Global storm surge forecast and inundation modeling

Tropical cyclones (TCs) are some of the most damaging events. They occur in yearly cycles and affect the coastal population with three dangerous effects: heavy rain, strong wind and storm surge. In order to estimate the area and the population affected by a cyclone, all the three types of physical impacts must be taken into account. Storm surge is an abnormal rise of water above the astronomical tides, generated by strong winds and drop in the atmospheric pressure. The report describes the implementation of such phenomena in the JRC HyFlux2 code, which is routinely used in GDACS (www.gdacs.org) to model inundations due to tsunami run-ups. The first aim of this work is to identify which source of information (provided by the different weather forecast centers) allows the specification of the pressure and wind fields of the TCs at global level. The lack of a global and free downloadable TC wind and pressure datasets has led the JRC to develop a Monte Carlo method to determine the Holland's parameters using the world available wind radii data (advisory and forecast). The obtained Holland's parameters are therefore used to obtain pressure and wind fields which are the forcing of the HyFlux2 storm surge modeling. The developed methodology has been validated for four TCs: Earl, Nargis, Katrina and Yasi. The preliminary results show that it is possible to forecast the effects of storm surges by several days in advance.