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Green riverbanks could avert disastrous flooding

The German Environment Minister Barbara Hendricks this week visited areas of the river Elbe that were hit by disastrous flooding last year. Could greener river management help avoid a repeat catastrophe?

Extreme weather events with storms and torrential rain appear to be on the increase, which is putting flood protection higher on the agenda than ever before. So experts like Emil Dister are in great demand: When Germany gets inundated, people turn to his institute to ask whether modern society has made too many unnatural changes to the country's riversides. The director of the WWF-Auen-Institut, or floodplain institute, in Karlsruhe is convinced that the disappearance of natural river floodplains is connected to the severe flooding.

"In its natural condition, a river creates a wider bed for itself. Before humans started to intervene, even extreme amounts of floodwater could flow off onto the green areas along the banks," Dister explains. "Now we have drastically reduced these natural river floodplains, so there is a much smaller area available to cope with the same amount - or sometimes even an increased amount - of water."

Germany's Federal Agency for Nature Conservation calculates that Germany has lost on average 80 percent of its river floodplains. They have given way to housing, industry or intensive agriculture. Dister says numerous studies show that this is the case in the areas of eastern Germany which have been heavily affected by devastating floods in recent years.

The Elbe waters flood a walkway in Magdeburg (Photo: Jens Wolf)

There's no room for the Elbe to spread out in Magdeburg

Along small rivers, floodplains have often been sacrificed to building activity, says Dister. With the bigger rivers, he sees intensive agriculture as the main problem. Heavy farm machinery compresses the earth. Various crops and methods of cultivation decrease the land's ability to absorb floodwater.

Conservation groups have been calling for riverbanks to be restored to their natural function as floodplains for decades - in vain, says Olaf Tschimpke, head of the German environment group NABU.

Germany's states have been investing primarily in technical measures like flood barricades and higher dikes, he says - which is simply not enough.

"Without floodplains, our options for coping with rising river levels are severely limited," Tschimpke says.

What's needed is "living rivers with free banks," which would not only help protect against flooding but also conserve nature, he adds.

No good replacement

The conservation group WWF has a similar take: The authorities have relied too much on improved weather forecasting and manmade flood barriers.

"Repairing and raising dykes might be a good idea in individual cases, but it often just shifts the problem downstream to a neighboring community," warns WWF hydrologist Georg Rast.

A flooded village along the Elbe (Photo: Arno Burgi)

Artificial flood barriers instead of nature?

He refers to a 2007 WWF study on prevention measures along the flood-prone Elbe River, which found that if all the plans to remove dikes along the riverside or shift them back further were carried out, this would only restore 1 percent of the original flood areas.

Dister, whose institute was first set up by the WWF in 1985 and is now part of the Karlsruhe Institute of Technology, says it could be time to consider a more differentiated approach to flood management.

"That would mean that in the case of major flood events like the ones we have now, we would have to deliberately flood areas used for agriculture to protect urban areas or industrial plants."

Conservationist Tschimpke is calling for a pact with farmers to make this possible. He envisions compensating them for converting riverbank areas back to a more natural use, and allowing them to flood when necessary.

WWF's Georg Rast puts the message in a nutshell: "The floodwater would be better on the fields than in people's living rooms."

Floodwater from the Danube River submerges houses in the village of Fischerdorf on June 7, 2013 (Photo: Christof Strache)

This Bavarian village could not be protected from the floodwaters of the Danube

In some areas, artificial levees or retention basins have been opened up to take on floodwater in case of emergencies. In some cases there may be no alternative, says Dister, adding that this is not a satisfactory alternative to natural floodplains.

"If these basins are only flooded in the case of a catastrophe, that is a catastrophe in itself for the organisms living there," he says. "They are not able to adapt to flooding. In natural floodplains you find all sorts of life forms that have adapted to regular flooding and cannot exist without it."

Increase in extreme weather events

After the major floods which struck the Elbe River in 2002, the German authorities set up extensive flood protection programs. But now, more than 10 years on, the risks have hardly been reduced at all, according to environment groups. Too little has been done to give the river more space and reduce the potential for damage, the WWF says, while NABU is calling for a financial program to return rivers and their banks to a more natural state.

Climate experts say extreme weather events will occur more frequently as the planet warms.

That means investment in flood protection should not be delayed.

"We have not adapted as well as we could have," says Mojib Latif from the Helmholtz Center for Oceanography in Kiel. "We have to give back a piece of nature. Nature is only reclaiming what was once hers. We must have more flood areas."

Rast, too, sees turning riverbanks back into natural green areas as a necessary measure to adapt to climate change. Even if this were to happen, floods would still occur that society is not equipped to deal with, he says, referring to a major flood that devastated parts of south-western Germany in 1342.

"That kind of thing can happen, as a natural occurrence. We can certainly do a lot to improve the situation. But there is no such thing as total protection against flooding."

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