Tracking Luxembourg’s water: launch of a monthly hydrological bulletin

From record-breaking rain in September to drought in August, 2025 has already shown how quickly water conditions can shift in Luxembourg, both across regions and over time. To help decision-makers, scientists and citizens stay informed about the evolving state of the country’s water resources, LIST has launched a monthly hydrological bulletin, together with the Administration de la Gestion de l’Eau. Laurent Pfister, Head of the Environmental Sensing and Modelling unit, explains its purpose and what this year’s data reveal so far.

Why is tracking Luxembourg’s rivers more important than ever?

River discharge is one of the most sensitive indicators of climate variability. Over recent decades, Luxembourg has experienced both more intense rainfall and longer dry spells, signalling that its hydrological systems are under increasing pressure.

With this hydrological bulletin, we translate decades of monitoring into a clear, accessible overview of water trends. Each month, we summarize rainfall and streamflow data from long-term monitoring stations, giving context and clarity to decision-makers, researchers and citizens seeking to understand how local river basins are responding to climate shifts.

How can the hydrological bulletin support decision-making?

The bulletin is meant to build a shared understanding of Luxembourg’s water resources. It’s a bridge between data and decision-making. Whether in water management, land planning or environmental research, access to continuous and reliable information is key.

The hydrological bulletin helps anticipate events rather than react to them. Over the long term, we hope this knowledge will help support the country’s resilience, from preparing for floods to managing drought risks more effectively.

What does the 2025 data tell us about current trends?

While January was particularly wet, subsequent rainfall was largely below average from spring into summer. In contrast, September rainfall was particularly abundant, with monthly precipitation locally exceeding 200 mm. Notably, in the Mersch area, record precipitation totals of around 180 mm were recorded between September 8 and 9, 2025.

After reaching high levels in January, river discharge remained (sometimes significantly) below the long-term average values between February and August 2025. The heavy rains in September 2025 led to a noticeable increase in the monthly discharge (higher than the values observed during the long-term reference periods) in all rivers. However, considering these exceptional rainfall totals, the course of events in September could have been catastrophic if antecedent conditions had been wetter at the end of summer.

Explore the first issue: English version // French version

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