Climate change makes Luxembourg’s floods more severe. Here’s how the country is removing man-made river barriers to manage flooding and improve biodiversity

Luxembourg has always had a problem with flooding.

“I remember the fear on my mother’s face as we walked through flood water going home from kindergarden during the floods in 1993,” says Bruno Alves, attaché to the country’s Ministry of the Environment, Climate and Sustainable Development, who is responsible for managing natural water resources and climate change adaptations.

But the problem has been getting worse.

That’s because of man-made barriers on its rivers and work to narrow or straighten waterways ─ and the effects of climate change. A significant flood in 2021 ruined 6500 homes and caused damage estimated at €125 million.

“It's interesting to look at historical maps, because you immediately understand that something is wrong with the river,” says Alves, who is working on a project to manage Luxembourg flooding by removing sections of barriers on the River Alzette to restore its flood plains. “It’s not as it should be.”

Gradual space reduction for Luxembourg rivers

Landscapes have been altered by humans since after the Ice Age. They have gradually reduced the space available for rivers by channelling them and altering their natural course. So, looking towards a river’s future in a restoration project involves looking back in time at the evolution of the river’s path.

Engineers examined maps dating back to the period of Habsburg rule for drainage works in the 1700s to track changes in the Alzette’s flow and flood plain. They used modern technology to conceive the rewilding project in the valley of an Alzette tributary, the Petrusse, in Luxembourg’s capital, Luxembourg, and along the stretch of river at Steinsel to the north.

“The aim of these projects is to give more space back to the watercourses,” says Alves, “so that in the event of flooding the water can spread out where it does not cause damage to human activities or endanger people's safety.”

Alves and his team also remove man-made obstacles, such as dams or small waterfalls, so that fish can once again migrate freely. Recreating more natural watercourses improves water quality, provides a natural habitat for aquatic plants and animals, and helps to protect towns and villages.

“These projects clearly show that nature-based solutions have multiple benefits for the environment, but also for people," he says.

Loan for Luxembourg river rewilding

The European Investment Bank signed a €9 million loan for the project with the Grand Duchy of Luxembourg in December 2022 to remove man-made barriers and reintroduce a more natural flow to the river. The loan was signed under the Natural Capital Financing Facility, a financial instrument set up by the European Investment Bank and the European Commission under the European Fund for Strategic Investments. The Facility supports projects in biodiversity and climate adaptation through tailored loans and investments, backed by an EU guarantee.

Fragmented rivers

Research by the European Environment Agency shows that most rivers in Europe are impaired by artificial barriers and disconnected from their floodplains. The European Commission estimates that at least 150 000 of the barriers in European rivers are no longer needed. River barrier removal is increasingly seen as a desirable, viable and affordable option.

In the past, free-flowing rivers were thought to add to flood risk, so they were straightened to remove bends, or meanders, and made narrower, with considerable use of concrete. River barriers are now known to worsen flooding and flood damage. Removing barriers will help manage severe flood events that occur more and more often as a result of climate change. It will also restore biodiversity and improve leisure activities such as angling and tourism.

Counting the cost of nature loss

Over 80% of natural habitats within the European Union, such as rivers and forests, have poor or bad conservation status. Healthy ecosystems are essential for securing food production, reducing CO2 emissions and protecting against extreme weather events. Actions that help stop or reverse degradation of habitats, such as removing river barriers, make a crucial contribution to combating climate change and biodiversity loss as well as managing climate change.

Driven by competition for natural resources and to address the impact of climate change, efforts are being made to restore biodiversity in Europe. This involves evaluating its ecosystems and comparing the benefits of habitat restoration against the costs of habitat loss.

But assessing the value of habitats is not straightforward.

“It’s hard to put a value on nature,” says Marco Beroš, a lead engineer working in the European Investment Bank’s water management team. “Economists cannot value biodiversity. When they look at the forest, they value the wood, but they don't value the birds or the little reptiles living there. What's the value of a nightingale?”

Natural capital and ecosystem services

Competition for limited natural resources adds to the complexity. Take water ─ supplies are challenged and declining due to climate change. A relatively small reduction in rainfall can have a large and disproportionate impact on the volume of water available for drinking and sanitation, for crops, livestock and industry, and for creating energy and cooling at energy plants. Not forgetting the water needed for creating and sustaining ecosystems.

Putting an economic value on the combined benefits of ecosystems is a solution to the problem of valuing nature. Natural capital, as it is known, can be evaluated for the direct and indirect contributions ─ or ecosystem services ─ they provide for human wellbeing and quality of life, such as clean air, flood protection, or tourism.

Enlisting support to free rivers

Funding is not the only challenge to rewilding rivers. In fact, only relatively small investments are needed to remove smaller river barriers such as the ones in the plunging Petrusse valley in the centre of Luxembourg and at Steinsel. 

A major hurdle is the amount of time and effort required to gain the support of the large number of stakeholders involved in projects to rewild rivers. These range from national and local authorities to the industries which own the river barriers or use water, as well as local communities that live near or enjoy the rivers.

“Small river barriers have a big impact and there's a potentially big benefit from removing the ones that are obsolete,” says Catherine McSweeney, who works on dam-removal issues at the European Investment Bank. “But there's often a lot of resistance to removing them, because of attachment to a landscape.”

Providing information to stakeholders about the direct contributions from ecosystems, sharing knowledge and showing the benefits of free-flowing rivers such as flood protection, is essential, says Stephen Hart, a European Investment Bank biodiversity expert. “It gives you an entry point to talk about the other stuff, the nature and biodiversity, and people understand it much more. It's probably harder to start with a pure nature project. But starting discussions about a flooding project that will also create more nature is an effective approach.”

The European Investment Bank supported the Luxembourg authorities with advisory services and engaged with civil society to move the project forward locally, as well as providing the investment.

Long-term impact

The removal of several river barriers will have a significant and long-lasting impact on the biodiversity and flood management in Luxembourg. 

“When we do an environmental project and especially when we invest in water projects,” says Alves, “we are also doing something for the next generation.”