The critical zone describes the dynamic range of the interaction of atmosphere, hydrosphere, biosphere and upper lithosphere and extends from the treetops to the base of the aquifers. The current changes in climate and environmental conditions remind us of the complexities that require a broad and comprehensive approach to natural systems. With “critical zone”, a broad target area is deliberately chosen, knowing that the LIAG only deals with individual aspects. Thus, the non-invasive geophysical methods of the institute provide important contributions to the spatial structure, to hydraulic parameters and, through models and simulations based on them, also to understanding the processes taking place here. An important piece of the puzzle is the vadose zone between the aquifer and the earth's surface which is highly variable in time and space. The transport processes that take place here are of great importance for the input of nutrients and pollutants into the groundwater and the exchange with the atmosphere.