The International Research Training Group (IRTG) “Integrated Hydrosystem Modelling” at the Universities of Tübingen and Hohenheim (Germany), and Waterloo (Canada) targets at developing and applying numerical models of flow and reactive solute transport in coupled hydrosystems comprising of land-surface and subsurface compartments. These models are needed to assess the impacts of environmental change on water quantity and quality at catchment scale. The IRTG offers a structured PhD program at the German partner universities with joint international training and supervision.