Is Britain becoming more prone to floods?
Probably. Over the past 15 years or so, major flooding has become more or less an annual event. In 2007, we saw the worst floods since 1947, and many parts of southern Britain have just had their wettest January on record, hard on the heels of the massive storm surges seen over the Christmas period.
According to government figures, 5.2 million houses are at risk of flooding in England. It can't be said definitively that flooding is getting worse, however, because although the UK has detailed temperature and precipitation data stretching back centuries, data on rivers and flooding only began in the 1960s.
Equally, it cannot yet be said with confidence that global climate change is to blame although all government predictions and long-term planning are based on the assumption that these islands do face a wetter, stormier future.
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Why is Britain set to get wetter?
Because global temperatures are rising. According to meteorologists, for every 1C of temperature increase, the atmosphere holds an extra 7% of water. Also, hotter air is more volatile. What this means for Britain, where the weather is frequently shaped by low pressure systems sweeping in from the Atlantic, is more rain and more storms.
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Richard Ashley of Sheffield University, who wrote a major report on flood risks for the UK government in 2004, predicted then that winter rainfall would increase by up to 15% by 2050 due to climate change.
After the major floods of 2007, another study based on the latest climate-change models predicted a 25% rise. A government analysis puts the increase in flooding risk by 2080 at anything between 70% and 400%.
What about rising sea levels?
As the collapse of Brunel's main rail line to the southwest last week reminded us, the ocean is a powerful adversary. Britain has 17,381km of coastline more than Brazil or India. An unusually high 45.6% of England's coast is already fortified by sea defences, such as sea walls, groynes or artificial beaches, despite the fact that hard defences on one piece of coast merely moves erosion along to another.
The most recent survey of expert views (published in last month's Quaternary Science Reviews) suggests that the sea level is likely to rise by between 0.7m and 1.2m by 2100 worsening coastal erosion and putting a million UK houses at risk of sea flooding.
Can we do anything about it?
Perhaps not. Some argue that attempts to control nature are ultimately doomed: that all the money spent on flood defences, such as dredging rivers or building concrete flood barriers, will in the end exacerbate, rather than solve, the problem in part because they encourage the false idea that man is in control.
"What we've been doing over the past 100 years is trying to turn rivers into canalised systems where you quickly zip water down to the sea," Peter Smith of the Wildwood Trust told the FT. That might help to keep farmland clear of flooding, but it increases the risk of catastrophic flooding in urban areas downstream.
Why all the focus on dredging then?
In part because the issue highlights the radical differences of opinion on how to tackle centuries-old challenges, such as how to limit flooding on the Somerset Levels. Much of the local anger concerns the failure of the Environment Agency to dredge sufficiently the rivers Tone and Parrett ie, clear the riverbed of silt using diggers or pumps to get rainwater flowing through quickly without overspilling the banks.
Yet, expert hydrologists say this would not have been enough. "The idea that dredging on its own would have made the difference over the past month is fanciful," reckons Hannah Cloke of Reading University.
How could Britain adapt?
In the long run, it will need to devote more of its resources to the issue, while developing policies more focused on mitigating damage (such as not allowing 200,000 new houses to be built on flood plains, as in the decade to 2011) rather than building ever more hard defences.
Spending on flood defences rose after the floods of 1998, but has dipped sharply in recent years (despite some pretty outlandish claims and double-counting by the government this week) to £2.34bn over the 2011/2012 to 2014/2015 period.
But according to government research, even the cost of maintaining the existing levels of flood defence will rise to £1bn a year by 2035, while the annual damage done by floods is set to rise from about £1.1bn today to £27bn by 2080.
These kinds of figures make the £130m boost to spending in the wake of the current floods look like the proverbial drop in the ocean.
A subsidy for insurers
From 2015, the government is backing a new subsidy agreement with the insurance industry, known as Flood Re, designed to ensure that householders in 500,000 of the properties most at risk will be able to find insurers willing to take them.
The scheme involves a levy of £10.50 on all household insurance policies, and a payment of up to £540 a year for the flood-insurance element of those properties in flood-prone areas.
That's good news for those who live on flood plains. But it might arguably turn out to be bad news if it becomes a de facto government guarantee that encourages developers to continue building on vulnerable land.
