Groundwater is the most important source of drinking water worldwide. Its quantity and quality is threatened, e.g. by unsustainable use, diffuse input of anthropogenic pollutants, and anthropogenic changes of biogeochemical conditions.
It is now well accepted that groundwater protection requires considering the coupled terrestrial hydrosystem at catchment scale, including atmospheric and land-surface processes, surface-water bodies, and processes in the unsaturated soil zone and in the aquifer. The related process descriptions are uncertain; they are affected by heterogeneity, and undergo change.
Sustainable management of groundwater resources under climate and land-use change requires predictive models simulating all relevant hydrological and (biogeo)chemical processes as coupled systems, explicitly accounting for feedback mechanisms. Such physics-based coupled modelling platforms have now reached a state in which they start to get applied in quantitative water resources man-agement. Extensions to water quality, however, are still in their infancy and face particular challenges on the conceptual level and in upscaling to the catchment scale.
The RTG is closely related to the Collaborative Research Center CAMPOS - Catchment as Reactors, facilitating interdisciplinary research in the fields of water and solute fluxes at the catchment scale as a function of climate and land use changes.