Megafloods: Revealing the Past, Protecting the Future

By their very nature, megafloods are rare and catastrophic events, leaving scientists with limited knowledge about their triggers and frequency. To bridge this knowledge gap, researchers at the Luxembourg Institute of Science and Technology (LIST) dedicate significant time to collecting historical data, scouring Europe for records of past megafloods. This enriched database enhances our understanding of these powerful natural events, providing robust statistics that are essential for future predictions.

Over the past 25 years, LIST has established an exceptional monitoring network encompassing meteorological stations and river monitoring sites. Luxembourg, despite its small size, plays a pivotal role in this network. The country's diverse geology, varied land use, and homogeneous climate create a natural testbed for studying how different physiographical settings influence hydrological responses. This unique combination of factors allows researchers to gather invaluable data and insights.

Looking ahead, researchers rely on mathematical models to forecast future events. These models simplify reality, often assuming a stationary world that doesn’t change. However, this assumption is flawed, especially as we push models beyond their design limits to project future scenarios. With only 100 to 150 years of meteorological and hydrological observations, our understanding of past river behavior is limited.

To overcome this, LIST scientists turn to natural archives such as tree rings and freshwater mussels, which act as recorders of past environmental conditions. By analyzing these natural records, researchers can reconstruct historical events, gaining valuable insights into the past functioning of rivers. This knowledge is crucial for improving our future predictions, helping us better understand and prepare for the impact of megafloods.

A study, published in Nature Geoscience and led by LIST, analyzed historical flood data across Europe, revealing that megafloods haven’t changed significantly over time. By examining over 8,000 gauging stations spanning two centuries, the research proposes an international approach to predict floods by categorizing rivers based on shared characteristics. This method, using data from similar basins, could anticipate disasters like the 2021 Rhine basin flood.

LIST’s researchers emphasize the need for cross-border cooperation to enhance flood prevention, urging a shift from national to continental risk assessments. Future plans involve using accumulated knowledge to project river responses to climate change in Luxembourg and delving into natural archives for millennia-spanning insights. LIST’s approach aims for informed decisions in infrastructure protection amidst evolving environmental challenges.

This article is part of our summer campaign showcasing some of the stories from the LIST Annual Report 2023.