Had the story told not been so bleak, the Environment Agency's live online flood warning map would be comical.

From Bridlington on the North Sea coast to west Cornwall, England and most of Wales disappear beneath a forest of red and orange virtual pins. If this was a map of a war zone it would show a mighty battle going on. Or rather, a series of battles.

At the time of writing, the English agency's graphic, updated every 15 minutes, shows 16 severe flood warnings, 132 flood warnings, and 228 flood alerts. The southern half of the island is discovering what happens when an old cliché - the British weather - becomes something malevolent. Thousands are miserable, angry, or both. The Government is losing in the struggle to contain the waters and public outrage.

Blame has been descending with the ferocity of a rain storm on those paid to manage crises. How did this happen; what's being done; how can it be prevented from happening again? For the moment, those afflicted are not much interested in theories of river management, climate change, budget cuts or Treasury rules. But when they get the chance the questions will come thick and fast. Unlike the waters, anger will not subside.

Different maps show different things. Chart the political constituencies of England and you find that the areas where flooding has attracted most attention are also the areas where Labour struggles for a foothold. In 2010, "the south" - generally defined as the south-west, south-east and east - returned only 10 MPs for the party from 197 constituencies. This is a political crisis for the Coalition. Overwhelmingly, their voters are in the front line.

David Cameron understands the fact well enough. A Prime Minister does not cancel a Cabinet meeting, as Mr Cameron did yesterday, unless there is a pressing reason. It is one thing to tour devastated areas, to take charge, to reassure and show concern. But the blunt fact is that the flooding has exposed the Coalition to scrutiny from core voters liable to wonder about the people they have elected.

What might those voters ask? They could rightly wonder if spending cuts and reduced staffing at the Environment Agency have exacerbated the crisis. They could question a shambolic ministerial response. They could ask about politicians more concerned with tawdry attempts to shift blame than with the victims of flooding. This is the sort of crisis that can damage governments irreparably. Confidence, where it existed, is shattered.

The overriding issue is one of simple competence. Mr Cameron's ministers, the preposterous Eric Pickles first and foremost, have seemed much more interested in depicting the Environment Agency as culpable than in coming up with answers. Not content in attacking Lord Smith, the agency's chairman, the communities minister has also criticised government experts and "apologised" for decisions taken by his colleague Owen Paterson, the Environment Secretary.

None of this is clever or edifying. It was not redeemed by Mr Pickles claiming that his "admiration for the Environment Agency exceeds no-one". The use of language was almost as inept as the Government's handling of the crisis. Meanwhile, Tory and Liberal Democrat MPs have been left to cope with furious constituents from the Thames Valley to Somerset, voters who might otherwise have been content to fret as usual over immigration, "welfare", or fuel bills.

Predictably, Ukip's Nigel Farage has been quick to enter the fray, endorsing a demand for overseas aid funds to be redirected to flood victims while offering up his usual scorn for what the MEP calls the establishment. Hence Mr Cameron's self-evidently urgent desire to get a grip, finally, on his Government's response to the floods.

One recent poll predicts that Ukip will secure 20% of the vote in May's European elections. Given that Scotland disdains Mr Farage and his party, the figure will certainly be much higher in the English south, at the heart of the crisis. Tories might care nothing for the European Parliament, but anger over the floods could well give Ukip the kind of breakthrough it desires. That would concentrate minds in the Conservative Party and alter the nature of Westminster politics for all of us, even in a country with a single Tory MP.

Mr Cameron can neither walk on water nor stop the rain. He cannot open the eyes of numerous backbenchers who refuse to see evidence of climate change, or persuade those who have never encountered a green field that couldn't be improved by housing. The Prime Minister can't deviate from the language of austerity, but equally he cannot refuse to spend public money (perhaps a great deal of public money) to ensure there is no repetition of flooding on today's scale.

Beyond the party political game, there are political questions. The argument over local river dredging is almost incidental to the challenges that a government, this one or another, will have to address if severe flooding is not to continue to be an annual event across England. If this is what the 21st century holds, politicians are facing an issue that can't be fudged.

If inundations are to be accepted as inevitable a great deal of prime real estate will have to be sacrificed. A lot of voters, I suspect, won't tolerate that. So will they tolerate the kind of spending required for flood defences in the Dutch manner? In parts of riverine England, that sort of inquiry is no longer a joke.

It is certainly no joke for a Tory Party dedicated to shrinking the state. You cannot, if sane, privatise the management of civil defence. Gordon Brown was confronted by floods within weeks of taking office as prime minister. It turned out to be one of his better periods in Downing Street. But the Labour leader was another who made lots of promises after flooding followed budget cuts. Money would be spent, problems would be fixed. Instead, the politicians have crossed their fingers and hoped, like Noah buying an umbrella rather than building an ark.

Some of that is still going on. Those evacuated from the Thames Valley must be heartily sick of hearing of "freak" rainfall, the worst since records began, as though a lack of useful precedents is a guarantee that floods will not return next year or for years to come. Climate change makes all of the records meaningless. The gulf stream is not obedient to government policy. If the world is changing then society, politicians must also change.

Will Mr Cameron worry more about that than he worries about Ukip? Will any of the Westminster parties, Greens aside, begin to realise that another quick fix won't do? A deep-dyed optimist might believe it. Those who begin to tot up the vast economic cost of England's crisis will be less sanguine.

Reality approaches like a rising tide while the Prime Minister parodies the Canute myth. But if voters in his party's heartlands decide he has lost control of the security of their homes, fields and lives the price they exact will be high. Some foul weather lies ahead for the Coalition Government.