Climate change also affects precipitation and thus water availability. IN many countries there is already a water shortage. But what about us? Is water also becoming scarce in Germany? And how can water be used more sustainably in the future – also in this country? Scientists at the Research Center Jülich are researching this. In the interview they explain where the problems lie and what could be done.
The climate is changing even here in Germany: In spring and summer, the rain needed for plants is increasingly missing and it is becoming drier. As a result, droughts and crop losses have increased in recent years, even in our actually water-rich country. When precipitation does fall, it increasingly occurs as heavy rain – and sometimes leads to catastrophic flash floods and floods. This presents new challenges to our use of water resources. Stefan Kollet and Frank Herrmann from the Research Center Jülich are researching how Germany could best cope with this. They answer questions on the topic on the occasion of World Water Day on March 22nd.
Many people think: It rains often enough in Germany. Why are researchers still talking about increasing water shortages?
Frank Herrmann: Water shortages can also occur in Germany at short notice – for example during a long summer drought. This was the case in some parts of Germany in 2018, for example. On some large rivers, shipping traffic had to be stopped because the water levels were too low. This is also a manifestation of water shortage. In times like these, the demand for water in other areas also increases: farmers have to irrigate their fields, cities need more drinking water and private households also use more water. This can lead to water shortages in individual regions.
The federal government stated in the “National Water Strategy” that there should be a set of rules for prioritizing use in such cases. Science is currently working intensively on recommendations for action and so-called guidelines for prioritization. This is also a recurring topic at national specialist conferences.
International studies now warn of global overuse of water resources. How do you classify 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 areas of the world and especially where water is used for agriculture and overexploited. In Germany there are certainly regions in which water can become scarce locally and regionally at times. However, the availability here varies greatly depending on the region and time of year: While there is drought in some areas or years, there is sufficient or even too much water in other places or at other times. In my opinion, we definitely cannot speak of water bankruptcy in Germany. In fact, the future will be about securing our water security against the background of climate change, increasing extreme events and needs. This is a big challenge.
What changes will we have to prepare for in the future? In which areas are water shortages or usage conflicts particularly relevant?
Herrmann: Most scientists now agree that we are facing a complex interplay of climate change, increasing water use and very different regional conditions. Drought phases may occur more frequently and be more severe in the future. This will affect many sectors, such as agriculture, energy production, industry and public water supply. However, it is difficult to predict how severely individual regions will be affected. That’s why we need to be prepared nationwide.
To this end, science has established the concept of so-called “stress tests” for water systems. Cross-sector scenarios are developed that occur if a drought period lasts for a longer period of time. In such scenarios, possible usage conflicts can be identified and prevented from a planning perspective. For example, we analyze how much water is still available in rivers and groundwater, how high the needs of various users are and which use would have to be restricted in an emergency. On this basis, measures for drought management can be developed.
The so-called resilience of the water supply plays an important role, i.e. the question of how robust a system remains even under difficult conditions. These include sufficiently large water storage facilities such as dams, stable supply systems for drinking water or sustainable use of groundwater reserves. For example, if a small river has hardly any water during a drought, no more water can be taken from it for field irrigation.
What role do the different interests of agriculture, industry, cities and nature conservation play in water management?
Herrmann: These sectors depend in many ways on the so-called water supply – i.e. on the amount of water that is actually available in a region, for example in rivers, lakes, soils and groundwater. At the same time, many users are connected to one another via common water supply systems, such as drinking water pipes, aquifers or dams. When water becomes scarce, conflicts of use can arise. In this case, there is a legal priority for public water supply, especially because it ensures our drinking water supply.
In the long term, however, the goal of sustainable and precautionary water management is to balance the needs and interests of all users as well as possible. It is therefore necessary to analyze the water requirements of the sectors and the water supply together in so-called hydro-economic model systems. These models combine information about water availability, i.e. precipitation or groundwater, and water requirements of different users. This makes it possible to simulate how different decisions affect the entire water system.
Such models also play an important role in the “Solution Lab Rur-Erft”, or SLRE for short, project. There you will develop a hydro-economic digital twin of the region. What does that mean specifically?
Kollet: In SLRE we bring together various very advanced model systems that are currently being used in the area of climate-water-nature-humanity. Some of these models are specialized on individual questions. Hydrological models calculate, for example, how precipitation is distributed in the ground and how much water then seeps into the groundwater. Others analyze how much irrigation water is necessary for specific crops or how flood waves build up and spread in river systems. There are also models that look at economic aspects, such as the water requirements of agriculture and industry. These models each provide valuable data and insights – but only for their specific area of application.
We want to connect all of these model systems, which is currently still a major challenge. This will then create a digital twin of the region. This means we can then simulate how the entire water system develops under different conditions – for example during long periods of drought or heavy rain. And we want to use new possibilities of artificial intelligence to prepare this data and findings even better in the future and thus make them available for water management in practice.
Herrmann: From our perspective, a broad mix of different measures will be needed to sustainably secure our water resources. This includes more efficient irrigation in agriculture, better storage of water in dams and soils, sustainable use of groundwater and, in particular, more coordinated, nature-based water management between different users. In order for such decisions to be made well-founded, we need reliable data about water availability and demand. Further improving this database is a central research task. Only if we understand the processes and uncertainties that influence the quantity and quality of our water resources can we use them fairly and sustainably in the long term.
Source: Research Center Jülich