Simulation of the December 2014 Nemuro Storm Surge and Incident Waves

抄録

 The storm surge due to the December 2014 Nemuro cyclone was hindcast using the Delft-3D/SWAN combined hydrodynamic and wave model with Japan Meteorological Agency (JMA) Mesoscale Model (MSM) reanalysis data as the surface boundary condition. Wind and pressure fields near Nemuro from the JMA MSM reanalysis data set agree with data from AMEDAS weather stations in eastern Hokkaido. The storm surge model result matches published measurements of water level and inundation extent in the town. Via application of the BOSZ Boussinesq-type wave model, the excitation of infragravity motions nearshore by this storm were found to be insignificant, but wave runup does cause an increase in the extent of inundation compared to that due to the still water storm tide hindcast by the Delft-3D/SWAN model.
 To evaluate the possible effects of climate change, a hypothetical storm with 150% the intensity of the 2014 cyclone was also simulated. Though the concrete armor units protecting the town's infrastructure are strong enough to escape damage from the hypothetical storm's waves, they are not high enough to prevent waves from riding atop the storm surge into low-lying areas of the town proper and the harbor. These waves are large enough to wreck residential buildings and pose a threat to life as well as property. Coastal hazards at locations in the midlatitudes, such as Nemuro, need to be reassessed accounting for the predicted effects of climate change, and adaptation strategies formulated based on local conditions.