Climate change presents water authorities with the challenge of making decisions today on water withdrawals and competing uses, despite significant uncertainties regarding the future development of groundwater resources. Based on over 40 interviews, we present practical strategies, from more restrictive water rights to new cooperation models, that authorities have developed to address these challenges. From the identified strategies, we derive a guidance document that provides water authorities with practical orientation for dealing with climate-induced uncertainties and competing uses.

Groundwater availability in Germany is increasingly changing due to climate change and rising usage demands. Against the backdrop of potential water shortage situations, quantitative groundwater management is gaining greater focus in water management decision-making processes. Many water authorities face the challenge of having to decide on water withdrawals and usage conflicts today, despite considerable uncertainties regarding the future development of groundwater resources. Based on over 40 interviews conducted in the StressRes project, we analyse challenges and strategies of lower-level water authorities in Germany to manage groundwater sustainably even under uncertainty The focus lies on the development of new control mechanisms for usage conflicts as well as the role of data and digitalisation for sustainable groundwater management. We identify central challenges ranging from unclear water availabilities and legal frameworks to limited institutional capacities. Furthermore, we present practical solution approaches and strategies that authorities have already developed to address these challenges. These include more restrictive permitting procedures with flexible supplementary conditions, the expansion of digital monitoring systems, early cooperation forms with applicants, as well as enhanced inter-agency networking. At the same time, it becomes clear that decisions regarding water rights remain individual case decisions and reflect not only technical foundations but also societal priorities. Many solution approaches therefore require exchange between authorities as well as additional orientation and directives at higher levels, such as through state authorities. From the identified strategies, we derive a guidance document that provides water authorities with practical orientation for dealing with climate-induced uncertainties and competing uses.