In the Hydrogeology Research Group, we aim to improve the conceptual and quantitative understanding of surface water-groundwater interactions in diverse environments. We base the characterization of hydrogeological and ecohydrological processes on two fundamental pillars: (a) on diverse observations of hydrological and biogeochemical fluxes and processes, and (b) on integrated surface-subsurface hydrological models (ISSHM). On the one hand, integrating observations that represent different spatial and temporal scales is necessary to characterize the highly dynamic and complex behavior of hydrological and biogeochemical processes in the subsurface, on the surface, in the atmosphere and in the biosphere. On the other hand, numerical models able to simulate all relevant fluxes and processes throughout both the surface and the subsurface in a physically based manner are necessary to quantify and predict the current and future behavior of hydrogeological systems. To take full advantage of both domains in the advancement of our understanding of hydrological and biogeochemical processes in surface water-groundwater systems, we integrate both components via state-of-the-art model calibration and data assimilation algorithms.

We currently focus our efforts on developing and employing novel hydrological tracer techniques and on advancing the simulation of surface water-groundwater systems with ISSHM by calibration against tracer data. Tracer techniques that we currently develop and employ include dissolved atmospheric noble gases, microbial information based on environmental DNA or flow cytometry, and naturally present radioactive tracers such as ²²²Rn, ³⁷Ar or ³H/³He. We are particularly interested in using techniques that allow near real-time measurements of tracers online and directly in the field.

Special attention, however, is dedicated to investigations of the complex and dynamic surface water-groundwater interactions that occur along the gravelly alluvial rivers that are used for drinking water production via bank filtration, which in Switzerland account for around 30% of the total drinking water production, and in Europe for more than 50%.