Having built a site on a flood plain, I can tell you there are quite a few regulations to jump through and things are quite carefully considered. Or at least they were with the developer I worked for. We built 14 houses in Chertsey - the year Chertsey was underwater and the army had to be called in. I know what we did worked because we were under 2ft of water at one time! The regulations around not building up ground artificially, stopping foul pipes from backing up into the house and allowing the free flow of flood water around the houses was all thought out and a necessity of the planning. Just so happens the one in 100 year flood event happened the year we were building it. So it is thought about when planning is granted on these higher risk land parcels, it just might not be enough.
I think what we are experiencing is beyond what those in the planning department/ environment agency foresaw and lessons will be learnt from this winter. The question is, how high do we build the defences because if this constant wet weather is to become a regular occurrence, there's no point building them to this years watermark - they almost need doubling. I know the EA are investing in improving flood defence as I've been asked to tender for some of the jobs. This was before this winters rain. So it is happening, just without the fanfare the papers expect.
The pictures below show some of the details we had to incorporate into the build. The oversite had a 450mm void under the floor with "vents" to allow flood water to enter under the building and recede without causing any damage. The floors of the void were concreted and laid to falls to allow the water to flow out. Even the perimeter wall had vents in to allow water to flow through. It was all thought out.
no one in their right mind is going to buy any of those ..... WTF is going to insure them for starters ???


as said the voids are simply going to fill ..attract vermin, etc. ..... been a few round here built on raised mounds, where there's a risk, as a lot are in Europe ... any risk and they're raised maybe 10 feet .... has certainly worked fine in a lot of locations
my old w/shop site was a nightmare for
perceived flood risk, even though it'd never flooded in living memory, EA dictated it was right on the edge of a 1:1000 yr event risk zone, so whole acre site was raised by two feet, despite the fact that:-
it was
already 5 feet above the surrounding area (no topographic study done on the ground - all LIDAR mapping)

and
I had photographs of flooding from '78,
which was the worst Aber has ever seen in living memory, 4 feet below their predicted high water map.
Plus; there had been a massive flood prevention scheme undertaken, in the late 70's, re-routing the main contributory watercourse, away from the town in a 12ft culvert, direct to the river ... they (EA) conveniently had no knowledge of it

... I knew the guy who was in charge of the project at the time for Welsh Water

and went and photographed it all ... and had a lot of drawings, etc. for it,
extracted from EA records
Basically the EA's .. (or whatever the tw*ts're called now) LIDAR based maps are so unrealistic they might as well burn them ... the flood risk map for Abergavenny shows most of the town under water, with the bits that aren't, at the lowest levels and the wettest bits 30-40 ft above them .... anyone with half a brain cell and some local knowledge can see how farcical they all are ...
I dare say that most other places have similar problems, that local knowledge'd recognise
