It’s pretty simple – don’t build in flood prone areas in the first place. If you do/have/too late then think seriously about raising the floor height above the flood limit. This was done a lot in Brizzy after ’74, and has been done in my rural, river-focused, flood-prone shire. There’s not much anyone can do about flash flooding in areas that don’t normally flood, like Grantham, but Council/State could build levees and diversions to minimise effects in future.
One obvious thing to do, if you’re in a house on stumps is to fasten the bearers to the stumps, so the house doesn’t float off them. They aren’t normally fastend to the stumps because this can compromise termite security. But hoppiron strapping on every stump, strapping down all the bearers, means the flood has to lift the house ands the stumps right out of the ground to move it.
Another good trick, especially if your stumps are just that – short sections of timber or concrete sitting on the ground, is to dig around each stump (or at least those on the upstream side of the house) and conrete them in place.
Another useful tip is to build earth berms on your propert boundary or (if rural) on the upstream side of the house, built a bit like a barcan dune, in a curve so that the ‘tails’ of the curve point downstream and help direct any cross-land flows around the house rather than into it or under it. This slows the force of the water that DOES get under the house, greatly reducing its impact. Another good thought is a permanently fixed ladder next to the ceiling manhole, and a corresponding trap door in the roof, so you can – in a complete emergency – at least get onto the roof without being swept away.
An ‘emergency pack’ is another good idea. Like being on a sailing boat in mid-ocean, you never quite know when spomething bad MIGHT happen, so (like the Scouts) – be prepared. A small back pack with a pack of muesli bars, a length of rope, a couple of space blankets, and a litre or two of water (which could be checked/changed on a regualr basis) with a hand held self-powered torch and maybe a self-power (hand-wound) radio as well, so you can flash at the rescue guys and listen to what’s going on aorund you on the radio.