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After last week's destruction, few people can fail to realize that Europe's weather may be taking a serious turn for the worse. And regardless of the role of global warming, there are measures that can be taken to prevent the same thing happening again.
Bernhard Pelikan, a hydrologist at the Institute for Water Economy in Vienna, says the flooding in Austria was especially severe because of deforestation, intensive agriculture and heavy settlement around the river plains. All of these things, Pelikan argues, stop excess water from draining away and as a result "floods are higher and the water travels faster. You can, of course, say that the amount of rain caused the catastrophe, but it makes a big difference how fast that rain can drain away. We have to give the river more space."
Klement Tockner, an aquatic ecologist at the Swiss Federal Institute of Technology in Zurich, agrees. "With heavy rainfalls, the problem with most rivers is that they are dammed in, so they rise instead of widening." Tockner cites the example of the Tagliamento River in the Friuli-Venezia Giulia region of Italy. The river is 170 km long and up to 2 km wide in places. Although it often floods owing to heavy rainfall, it rarely rises more than 2 m above its average level because it's flanked on either side by meadows and forests that absorb excess water. Problems arise only along a 20-km stretch where the river banks have been built up and the water flow has been regulated by dams. In contrast, the Danube used to be surrounded by 26,000 sq km of meadows that acted as a buffer for flooding waters. Now only 6,000 sq km of meadows remain, the rest having been turned into farmland or housing developments. Last week the Danube rose 6 m above its normal levels in some places.
With about half of Europe's population already living along rivers, it's doubtful that large tracts will be restored to grassland. More and better river management may be the only option. But Tockner says "those measures give people a false sense of security." He argues that a cost-benefit analysis would show that flood protection through natural meadows and forests would be more effective in the long run than apparent gains through agriculture or industry. "The construction and maintenance of dams are extremely expensive," he says. "But environmental protection and human protection are not contradictory. If rivers had more space, people would be protected from floods and there would be a positive ecological effect."
"The brutal reality is that it takes a major flooding event to galvanize societies and governments to take action," says Michael Hulme, director of the Tyndall Institute at the U.K.'s University of East Anglia. "This certainly happened in Britain two years ago [when the country endured widespread flooding during the wettest autumn on record], and I suspect it will now happen in Central Europe."
The residents of Prague have certainly learned their lesson. A barrier similar to the mobile floodwall that was assembled around the Old Town's perimeter had also been planned for the Malá Strana district, which was severely damaged last week. But 18 months of bickering between the city and the various authorities in charge of protecting its architectural and cultural treasures delayed its completion. Now, everyone is committed to getting the job done.
"We are only at the beginning of what we can expect in the future," says Manfred Stock, deputy director of the Potsdam Institute for Climate Impact Research. "Many regions will see an increase in extreme weather, and we will have to adjust to massive changes in our living conditions." If that forecast proves right, then Europe's water wars may be only just beginning