Walls — and neighbors — protect against Danube flooding | Environment| All topics from climate change to conservation | DW | 08.05.2018
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Environment

Walls — and neighbors — protect against Danube flooding

Strong community ties can keep people safe during catastrophes, say experts. So what can the residents of a flood-prone Austrian town teach us about facing extreme weather in the age of climate change?

Herwig Türk was 11 when he moved with his parents to Melk, Austria in the spring of 1975. His earliest memories include the aftermath of a flood. When he saw the thick muck blocking the door of his family's new house, he questioned his mother's choice of new home.

"I remember thinking, why would anyone want to live in a place where the water rises up," he told DW. "But 43 years later I'm still here."

In that time, the town has seen repeated floods, including two "once-in-a-century" events just 11 years apart, in 2002 and 2013. A cluster of extreme floods locally can be a statistical coincidence. But there is a global trend of increasing weather extremes.

Read more: Climate change and extreme weather: Science is proving the link

The story of how Türk and his neighborhood have adapted to flooding offers lessons for other communities preparing for future extremes. A grassroots approach that strengthens community bonds and improves trust and communication is one of the most effective ways to climate-proof communities, according to experts.

Shifting climate

Photo: A man points to a wall in Melk, Austria (Source: Bob Berwyn)

Fischergasse resident Herwig Türk points up to a marker he installed showing the peak of the 2002 Danube flood near the entrance to his home

In Europe, climate change may be altering the behavior of a characteristic storm track that brings Mediterranean and Atlantic moisture to the Danube River drainage, says Günter Plöschl, a hydrologist at the Vienna Technical University.

"The events have not become more frequent, but the heavy rainfall intensity during the events has increased," Plöschl told DW.

The flood of 2002 came during such a weather pattern and swamped huge swaths of central Europe, including the Danube Valley. At Passau, on the German-Austrian border, it was a 500-year flood, and in Melk, Türk's only escape was through an upper story window in a boat.

Read more: Rethinking Germany's Rivers

A similar weather pattern in 2005 triggered flooding along the Danube as forest fires raged in Portugal at the same time. Between the two floods, a widespread extreme heatwave killed about 70,000 people in 2003.

At that time, climate experts started warning that the biggest threat from global warming might not be the steady rise of global temperatures but unexpected life-threatening extremes — a cautionary chorus that has grown louder in the past 10 years.

Where does the water go?

Directly beneath Melk's mighty Baroque abbey, a modernist steel sculpture documents the flood levels in human times, its design forcing people to look up and imagine 4, 7 or 10 meters (13-33 feet) of water overhead. The memorial sits directly atop a massive stormwater pumping station, built as an adaptive measure after the 2002 flood.

Photo: Flood waters on a street in Melk, Austria (Source: Herwig Türk)

Pumps struggle to keep up with floodwaters in Melk during the 2013 Danube flood

Türk was able to move most of his valuables from the lower floor of his house before that flood. The forecasts predicted the danger days in advance. In the immediate aftermath, he focused on helping his neighbors rebuild.

"We thought it (the water) would come here first, because this is the lowest spot in Melk," said Türk, referring to his street, the Fischergasse. "But water moves in mysterious ways."

Melk began working on a community protection plan after the 2002 flood, including a flood wall. The proliferation of such measures led to concerns about downstream flooding, but hydrologist Plöschl said the volume of water that's diverted by defensive structures is so small that it doesn't increase flooding elsewhere, though it does speed up the flow.

Read more: In the eye of the firestorm: Surviving Australia's most extreme bushfire

Social resilience

Through his work with flood survivors, Türk recognized that the community needed more than just a physical wall, so he started building a grassroots resiliency organization that helps both current residents and new arrivals prepare for the impacts of flooding.

Photo: Residents in the town of Melk, Austria (Source: Herwig Türk)

Each year, a grassroots flood resilience group in Melk, Austria holds a street festival in the Fischergasse, with proceeds benefiting a local cause, including flood survivors

The neighborhood group has grown into a formal organization, the Interessengemeinschaft Hochwasserschutz (flood protection interest group), which holds a street festival each year to celebrate the resiliency of the Fischergasse. The proceeds benefit a different cause each year, including flood survivors.

Read more: Japan marks 7th anniversary of tsunami and Fukushima nuclear disaster

The social aspect of community resiliency can be a critical factor when a catastrophe strikes.

Last year, researchers published a study comparing villages in Japan that suffered disaster during the 2011 tsunami and earthquake. They found that survival rates were significantly higher in communities with strong social ties and high levels of trust and interaction.

Read more: Extreme weather: A Bavarian village fights the floods

There's also an important role for community groups in shaping risk management, says Maarten van Aalst, director of the Red Cross Red Crescent Climate Centre.

"Better risk management may require difficult choices, and those choices need to be supported by the communities affected, both by the potential flood itself, and by the interventions, such as changes in land use, construction of protective infrastructure or green solutions with similar effects," van Aalst told DW. "These sort of local initiatives are critical to make those links."

In Melk, the community discussed the new flood wall for years, including potential new risks if the structure were to fail, says Melk town council member and lifelong volunteer firefighter, Patrick Strobl.

When the floods return

Photo: A resident of the town of Melk at a computer (Source: Bob Berwyn)

Melk resident and flood survivor Herwig Türk shows photos of historic floods in his neighborhood near the Danube

Houses like Türk's in the Fischergasse have survived the rise and fall of Danube waters for centuries. Still, they've never been exposed to the type of forces that would be unleashed if the flood wall collapsed, releasing a deluge of water into the neighborhood all at once, said Strobl, and as a result, he has worked to boost warning efforts and evacuation plans.

Construction of the flood wall started in the spring of 2013, so Türk thought he was safe from the water. But in the middle of the project, an unusually stagnant weather pattern that appears to be linked to global warming developed. It pumped record amounts of rain into the Danube region and the river rose again, swamping the construction zone, as well as Türk's house.

The wall is finished, but will it hold during the next flood? Only time will tell.

"When it gets as extreme as it was in 2013, you really start questioning whether you should stay. The thick walls of these houses take at least 10 years to dry out completely," said Türk. "The next flood will test it (the flood wall). We'll see. If it's a thousand-year flood, the wall probably won't be enough."

 

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