In the context of this research topic methods and techniques to model flow and transport processes in surface waters are developed and applied. 1D-, 2D- and 3D-flows as well as the transport of substances (tracer, salt, ...), heat, sediments and reaction processes are simulated. The software technical basis for implementing 2D-model concepts and numerical methods is the modeling framework Hydroinformatics Modeling System (HMS) being developed at our chair. Furthermore, mainly freeware models (TELEMAC-MASCARET, OpenFOAM) are used. Application fields are, for example, flood simulations, river restoration, flow and transport simulations in urban and rural areas as well as runoff simulations in small catchments.