Integration of Coastal Inundation Modeling from Storm Tides to Individual waves Kwok Fai Cheung, PhD, PE Department of Ocean and Resources Engineering University of Hawaii at Manoa The Second International Workshop on the Application of Fluid Mechanics to Disaster Reduction IRIDeS, Tohoku University Sendai, Japan March 16, 2015 Coastal Flood Hazards due to Tropical Cyclones Hurricane Iniki 1992 Long time-scale processes • Barometric, wind, and wave setup • Astronomical tide Short time-scale processes • Wave runup Coastal Inundation • Combined effects of barometric, wind, wave setup, astronomical tide, and runup Image courtesy of NWS Model Package Case Study: Hurricane Iniki in1992 NEOWAVE + WAVEWATCH III + SWAN • NEOWAVE: nonhydrostatic long-wave model for astronomical tides and barometric and wind setup • WAVEWATCH III: Global and regional waves with CFS Reanalysis winds and parametric hurricane models • SWAN: adapted for wave setup • 2-way coupling and grid nesting 5 km resolution BOSZ • Optional module used instead of SWAN • Boussinesq model for wave-by-wave runup simulation 500 m resolution 50 m resolution 4~10 m resolution Hurricane Iniki 1992 51001 51003 51002 51004 Hurricane Iniki 1992 51001 51003 51004 51002 Hurricane Iniki 1992 Coupling of Tide, Surge, and Wave Setup Tide-surge Coupling in Hawaii Region Tide, Surge &Wave Setup Coupling at Nearshore Comparison with records at Port Allen tide gauge Linkage to Phase-resolving Wave Processes Important for Steep Volcanic Slopes of Hawaii • The Port Allen tide gauge recorded 1.4 m (above MSL) of maximum surface elevation during Hurricane Iniki • Floodwater reached 4 to 6 m elevation with maximum of 8 m indicative of wave runup NEOWAVE + SWAN • Storm surge (barometric and wind setup) and offshore wave spectra for BOSZ simulation of phase-resolving wave process Transfer of Storm Surge to BOSZ • Quasi-steady, spatially-variable storm surge elevation for modeling of individual wave propagation • Residual terms, gD/x and gD/y, from the long-wave equations with the assumption, U, V, and /t = 0 • Additional source terms, gD/x and gD/y, in the Boussinesq equations to maintain the storm surge in the domain Black line: MSL coastline; White dots: debris line Summary Incorporation of basin-scale processes in regional modeling of storm surge and wave setup Modeling of individual wave processes on quasi-steady, spatiallyvarying storm surge elevation Li, N., Roeber, V., Yamazaki, Y., Heitmann, T.W., Bai, Y., and Cheung, K.F. (2014). Integration of coastal inundation from storm tides to individual waves. Ocean Modelling, 83, 26-42.
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