Operational wave forecast in the German Bight as part of a sensorand risk based early warning system

Today's available flood- respectively storm surge warning systems for the German North Sea coast consist exclusively of water level forecasts. Other hydrodynamic loads caused by wind waves and local currents as well as the resistance of the flood protection structure itself (e.g. coastal dikes, flood protection walls etc.) are not taken into account. Therefore, an operational now- and forecast system for waves and wave induced hydrodynamic loads is set up that consists of available field measurements and data from numerical wave simulations in the German Bight. A hybrid model approach is used for the forecast of hydrodynamic loads on sea dikes. The approach combines numerical results from the phase integrated spectral wave forecast model (SWAN) and an empirical wave run-up approach (EurOtop) for the now- and forecast of average wave run-up heights at a sea dike on the North Frisian Island of Pellworm. The operational system is demonstrated exemplarily for the forecast of a severe storm event on the 5-6th December 2013 (German name "XAVER"). The qualitiy of the forecast is assessed seperately for the local nearshore wave conditions as well as the average wave run-up heights on the basis of available field measurements.