20 March 2026
Increasingly dry summers, alongside a rise in heavy rainfall events, are presenting us with new challenges in our management of water resources. Rising demand for water and intensive water use are exacerbating the situation. The latest UN report on "Global Water Bankruptcy" warns that many water systems worldwide are already being overexploited.
Could water become scarce in Germany too? And how can water be used more sustainably in future - including in Germany? Researchers at Forschungszentrum Jülich are working to better understand water and promote its sustainable use. We spoke to Prof. Dr. Stefan Kollet and Dr. Frank Herrmann from the Institute of Bio- and Geosciences - Agrosphere about these issues.
Many people think it rains often enough here in Germany. So why do researchers still speak of increasing water scarcity?
Frank Herrmann: Water shortages can also occur in Germany, even if only temporarily - for example, during a prolonged summer drought. This was the case in parts of Germany in 2018, for instance. In some cases, shipping on major rivers had to be suspended because water levels were too low. That, too, is a manifestation of water scarcity. At such times, demand for water naturally rises in other sectors as well: farmers need to irrigate their fields, cities require more drinking water, and households use more water too. This can lead to water shortages in certain regions. In its "National Water Strategy", the German Federal Government has stated that there should be a set of rules for prioritizing water use in such cases. Scientists are currently working intensively on recommendations and guidelines for prioritization. This topic is also regularly discussed at national specialist conferences.
International studies now warn of a global overuse of water resources. How do you assess this development from a scientific perspective - and what does it mean for Germany?
Stefan Kollet: A new UN report speaks of "water bankruptcy" in many parts of the world, particularly where water is used and overused for agricultural purposes. In Germany, there are certainly regions where water can become scarce locally and regionally at times. However, availability here varies greatly depending on the region and the season. Whilst some areas or years experience drought, there is sufficient or even too much water elsewhere or at other times. In my opinion, we definitely cannot speak of water bankruptcy in Germany. In fact, the challenge going forward will be to safeguard our water security in the face of climate change, increasing extreme events, and rising demand. That is a major task.
What changes do we need to prepare for in the future? In which areas will water scarcity or conflicts over water use be particularly relevant?
Frank Herrmann: Most scientists now agree that we face a complicated mix of climate change, rising water use, and highly variable regional conditions. Droughts are likely to occur more frequently and be more severe in future. This will affect many sectors, such as agriculture, energy production, industry, and public water supply. However, it is difficult to predict exactly how severely individual regions will be affected. That is why we need to be prepared nationwide. For instance, scientists have developed the concept of "stress tests" for water systems. These involve creating cross-sectoral scenarios for what happens if a drought were to persist over a prolonged period. In such scenarios, potential conflicts over water use can be identified and plans made to prevent them. For example, we analyse how much water is still available in rivers and groundwater, the demand of various users, and which types of water use would need to be restricted in an emergency.
On this basis, measures for drought management can be developed. A key factor is the resilience of the water supply - in other words, how robust a system remains under difficult conditions. This includes sufficiently large water reservoirs such as dams, stable drinking water supply systems, and the sustainable use of groundwater reserves. For instance, if a small stream has very little water during a drought, no water should be drawn from it for field irrigation.
What role do the differing interests of agriculture, industry, cities, and nature conservation play in water management?
Frank Herrmann: These sectors depend in many ways on water availability - the amount of water actually available in a region, for example in rivers, lakes, soil, and groundwater. At the same time, many users are connected through shared water supply systems, such as drinking water pipelines, aquifers, or reservoirs. When water becomes scarce, conflicts over its use can therefore arise. In such cases, public water supply has legal priority, primarily to ensure our drinking water supply. In the long term, however, the aim of sustainable and precautionary water management is to balance the needs and interests of all users as effectively as possible. It is therefore necessary to analyse the water requirements of different sectors together with water availability using hydro-economic modelling systems. These models combine information on water availability - such as precipitation or groundwater - with the water demands of various users. This allows us to simulate how different decisions might affect the entire water system.
Such models also play an important role in the "Solution Lab Rur Erft" (SLRE) project. Through this project, you are developing a hydro-economic digital twin of the region. What does this look like in practice?
Stefan Kollet: In SLRE, which is part of the Helmholtz Association's research initiative "Water safety and security for people and the environment", we bring together a number of highly advanced model systems that are already being applied in the interaction between climate, water, nature, and people. Some of these models are specialized for specific issues.
Hydrological models, for example, calculate how rainfall is distributed in the soil and how much water seeps into the groundwater. Others analyse how much irrigation water is needed for certain crops or how flood waves develop and spread through river systems. In addition, there are models that consider economic aspects, such as the water requirements of agriculture and industry. Each of these models provides valuable data and insights - but only for their specific area of application.
Our aim is to integrate all these modelling systems, which is currently a major challenge. The goal is to create a digital twin of the region. This would allow us to simulate how the entire water system develops under various conditions - such as during prolonged droughts or heavy rainfall. We also want to make use of new possibilities offered by artificial intelligence to process these data and insights even more effectively in future, making them available for practical water management. This is where our "Interactive Solution Room" comes into play.
What is the Interactive Solution Room, and how does this approach help make better decisions about water management?
Stefan Kollet: In the Interactive Solution Room, experts come together who are involved in managing a region's water resources in different ways - for example from public authorities, the water industry, agriculture, and science. Based on simulations from the digital twin and a wide range of measurement data, specific scenarios will be explored there, such as prolonged periods of drought or rising water demand in certain regions. The new approach allows participants to intervene interactively in these scenarios This enables them to test how different decisions affect the development of the water situation.
The participants can work together to consider which measures are sensible and effective under specific conditions, and in doing so develop a broad understanding of how the water system as a whole reacts. That is our goal. However, our experience in recent years has shown that this is not always so straightforward. The differing interests of stakeholders and the uncertainties in the processes naturally play a role and must be taken seriously.
Which measures do you consider particularly important in the long term to secure water resources sustainably - and what role can research play in this?
Frank Herrmann: In our view, a broad mix of measures will be needed to secure our water resources sustainably. This includes more efficient irrigation in agriculture, better water storage in reservoirs and soils, the sustainable use of groundwater, and, above all, a more coordinated, nature-based water management approach between different users. To ensure that such decisions can be made on a sound basis, we need reliable data on water availability and water demand. Improving this data basis is a key task for research. Only by understanding the processes and uncertainties that influence the quantity and quality of our water resources can we use them fairly and sustainably in the long ter
