Flooding in Western Europe: what happened in July 2021?
29 July 2021
From Monday 12 to Thursday 15 July 2021, an area of Western Europe that included parts of Germany, Belgium and the Netherlands experienced an extreme rainfall event that led to severe flooding that had catastrophic consequences, causing the death of more than 190 people (at the time of publishing) and billions of Euros in damage to property and infrastructure. In many places over 15 cm of rain fell in 24 hours or less, which is an extraordinary amount in a region that usually receives the same amount of rain over two months. Despite the many improvements in predictions and the associated warning of an extreme event from weather and hydrological forecasting agencies, the speed and magnitude of these floods caught many people by surprise.
The interdisciplinary nature of flood management
Flooding in Europe is a persistent and common problem and researchers have been working for decades with governments at all levels to try and prevent what happened earlier this month in Western Europe. These efforts require a truly interdisciplinary approach and often bring together atmospheric, climate, ocean, hydrological, geomorphology and natural hazards sciences, among others . Understanding the interactions between the many Earth system components is crucial, as is working with researchers from the Social Sciences, Economics and the Humanities to connect this understanding to the behaviours and needs of people who live in flood prone areas. “The study of dynamic interactions and feedbacks between water and people is at the heart of social-ecological systems research in hydrology’, EGU Hydrological Sciences Division President, Maria-Helena Ramos explains. ‘The most recent flood disaster in Europe points to a combination of factors, from extraordinary amounts of rain falling over saturated soils from previous rainfall, to flooding enhanced by the mountainous topography, including flash floods in upper reaches of the rivers and in narrow valleys.”
But obviously rivers alone were not the only factor in the recent disaster. Images of houses collapsing, streets being torn away and the formation of sinkholes were captured and shared by residents in all affected countries, which are all processes studied by experts in geomorphology. “Floods are not only comprised of water, they move significant volumes of sediments such as gravels, sand and mud”, EGU Geomorphology Division President Dan Parsons says, “Fast flowing torrents of water are able to mobilise and erode river beds banks and reshape the landscape. They also carry significant volumes of debris which can destroy homes and infrastructure, as we saw with these recent events.”
It is common for natural hazards such as flooding to be connected to other hazards, such as landslides or storm surges, in fact one branch of research in natural hazards looks specifically at multi-hazards; those types of hazards that are frequently combined with others. EGU Natural Hazards Division President Ira Didenkulova describes why hazards rarely occur on their own.
“Natural hazards are interdisciplinary by nature. Often extreme events of different types occur simultaneously, cascadingly or cumulatively over time. Floods may trigger landslides, wildfires and environmental and ecological disasters (for example, the Fukushima accident). The latter is often related to human activity and is a result of building critical infrastructure in a flood-prone zone. This is the idea behind the ‘NoNaturalDisasters’ movement. Societal and cultural influences are also important. Different places experience hazards differently because of different cultural traditions for societal organization and behaviour during extreme events, which also impacts hazard and risk assessment, and the corresponding mitigation strategies.”
Flooding and climate change
One of the most significant connections that people have made in the aftermath of the tragedy is the influence of climate change on the severity of the flooding. Climate change leads to an increase in the frequency and magnitude of extreme weather events, much like the extreme rainfall event that instigated the flooding, but the influence of climate change goes far beyond increasing extreme weather events
“The observed intensification of rainfall in Central Europe is one of indices for the climate crisis we are facing,” EGU Climate: Past, Present and Future Division President Irka Hajdas explains. “These dramatic flooding events in one part of Europe have been accompanied by the extreme heat wave experienced in other parts of Europe. Outside Europe, several places are suffering drought that results in hunger and population displacement such as is happening in Madagascar.”
“We are now living a new normal,” EGU Atmospheric Sciences Division President Athanasios Nenes explains. “One that is ever-changing and characterized by extreme heat, wildfires and record-setting storms.”
Flooding and policy in Europe
European, national, and local governments have a large amount of control over the types of policies and measures put in place to mitigate the environmental and social impacts of human induced climate change, like the recent floods. It is important that those creating and implementing the policies impacting a region’s resilience understand the potential consequences of any action or inaction and use this to guide their decision-making.
“As a scientific community, it’s our duty to ensure that the relevant research is communicated effectively and can be used by policymakers when they’re considering different policy options,” says EGU’s Policy Officer Chloe Hill “and there are many ways that scientists can get involved and share their research with policy makers directly.”
So what can you, as a researcher, do to help policymakers? One of the formal processes that enable scientists to share their research with European policymakers is the European Commission’s Consultations, which often mark the beginning of the European legislation process. Scientists can even register with the European Union as an external expert to assist in the evaluation of grant applications, projects, and to provide opinions and advice in specific cases. Some Commission Directorate Generals have their own databases of experts that are open to scientists wishing to contribute to more specific issues, such as Scientific Committees or hearings.
Research on floods is particularly relevant for a wide-range of policy areas, as decision-makers need to consider the impact that any new policy could have on a region’s resilience to floods and other natural hazards, though the type of advice and the mechanisms for sharing expertise will vary in different European regions. It’s also worth remembering that policymakers within each EU member state and municipality also often require direct scientific advice.
However, for many people connected to this event or concerned for their own safety, future plans for mitigating the impacts of human-induced climate change are too far removed from their day to day lives. For those impacted by the flooding, recovery will be a long, slow and difficult process, and many of those will also have lost loved ones, friends or colleagues to the disaster. EGU President Helen Glaves says, “EGU would like to convey our deepest condolences to those who have lost family, friends or colleagues, and we also send a message of support to those who have been seriously impacted by this catastrophic flooding event.
We are seeing an increasing frequency and intensity of these extreme events that is triggered by our rapidly changing climate. We as a society must ensure we are better prepared to respond to these crises, and take strong and positive actions to mitigate their impacts. Many of EGU’s members are directly engaged in scientific research that provides expertise and insights into the global climate crisis, but we all must play a role in preventing further escalation of this situation before it leads to yet more catastrophic events, such as those recently experienced across a large area of western Europe.”
If you are concerned about your flood risk, there are several resources you can use to find more information, including:
- Copernicus Emergency Management Service page for the July flooding in Western Europe
- Safer Places flood risk mapping resource
- European Commission handbook on good practice on flood mapping in Europe
- European Flood Awareness System
- World Health Organization’s public health advice for flooding in Europe