Bild: Johannes Mitterer
Flash flood events have to be modeled using a combination of hydrological and hydrodynamic models. This hydrological-hydrodynamic coupling mechanism for the detailed investigaion of flash floods is not well investigated. The model coupling is intended to better represent flash flood events.
Two different coupling mechanisms are investigated. The internal coupling uses a simple hydrological approach (SCS-CN-method) directly integrated in the hydrodynamic model. The external coupling joins the hydrological and the hydrodynamic model via an interface. The hydrological model transfers the inflows from the catchment area as well as the effective precipitation to the hydrodynamic model. The hydrodynamic model resolves the detailed flow situation inside the endangered urban area. To limit the solution space, two scenarios A and B are considered. Scenario A is based on a continuous stream network, in scenario B on a plugged state is assumed. The preparation of the calculation requires extensive GIS work. The automation of this task is planned. Subject of scientific investigations are the comparison of different hydrodynamic models, the optimization of the flow formulas for the application in case of flash floods, as well as the mentioned coupling mechanisms.
Various questions have to be answered concerning the basic suitability of models, the spatial scaling effects of the modeling, the development of suitable interfaces between hydrology and hydrodynamics and the possibilities and limitations of the coupled scenario simulation. Due to complexity, the computing effort is expected to be high which will be reduced by the use of High Performance Computing (HPC).
Bild: Distribution of Reynolds-numbers