Ecologists urge more room for rivers to curb drought and flooding

Ecologists say rivers need more space to help keep water in the landscape and reduce flood risks. Lower Austria has completed 230 restoration projects since 2010, but the effort remains insufficient, experts told ORF.

At Judenau in the Tulln district, the Great Tulln can spread across about 40 metres of riverbed, and in places even wider. A beaver dam slows the water. Thomas Hein, a water ecologist at the University of Natural Resources and Life Sciences, Vienna, described the stretch as an example of how to respond to climate change.

“Having enough water from precipitation is no longer something we can count on every year,” Hein said, adding that it was becoming more important to retain water in the landscape. When rivers have more natural space and water flows more slowly, more can seep into the ground and replenish groundwater for dry periods. Extra space can also reduce flood risks to settlements, he said.

Ecologist Günther Unfer said many rivers were heavily regulated after the Second World War, with the aim of draining water as quickly as possible. That approach was outdated, he said. Fast-flowing water has less contact with groundwater and less chance to seep into it, while narrow channels leave less room during floods and require higher levees.

Restored rivers can also provide refuge for fish during dry spells. Unfer said deeper pools can remain several degrees cooler, offering important shelter for aquatic life during periods of extreme heat.

Hein said more extensive, connected stretches of restored river were needed to improve the relationship between rivers and the surrounding landscape. More than one kilometre of the Great Tulln has been restored near Judenau, and a further 1.5 kilometres is planned near Neulengbach in the St. Pölten district. The river is 40 kilometres long. Hein said the goal should be to restore 20 kilometres over the next 20 years to improve the landscape’s water balance and support groundwater supplies.

Lower Austria’s deputy governor, Stephan Pernkopf, said 20 more projects were currently under construction. A third of the state’s flood-protection projects over the next two years are to include river restoration. About 20 million euros a year has been set aside for the work in the budget for those two years, he said.

Pernkopf said the state needed a combination of conventional flood protection, river restoration and retention basins. Ecologists also called for closer cooperation with landowners, as farmland has expanded closer to waterways over the decades. Farmers could provide strips of land for restoration in exchange for compensation, rent or alternative land, and fields could be deliberately flooded to protect settlements. Hein called for dialogue on the issue.

The Social Democrats in Lower Austria have called for a restoration programme worth 100 million euros a year. The Greens have proposed technical and financial support for municipalities.