Water suppliers face major challenges such as climate change and population growth. To prepare for the future, detailed knowledge of water resources is needed. In southern Germany, the state water supplier Zweckverband Landeswasserversorgung provides 3 million people with drinking water obtained from a complex karst and alluvial aquifer system and the river Danube. In this study, a combination of different tracing techniques was used with the goal of a multi-scale characterization of the aquifer system and to gain additional knowledge about groundwater flow toward the extraction wells in the Danube Valley. For the small-scale characterization, selected groundwater monitoring wells were examined using single-borehole dilution tests. With these tests, a wide range of flow behavior could be documented, including fast outflow within just a few hours in wells with good connection to the aquifer, but also durations of many weeks in low-permeability formations. Vertical flow, caused by multiple flow horizons or uprising groundwater, was detected in 40% of the tested wells. A regional multi-tracer test with three injections was used to investigate the aquifer on a large scale. For the highly karstified connection between a swallow hole and a spring group, high flow velocities of around 80 m/h could be documented. Exceptionally delayed arrivals, 250 and 307 days after the injection, respectively showing maximum velocities of 0.44 and 0.39 m/h, were observed in an area where low-permeability sediments overlay the karst conduits. With the chosen methods, a distinct heterogeneity caused by the geological setting could be documented on both scales.

供水商面临气候变化和人口增长等重大挑战。为了为未来做准备，需要详细了解水资源。在德国南部，州供水商 Zweckverband Landeswasserversorgung 为 300 万人提供从复杂的喀斯特和冲积含水层系统以及多瑙河获取的饮用水。在这项研究中，结合使用不同的示踪技术，目的是对含水层系统进行多尺度表征，并获得有关流向多瑙河谷抽取井的地下水流的更多知识。对于小规模表征，使用单钻孔稀释试验检查选定的地下水监测井。通过这些测试，可以记录各种流动行为，包括在与含水层有良好连接的井中仅几个小时内的快速流出，以及在低渗透地层中持续数周的持续时间。在 40% 的测试井中检测到由多个流动层位或上升的地下水引起的垂直流动。使用三次注入的区域多示踪剂测试对含水层进行了大规模调查。对于燕子孔和弹簧组之间的高度岩溶连接，可以记录大约 80 m/h 的高流速。在低渗透沉积物覆盖岩溶导管的区域，观察到在注入后 250 天和 307 天到达异常延迟，最大速度分别为 0.44 和 0.39 m/h。通过选择的方法，可以在两个尺度上记录由地质环境引起的明显异质性。