The general research area is modeling of hydro- and environmental systems, a fundamentally-orientated reserach field. This modeling encompasses natural and technical systems, the integration of buildings and the flows of water and air through or around such systems as well as the transport of substances and energy. It demands for a good physical process understanding, a wide range of simulation methods in combination with powerful information-processing methods and techniques as well as the interaction to experimental works. Modeling of hydro- and environmental systems increasingly devolves to integrated approaches as it accounts for the interactions of compartments. In the following, three research topics which are dealt with at the chair are listed.