Flooding: five lessons we have learned
Concrete is no longer a solution
For centuries flood protection has meant building ever higher walls and radically straightening and clearing rivers, to rush water ever faster to the sea. But a more crowded island, rising sea levels and increasing extreme weather caused by climate change mean the hard engineering approach is hitting its limit.
Dredging is a prime example: experts say it would not have prevented flooding in the Somerset Levels, nor drained the water significantly quicker. A desire for immediate action is understandable, but a massive amount of rain has fallen on the Levels, far greater than the capacity of the river channels, and large parts of the Levels are below sea level – the water has to go uphill to the coast.
Instead, a “back to nature” approach is being successfully tested to return water systems to the sluggish, slow systems they once were, using fields as temporary ponds, blocking up drains and even allowing fallen trees to obstruct streams.
Soft flood defences mean hard choices
Good, fertile farmland has been prized since the dawn of agriculture and Britons have spent a millennium draining marshes and creating coastal land by holding back the sea in order to create new fields. But today our villages, towns and cities are prized even more.
If the soft “back to nature” approach is to be expanded on the scale required, a new settlement is needed with farmers that balances food against floods. Payments will need to be channelled to landowners in key areas who allow their fields to store water during wet periods.
In places like the Somerset Levels there will be hard choices for people, too. Many flood experts predict the Levels will have to be abandoned to the sea before the century’s end, as the cost of keeping the water out spirals out of control.
Retreat is also under way on the coast, where sea walls are being smashedby Salt marshes will reappear, but often they sap the energy of the waves and therefore offer better protection to nearby homes.
Flood protection often works
Despite the thousands of homes that have been flooded during this sodden and stormy winter, about a million have been protected by the defences that held out. But, with the risk rising, experts warn it is impossible to stop all floods.
The focus needs to shift towards households being prepared for flooding, particularly as flash floods – which can strike anywhere – are expected to increase as rainfall intensifies in a warming world. Measures can be simple: from inflatable toilet bungs to stop sewage overflows to slot-in door protectors. Others reduce the cost of flood repairs, such as rewiring electrical circuits nearer ceiling level. On some flood plains, people are even building homes on stilts.
Cutting flood defence spending is a false economy
This winter’s floods have already caused at least £1bn of damage to homes, businesses, roads and other infrastructure. That is almost twice the amount that will be spent on flood defences this year. In fact, in the longer term most flood defence schemes are expected to save £8 for every £1 invested. But annual government spending on flood defences will fall by 15% in real terms under the coalition, about £90m a year, and hundreds of projects across the country remain on hold. The government’s official advisers, the Committee on Climate Change, calculate that these cuts will result in £3bn of future damage. Furthermore, because the risk of flooding is rising, the committee calculates that between 2011-2015 the coalition is spending £500m less than would be needed to keep flood risk at the same level.
Climate change appears to be hitting harder and faster than feared
A government study in 2012 – coincidentally England’s wettest year on record – identified increased flooding as the greatest impact of climate change on the UK. It is already being felt. The extensive floods in England back in 2000 were made twice as likely by global warming, according to scientists.
Warmer temperatures lead to more moisture in the air but also more energy in weather systems: the result is more frequent severe downpours On the southern coasts, the sea has already risen 6cm in two decades, bringing storm surges nearer – or over – the top of sea walls. Sea levels could rise by almost a metre this century. Planning to cope with this rising flood risk began a decade ago, expecting it to be felt in the 2030s. But experts say it is hitting now.