Prince Charles has linked the flooding in England's Somerset Levels with climate change.
Homes in Devon and Somerset were evacuated on Thursday with flood defences no longer able to cope after a series of heavy storms across England's southwest.
Fourteen people were rescued from their homes as specialist water rescue teams were launched to evacuate residents and pets from towns including Burrowbridge, Thornfalcon, Stoke St Gregory, Moorland and Exeter.
Residents have had to watch as their land and homes have rotted underwater since the end of December, and now more than 150 homeowners face fresh misery as defences risk being "overtopped" and police are advising those in Fordgate and Northmoor to leave their properties.
"Police officers and volunteers have knocked on doors or called on the phone to deliver the advice that they should leave immediately," a police spokesman said.
Prince Charles, who visited Somerset on Wednesday to see how residents and farming communities are coping after being cut off by floodwaters for weeks, yesterday said the flooding was a classic example of what happens if society pays little attention to the accumulating impact of climate change.
Speaking at a leadership summit in east London organised by his Business in the Community organisation, he told delegates and business leaders: "And incidentally I was down in Somerset this week and it is, I think, a classic example of what happens if we pay little attention to the accumulating impact of climate change on the larger picture.
"What we're increasingly finding now, I think, is that we're having to deal with the symptoms, and tinker with them, which is going to become ever more expensive."
He said one farmer told him his bank had said the flooding in the area last northern winter was a "once in a 100 years" event but now it had happened again.
"What it does, of course, is to kill off the soil, and you have to apply huge amounts of lime to try and bring the soil back again," the Princesaid.
"And it's just perhaps a bit of a reminder, possibly, and a wake-up call, that we have to take a longer-term view because if you're going to grow anything and farm it, the weather is hugely important in all this. You can't just suddenly remove the help from people."
The evacuation of homes came as Prime Minister David Cameron announced that the area would get government assistance of 10 million ($19.8 million) for urgent work.
In total he pledged 100 million to fund essential flood repairs and maintenance over the next year, with a further 75 million for repairs and 15 million for extra maintenance.
On his visit to the area Prince Charles pledged a 50,000 donation. The Duke of Westminster will match the funding with an additional 50,000 - taking the total donation to 100,000.
"The tragedy," said the Prince as he surveyed the scene, "is that nothing happened for so long."
He added: "There's nothing like a jolly good disaster to get people to start doing something."