Regarding some of the new build houses being flooded its simply because they are built on old flood plains. All right perhaps the last time it was flooded was 100+ years ago but it doesn't take a genius to work out that if an area floods every hundred or more years then it will flood again.
Why planning permission gets passed for houses built in these areas I just don't know. I can only assume it comes down to 2 things money and greed.
Perth is not far away from me and they have had a terrible time in the past 10-15 years with floods and many of the houses that are affected are bought new build houses. Obviously they were built in a stupid place, I feel very sorry for anyone who has bought a house like this, not only do you have the pain of losing possessions etc but you can't sell the house on. Who would buy a house knowing it had been flooded recently and might be/probably will be flooded again. I'm sure if the owners had been told before purchase they would never have bought them in the first place.