Study on future storm surge around Suo-nada Sea

Abstract: Japan lies on an area frequently hit by typhoons while city functions are clustered along the flat coastal areas, hence Japan has experienced lots of storm surge disasters up to the present. Coastal areas along the Suo-nada Sea also have the vulnerability against storm surge and in the past Typhoon 18 in 1999, Typhoon 16 and 18 in 2004 made remarkable damages in the areas. Furthermore, due to global warming, there are growing concerns about possible tremendous storm surge disasters caused by more furious typhoons than ever. Thus it is necessary to estimate the future storm surge for the coastal disaster prevention. The Suo-nada Sea, however, has some topographical factors which make storm surge estimations difficult. In this study, numerical simulations for storm surge around the Suo-nada Sea were performed by using a coastal circulation model FVCOM (Finite Volume Coastal Ocean Model) developed by Chen et al. (2003). FVCOM employs an unstructured grid system so as to accurately compute tidal currents even in complicated inner bays. First, appropriate computational domain was investigated. Then influences of various input data; calculation results by an empirical typhoon model, simulation results by a regional meteorological model and Grid Point Value, on the accuracy of simulations were examined. Next, future changes of typhoon characteristics around the sea area was investigated on the basis of Database for Policy Decision making for Future climate change (d4PDF). Finally, the future storm surge in Suo-nada Sea was estimated. From the simulations, it was found that more intense typhoons would strike the Suo-nada Sea and the direction of typhoon tracks would change toward the north in the future due to the global warming. It was also shown that the storm surge around the sea area can be more developed and cause more severe damages around the region in the future.