around the permissions from the Environment Agency you need to carry out certain work and making sure any standing water is not polluted. I think the majority of work going on around the EU Directive is connected with river basins.
Watercourses like ditches and culverts are designed to drain surface water away, before the water levels increase to an extent that puts property, roads, land and infrastructure at risk of flooding. If the system of ditches and culverts are well maintained, any flooding is likely to only affect areas in the floodplain. DEFRA has a regulatory role as well as the EA and other bodies.
JessM I'm not sure if your post is supporting my earlier one or not, but I am not suggesting in any way that new flood barriers should be built, quite the opposite. I wasn't really thinking about trees, although they obviously play a role, I was thinking of the loss of hedgerows, unmaintained ditches, change of farmland usage, etc. Even the loss of garden lawns is a contributing factor to water drainage. The location of Cumbria with its steep mountains and rivers makes it a target for flooding as our winters get wetter. And the milder our winters are, the wetter they can be. Hopefully Cumbria County Council being appointed as a Lead Local Flood Authority after the terrible flooding in 2009, means it will have the expertise to carry out a comprehensive review of the latest floods. My worry is the government will keep councils starved of funds to carry out essential maintenance.
I am not an expert on this, I've just read a bit about it.