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сряда, 21 май 2014 г.

Taming the floods, Dutch-style

It is 100 days since David Cameron visited the submerged Somerset levels at the peak of the winter floods that devastated swathes of England and hundreds of broken flood defences have now been repaired thanks to £270m of emergency funding from government. But in the Netherlands, also battered by the record deluge but relatively unscathed, an ongoing multibillion-euro programme continues to reshape the watery nation, with none of the political storm whipped up in the UK.

Hard-won reclaimed land – polders – are being given back to rivers and meanders are being cut back into flood plains, all as part of a back-to-nature approach that is reversing centuries of battling against water, in favour of finding ways to live with it.

The Netherlands is a land of waterways and a quarter is below sea level, with 60% of its people in flood-risk areas. There is deep experience of what it takes to deal with flooding, in both financial and human terms.

Jan Kant is the fourth generation of his family to farm the Noordwaard polder in the heart of the giant four-river delta than dominates the south of the Netherlands. "I am attached to this area," he says simply. But, with his sons who now run the business, he is about to move away. The dykes protecting Kant's low-lying fields are about to be broken and the area flooded, to take 30cm off the river level that threatens the nearby town of Gorinchem.

The intensification of downpours by climate change is the underlying reason and Kant is now philosophical about losing his farm: "Living in an area like this, we may have had to move someday anyway."

Another 10 farmers and 24 other families are having to make way as the river takes possession of its flood plain once more. The project is the biggest of 34 "Room for the River" (RR) projects across the Netherlands, costing €2.3bn (£1.9bn) and set to finish in 2015.

But discussions with the locals began more than a decade ago, led by Raalf Gaastra, the stakeholder manager for the Noordwaard polder RR project.

"People have made their own choices: they can stay in an area that could now be flooded tomorrow, because they like the area, or they can leave," he says. Those who stay are helped to build new homes, raised on high mounds, those who don't are bought out at market rates. "The first discussion is not easy, but once one house has decided to go people start to follow," says Gaastra.

Vic Gremmer, the local residents' spokesman, is staying and moving to a new house. "Being forced to move so other people can keep their feet dry is acceptable," he says. "The key is to make us safe and compensate us properly."

The disruption is enormous: new bridges, roads, pipes and repositioned dykes are all in construction, leaving great muddy tracks across the flat green and blue landscape.

"Sometimes it feels like the work takes ages," says Gremmer. But the nature-lover is excited by the prospect of new waterworld and the ospreys it will support. "I can't wait to see what it looks like."

The Noordwaard polder is strikingly similar to the Somerset Levels in the south-west of England, down to the locals initial insistence that river dredging was the key. But Kant, Gremmer and the rest were eventually persuaded that annual dredging was not a sustainable solution.

Visiting the Noordwaard polder, David Rooke, director of flood and coastal risk at the UK's Environment Agency, says: "It's exactly the same issue as the Somerset Levels, exactly the same. But [in England] there is not €2.3bn to solve the problem." Projects like Room for the River have also gone ahead in other countries, such as Germany and China. In England and Wales, which together have actually a 50% greater area of land below sea level than the Netherlands, the last Labour government began a similar project, called "Making room for water."

"But then there was a change of government and a change of policy," says Rooke. After the coalition cut annual flood defence spending by 25% on taking office in 2010.

In the Hague, at the Rijkswaterstaat, the national water management agency which runs the Room for the River programme, director of safety Roeland Allewijn, says over €16bn has already committed for flood defences up to 2028. "We call this relatively short term.

"There is huge political and public awareness that we need to spend a lot of money on this," he says. "It is reasonably easy for us to get government spending on this." This stems back to the national disaster in February 1953, when a North Sea storm overwhelmed the coast and killed 1,850 Dutch people.

The sea remains as major flood threat to the Netherlands and on the windy coast, not far from the major cities of Rotterdam and the Hague, a €75m government-backed experiment is taking place. A new crescent-shaped peninsula, 4 miles long, has been created just in front of the sandy beach. The idea is that rather than having to replenish the beach every year to protect the coast, the waves and currents will wash the 20m cubic metres of sand used to create the peninsula into place: the project is called the "sand motor".

The new peninsula has already been stretched to 5.5 miles in its first two years, and has provided a new site for recreation including hunting for the fossil mammoth teeth hidden in the ice-age sand dredged from offshore.

"There was not a big need to show a cost-benefit," says Jaap Flikweert, an engineer at Royal Haskoning DHV. "There was a lot of vision: it's very Dutch." Flikweert is now examining how the sand motor might be used in the UK, and has identified coastal locations off the low-lying counties of Lincolnshire and Suffolk, both places hammered by the winter's storms.

Paul Cobbing, chief executive of the UK's community-led National Flood Forum, says the British approach is different: "In the UK, the cost-benefit analysis would have had to be foremost to get anyway near Treasury funding."

The sand motor's primary aim is to guard against the rise in sea levels being driven by climate change, and global warming is always the first reason cited by Dutch engineers for the huge flood defence improvements being undertaken. There is no debate about its impact, according to Peter Glas, president of the Dutch Association of Regional Water Boards, the 23 elected bodies that raise €2.5bn a year in flood defence taxes and have defended communities for many centuries. "I don't even enter into discussions about carbon dioxide," he says. "I see sea level rising, I see the land falling and I see millions of people in need."

Aidan Kerr, a flooding expert at the Association of British Insurers and formerly at the Environment Agency, does not see the same attitude in the UK, where environment secretary Owen Paterson is widely regarded as a climate sceptic. "There is concern about the extent to which climate change projections are being taken into account," he says. "The EA has done work on the impact of climate change. But this is not being taken into account as a benchmark for funding."

Water Boards president Glas is also chairman of the local De Dommel water board in another part of the delta region. Here long, sinuous meanders have just been dug through fields to recreate the natural winding form of the Esse Stroom, slowing the rush of water towards populated areas downstream and creating more room for water. The Esse was part of the huge 1995 floods and closed the A2 motorway which runs from Amsterdam to Milan, causing over €6bn of economic damage.

The new meanders, and fields newly opened to floodwaters, account for about 6% of the total 150,000 hectare area of the De Dommel water board and will be able to store 20m tonnes of water. The EA in England has also restored meanders at Stockton-on-Tees and in Oxfordshire, but on a much smaller scale. Such back-to-nature projects, like another pilot scheme in north Somerset, challenge centuries of accepted wisdom that rivers must be straightened and water flow speeded up. "It can be a leap of faith for local communities," said Rooke, noting that the early results in Somerset look promising.

Mark van de Wouw, hydrologist at the De Dommel waterboard, looks at the newly cut meanders in the Esse and says: "It is a small sacrifice to save a massive cost if a city floods downstream."

Van de Woew visited No 10 Downing Street in February as part of a Dutch delegation that advised on the UK's flood response. "The biggest difference was a difference of culture. In the Netherlands, we have a totally different approach to the problem: people here expect to pay bills for flood defences."

Flikweert agrees: "Flooding in the UK is more difficult to treat because it is more diverse. So in the Netherlands you have a simpler problem with more money, compared to a more difficult problem with less money in the UK."

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Room for the River Programme

The residents in the river region were confronted anxious times in 1993 and 1995. The water levels were extremely high and the dikes just managed to hold. A quarter of a million people had to be evacuated.

Extremely high river discharges will occur more frequently in the future and for this reason it was decided to ensure that the rivers could discharge the forecast greater volumes of water without flooding. The Government approved the Room for the River Plan (Approved decision Room for the River)(2,5MB) in 2007.

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This Plan has three objectives:

  1. by 2015 the branches of the Rhine will cope with a discharge capacity of 16,000 cubic metres of water per second without flooding;
  2. the measures implemented to increase safety will also improve the overall environmental quality of the river region;
  3. the extra room the rivers will need in the coming decades to cope with higher discharges due to the forecast climate changes, will remain permanently available.

The rivers in the Dutch delta are sometimes required to process huge amounts of water in very little time. In order to limit the risk of flooding, Rijkswaterstaat (the Dutch department for Public Works and Water Management) is working on the 'Room for the River' programme.



Relocation of dykes

Dykes will be relocated farther from the river shore. This will create additional space within the flood plain for the river during annual floods.

Lower the level of floodplain

In addition to the relocation of the dykes, the floodplain bottom will be lowered in depth. Increasing the depth in the floodplain must occur due to the collection of sediments in the area after years of regular flooding.

Reduce height of the groynes

The groynes within the riverbed will be lowered to allow for more drainage to occur during an increase in water levels more quickly than presently positioned. Groynes will be added in specified locations in addition to the modifications occurring to the existing structures.

Construction of a "Green Channel"

A "Green Channel" will be constructed serving as a flood bypass around Veessen-Wapenveld.

Increase the depth of the side channels

Side channels will be lowered in depth to increase the barrier between the river and infrastructures and residents. It will also allow for more water to be removed from the flooded location thus reducing the breach of the dykes.

Removal of obstacles

Locations along the river where there are obstacles will be addressed. For example, the hydraulic bridge at Oosterbeek will be removed.

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