What is often abundantly available in one place is painfully missed in another. Climate change confronts Germany with a new situation: the valuable resource water—which had been available in sufficient quantities—is increasingly becoming a scarce resource in some regions.
Fred Fokko Hattermann, Climate Researcher at the Potsdam Institute for Climate Impact Research (PIK) reports: “In recent years, we have been getting more and more feedback from water management companies that wells dried up. That did not happen in the past.”
Lower Saxony's Environment Minister Olaf Lies also sees the first signs of a water crisis. He warns against pessimism and advocates a comprehensive water quantity management throughout Lower Saxony. In order to develop concepts, the budget of his ministry has almost three million euros available for this purpose.
The analysis of the German Federal Environmental Foundation (DBU) is similar. Secretary General Alexander Bonde calls for a paradigm shift and emphasizes: “The sustained drought of recent years makes it necessary to keep the water in the landscape and to give running waters sufficient space.” Water management needs adjustments in times of heat, drought, and heavy rain. “Regional concepts developed by the concerned stakeholders from authorities, water management, agriculture and nature conservation are particularly useful,” says Bonde.
“In order to make use of moors, meadows and wetlands, in the past, areas were drained via ditches and drains as well as rivers and streams were straightened—and are still today,” adds DBU department head Dr. Maximilian Hempel. As a result, the water runs off more quickly, leaving only a few reserves in the landscape. “If it doesn't rain for a long time, as in the summer months of the last few years, more and more areas are drying up and the groundwater level is sinking," says the DBU expert responsible for environmental research and nature conservation. Over the past two years, the drought monitor of the Helmholtz Centre for Environmental Research (Leipzig) has repeatedly shown phases of extreme to extraordinary drought of the entire soil for many regions of Germany.
What are suitable countermeasures? A project of Lippe Wassertechnik (Essen) deals with one of the largest usable groundwater resources in North Rhine-Westphalia, the Halterner Sanden (Dorsten-Haltern). The competing uses sometimes put such a heavy strain on the groundwater that surface waters such as the Hammbach dry up temporarily. To counteract this, together with partners, the company Lippe Wassertechnik developed a concept of measures which includes the closing of drainage ditches and a “traffic light” map as a decision support for water extraction. “The close coordination between farmers, nature conservationists and water suppliers was particularly helpful here,” Hempel describes the approach. A more efficient irrigation of agricultural land, the adaptation of cultivated crops and the renaturation of wetlands to keep water in the landscape were agreed.
In this context, DVGW Board Member Dr. Wolf Merkel advocates questioning the overall use of water. According to the Water Department of the German Technical and Scientific Association for Gas and Water (DVGW), it is necessary to discuss whether green areas and gardens should actually be irrigated with drinking water. Rather, the increasing demand for water, for example in agriculture, could in future also be met by reusing water. According to Merkel, treated municipal wastewater would then have to be treated for further use such as irrigation.
Another exemplary project of the Aueninstitut in Rastatt is concerned with giving flowing waters back free space for their natural, self-dynamic channel development. According to Project Manager Isabell Juszczyk, straightening and diking lead to a loss of biodiversity and water quality and increase the risk of flooding. The Aueninstitut, which is part of the Karlsruhe Institute of Technology, uses digital planning instruments to develop concepts for the Blies in Saarland, the Ammer in Bavaria, and the Mulde in Saxony. This can strengthen the ecosystem performance of river landscapes and reduce the costs of water management.
Floods and heavy rainfall events are another factor that climate change demands of urban water management. PIK scientist Hattermann: “If we look at Europe, we clearly see that precipitation tends to increase in Northern and Western Europe and decrease in Southern and Eastern Europe. And we in Germany are right in between and therefore have to adapt to both scenarios.”