Adaptation to climate change
The race for water
Michael Krautblatter goes ahead into the Kammstollen tunnel, a cable drum on his back. Running deep within the Zugspitze mountain, the tunnel was originally built for skiers almost a century ago, and is now part of . After first passing through utility ducts, the path reaches a bend and we can only progress by crouching. The tunnel walls here are clothed in ice crystals that sparkle in the light from our head torches. But how much longer will they be here?
Professor Krautblatter unrolls the cable and clips it to one of the electrodes that are screwed into every few meters of the rockface. The geoscientist and his team from the come here to check the condition of the permafrost鈥攖he permanently frozen rock. They use electrical resistivity tomography (ERT) to collect information about the expansion of this permafrost almost 100 meters below the peak of the Zugspitze. 40 thermometers set into the rock simultaneously measure its core temperature. In this area, it has risen by half a degree to 鈥�0.7 degree Celsius since 2007. The permafrost in the limestone of the Zugspitze begins to thaw above the equilibrium freezing point of 鈥� 0.5 degree Celsius.
Permafrost acts as an adhesive and fills tiny cracks and crevices in the rock, stabilizing the mountains. Without this 鈥渃ement,鈥� the Alps will start to crumble and rockslides, rock falls, and mudflows will become increasingly frequent, as seen on the Fluchthorn in 2023. As Krautblatter explains, lower snowfalls and higher temperatures also cause greater volumes of water to flow from the mountain peaks to the rivers in the spring snowmelt, a phenomenon that has been observed over decades. However, this is set to change within the foreseeable future. When the glaciers and permafrost shrink, the water reservoirs in the Alps will dwindle with them. Because of this, rivers will carry less and less water in hot and dry years, the very times when the need for water is at its most urgent, for example, for agricultural irrigation. 鈥淭he Alps are warming twice as fast as the global average. It鈥檚 like a time machine showing us the future,鈥� says Krautblatter.
Given this, one aim of his research is to develop geophysical and chemical methods that can distinguish and quantify glacial and permafrost meltwater, and thus enable him to more accurately estimate the levels still remaining in these frozen reservoirs in the Northern Alps. 鈥淭his is the only way for us to predict how much water will flow down from the mountains in the future, and forecast what that will mean for the rivers over the next 30 to 40 years,鈥� says Krautblatter. 鈥淧ermafrost water will be available for longer in summer than glacier meltwater.鈥�
With less water, but more stones and sediment washed into the valleys, how will that change the rivers鈥� flow rates and affect the habitats of fish and other water wildlife? What impact will this disrupted water cycle have on agriculture, hydropower, and public water supplies? 鈥淭hese are questions that require interdisciplinary expertise to provide the answers,鈥� advises Krautblatter.
A group of researchers in science and engineering, life sciences, economics, and social sciences has formed the with precisely this aim in mind. The topics covered by the cluster span water science, optimization of hydroelectric power stations, and the importance of water for ecosystems and agriculture, but also extend to analyses of international climate policies. More than 15 different chairs are involved, working together on devising solutions for resilient water systems and rapid adaptation strategies to combat the impacts of climate change. Krautblatter warns that it may take at least ten years before concrete measures can be implemented, 鈥渟o we need to start right now.鈥�
Instability is the new normal
鈥淭ime is running out for us,鈥� agrees Prof. J枚rg Drewes from his office at TUM鈥檚 Garching campus. The points out, 鈥淔or decades, we have been able to base the planning and operation of our water infrastructures on long-term empirical data for aspects such as precipitation patterns, water runoff, and natural groundwater recharge. But this assumption is not valid anymore.鈥� Extreme events that used to occur once a century are now occurring ten times more frequently. As Drewes puts it: 鈥淚nstability is the new normal.鈥�
The expert on water systems co-chairs the German Advisory Council on Global Change (WBGU) and advises the German government. In January, he and a group of researchers from various universities published the WBGU flagship report The council warns that the global water cycle is changing at an accelerated pace, resulting in longer and more frequent periods of flooding and drought, water shortages in urban areas, and rising water pollution鈥攖o name just a few of the consequences. 鈥淭hese threats are by no means confined to specific regions; they represent patterns on a global scale,鈥� says Drewes. Hence, international cooperation over climate change must be equally widespread, 鈥渢o maintain an appropriate distance from the limits of controllability,鈥� as the report states. The goal must be to establish a climate-resilient water management with a long-term perspective that can respond flexibly to change. In J枚rg Drewes鈥� view, the role of science is to provide fast, robust data as a basis for developing and supporting adaptation strategies while ensuring affected and interested stakeholders are actively involved.
The value of water
In Upper Franconia, around 300 kilometers north of the Zugspitze, TUM researchers are investigating ways of putting those aims into practice. The largely agricultural region around the Upper Main river has some of the lowest rainfall levels in Bavaria. Climate change, accompanied by increasingly frequent torrential rains and flooding, is exacerbating the situation.
When water supplies become scarcer and more unstable, what does that mean for the sectors that depend on them? For households, industry, power generation, and agriculture, to say nothing of ecosystems such as riverscapes, grassland, and forests? This is one of the topics under investigation by Dr. Maria Vrachioli, a senior researcher at the and coordinator of the European research project , which includes a case study on the Upper Main. 鈥淥ur goal is to develop sustainable water management strategies and structures for everyone,鈥� she affirms.
One option that can ensure the increasingly scarce resource of water is efficiently distributed and avoid conflict is to place a price on it. 鈥淭o date, river or groundwater has been used for irrigation free of charge in Bavaria. We are investigating whether it is possible to place a price on irrigation water, in order to achieve more sustainable use while ensuring food crop cultivation remains profitable,鈥� says the economist. This can only succeed by bringing all stakeholders together, from government and local policymakers to professional associations and grassroots initiatives: 鈥淥ur aim is to include everyone in the debate and convince them that new political and business approaches are required alongside new technological solutions.鈥�
The vital data for the Upper Main case study is provided by a team at the . A web of colored lines fills Dr. Jingshui Huang鈥檚 computer screen: blue for river water, green for wells, and red for water consumption by households, agriculture, and industry. What happens when drought necessitates more frequent irrigation? What impact does reforesting have on the regional water balance? To answer these and similar questions, the researchers are using the database to develop an array of scenarios for RETOUCH Nexus. This data then informs decision-making by the local responsible parties.
But data of this kind is also sought after outside Germany as climate change and economic and population growth cause water shortages in many regions around the world. An international team in the EU project is thus working on a decision support system (DSS) for the border region between Kyrgyzstan and Uzbekistan. Here too, data on water availability and consumption is collected and integrated. 鈥淲ith our system, we provide in-depth knowledge about how the water resources in the region will develop,鈥� says Jingshui Huang, who is coordinating the project. 鈥淚n this way, we can help decision-makers to respond better to challenges and develop sustainable strategies across borders.鈥� The aim is to avoid conflicts and reduce water stress for communities, the economy, and the environment.
Ways out of the crisis
鈥淚n the past, the focus has often been on how to divert excess water as fast as possible,鈥� says Markus Disse, Professor of Hydrology and River Basin Management. Given this, there is already ample research data on flood protection technologies such as dams and polders. 鈥淭o combat heat and dryness more effectively, we are now working on solutions that provide more efficient local water retention,鈥� he says. Disse is working on decentralized, near-natural measures for restoring soil water retention and improving groundwater recharge. The key here is 鈥済reen water鈥濃�攊n other words, naturally occurring soil water and rain water, which is absorbed by plants and evaporates.
One of the Chair鈥檚 projects, for example, examines ways of using existing drainage ditches as interim storage capacity to take up excess surface water runoff during heavy rainfall, and then return the water to the land in dry periods. Moors and bogs as natural temporary storage have likewise been a focus of Disse and his team. A further collaboration project with researchers from the is examining the ecosystem of the River Isar and its riparian forests. The team is investigating how water availability impacts on plant growth, and how the vegetation in turn affects the water cycle. 鈥淚t鈥檚 the cross-disciplinary nature of the work that makes the research environment at TUM so exciting,鈥� says Disse.
Back at the Zugspitze, Michael Krautblatter shoulders his cable drum once more and heads back to daylight. In the cable car down to the valley, he reminisces about seeing concerned faces among his student audience at a conference. Instead of holding the third talk on the consequences of climate change as planned, he spontaneously decided to outline the available possibilities of rapid adaptation. 鈥淏y focusing on solutions in this way, we can encourage young people to play a part in shaping their future. If we鈥檙e smart about it, we then have a good chance of preserving an environment that is worth living in.鈥�
- As TUM鈥檚 focus program for water research, the coordinates research and teaching activities on water-related issues. The cross-disciplinary program involves over 15 chairs engaged in developing future-facing solutions for establishing resilient water systems.
This article was published in the 02/2025 issue of the new TUM Magazine.
