Although Japan has not suffered any major disaster caused by storm surges or high waves since the Isewan Typhoon (Typhoon Vera) that ravaged the country in September 1959, tropical cyclones in other parts of the world have caused severe damage in recent years, including Hurricane Katrina that struck the U.S. in September 2005 and Typhoon Haiyan that devastated the Philippines in November 2013. In future, global warming might bring higher storm surges and waves than those we have experienced in Japan. Therefore, this research is aimed for changing disaster prevention and mitigation measures into a pre-disaster stage from post-disaster one and focuses on how to mitigate damage by the maximum storm surge and wave conditions and how to rapidly recover and reconstruct after the damage has occurred. Therefore, we conduct research to encourage hard and soft measures.

For our research to elucidate the oceanographic phenomena based on ocean observation data, we are continuously processing and analyzing wave observation data (preliminary and final processing, and statistical analysis)

For our research project simulating inundation events caused by waves inside ports, we are conducting an experiment using a planar model to study the inundation process on quay walls.

For our study of wave estimation techniques, we are improving the wave model based on its known shortcomings.

For our research on wave overtopping and force on seawall, we are conducting a model experiment examining the new types of seawalls that have been suggested in recent years.

For our research on the stability of filter materials under the impact of waves, we are conducting a model experiment to examine their stability when the seawall is under construction, etc.

For our research on the stability of filter materials under the impact of waves, we are conducting a model experiment to examine their stability when the seawall is under construction, etc.

We simulated the waves that occurred during Typhoon Faxai in 2019 using the spectral model WW3 and discovered that Yokohama Port,which suffered severe damage from the event, was hit by swells that had developed outside Tokyo Bay. Furthermore, we calculated the wave pressure that would impact vertical walls using the non-hydrostatic wave model SWASH and proved that the surf similarity parameter, Iribarren Number, could be used as an effective indicator of maximum swash height (wave pressure intensity).

We conducted a planar experiment simulating a container pier where inundation would occur due to wave overtopping on quay walls during storm surges and also ran calculations to reproduce the phenomenon.The experiment and calculation elucidated the space-time distribution of the inundation depth and flow speed behind the quay walls that no previous field survey of water marks could obtain, and also shed light on the inflow and outflow rates along the quay walls'normal line as well as on the planar process of inundation.

We estimated the storm surges that occurred in Tokyo Bay due to Typhoon Faxai in 2019 by applying the ROMS ocean model and analyzed the effects of the vertical distribution and temporal change of density fields on the tide anomaly. In addition, we developed a new method of correcting meteorological fields based on their relation to gradient winds.

We conducted cross-section experiments involving upright, overtopping-wave-permeable, double-parapet, and flare type seawalls to measure the wave overtopping rate, and calculated their equivalent crest height coefficients. In the case of the gently sloping seawall that we tested, it was found that the granular diameter of the mound rubble would cause the water level inside the mound to rise. We also used the CADMAS-SURF numerical wave flume and learned that granular diameter settings were important.

We built a nearly full-scale model of stone backfill and a rubble filter and applied waves to them to observe the stability of the rubble filter.It was found that the filter could dissipate waves as high as several tens of centimeters and so its stability could be evaluated by applying Hudson's formula.