Within the ElbeXtreme consortium in the framework oft he 3. DAM call for „Marine Extreme Events and Natural Hazards“ IOW is going to develop a high-resolution hydrodynamic model for the Elbe estuary. To do so, an existing coarse-resolution calibrated hydrodynamic Elbe model that follows the navigational channel using curvi-linear coordinates will be doubled in resolution. As hydrodynamic coastal ocean model GETM (General Estuarine Transport Model) will be applied. Once the model is readily calibrated the results will be made available to all project partners as one central product of this subproject.  Partners will be enabled to carry out own offline tracer transport calculations on the basis of these results. As further important step towards a simulation model for estuarine ecosystems, a suspended matter will be coupled that is able to realistically reproduce the dynamics of estuarine turbidity zones. As most important goal the simulations with this model should be able to reproduce extreme events, as hindcast simulations of real extreme events as well as synthetic simulations of constructed multiple extreme events (such as the occurrence of a storm surge during a river surge). The model developed by IOW will be coupled to pelagic and benthic ecosystem simulation modules, using the coupling sofware MOSSCO (Modular System for Shelves and Coasts) in collaboration with Hereon. By doing so, also ecosystem extreme events such as Harmful Algae Blooms should be simulated. Furthermore, IOW will also contribute with other partners to the definition of extreme events.