A HURRICANE WAVE AND SURGE FORECASTING SYSTEM IN HAWAII

This study presents an efficient operational model that can be used by civil defense agencies for real-time prediction and fast warnings on hurricane-generated wind wave and storm surge. The wind waves are simulated by the hyperbolic wave model of the mild-slope equation type, instead of using wave models such as WAM, SWAN which are most widely used in the world. In the present model, a new concept of wavelength modulation is employed to enhance the model application to broader ocean area. The simulated results showed reasonable agreement with the recorded wind waves around Hawaii islands and with measured storm surges near the south shore of Kauai Island where Iniki made landfall on September 11, 1992. The wave setup was estimated to produce apparent sea levels only when wind waves propagated toward the south shore. The total sea-level residual, obtained by adding the calculated wave setup to the storm surge is qualitatively similar to the measured sea-level residual. The present numerical results revealed that the dominant forcing factors for the storm surge generation by Hurricane Iniki in Hawaii are the drop in atmospheric pressure near the eye of the hurricane and breaking wave-induced setup, while the wind-generated surface stress has little direct effect in generating the surge.