[en] Laboratory experiments with groundwater flow models and column devices are outlined and results are given of measurements determining the amount of deuterium, oxygen-18, carbon-14, and krypton-85 in precipitation samples and in running-off snow water, as well as of experiments on the impact of light on fluorescent dye solutions. The field experiments included flow measurements on groundwater and surface waters, tracer experiments, hydrogeologic, and hydrological studies with the aid of isotopes. (HK)