Validation of a Bathymetric Storm Surge Scale

Lau, Y. H., Fitzpatrick, P. J., Li, Y., & Hill, C. M. (2012). Validation of a Bathymetric Storm Surge Scale. 92nd American Meteorological Society Annual Meeting. New Orleans, LA.

his paper investigates the contributions of maximum sustained 10-m winds (Vmax), storm size, and translation speed to storm surge for five idealized bathymetry profiles that vary by nearshore water depth and continental shelf length, based on simulations using the ADvanced CIRCulation model. Depending on intensity, peak surge differs by 4.5-7 m between shallow and deep bathymetries. Adjustments of 7-16% for hurricane size are required in most bathymetries, but modifications for translation speed (8-19%) are only needed in shallow bathymetries. The wave setup contribution to peak surge, using dynamically-based empirical formulations, suggest these results will increase by 0.2-0.4 m in shallow bathymetries, 0.4-0.6 m in moderate bathymetries, and 0.6-0.8 m for deep bathymetries for minor hurricanes, and by 0.3-0.5 m, 0.5-0.8 m, and 0.8-1.5 m for the same respective bathymetries in major hurricanes. These relationships could also be used for guidance if numerical model guidance is unavailable. To facilitate this process, we define five bathymetry zones of increasing surge susceptibility which provide a range of peak surge values. In principle, one identifies the zone which best represents a location\'s ocean floor profile, picks the peak surge range for a given intensity, and adjusts the corresponding surge range for size, speed, wave setup, and tide. These relationships are validated against historical hurricanes\' storm surge from 1960-2008. The possibility of using these results and concepts towards the development of storm surge guidance and related products (such as indexes) is also discussed. The distance of 1.5-m and 3-m surge inundation from landfall for the onshore wind section is also computed for the bathymetry variations. Shallow bathymetries experience significant inundation far from landfall. Surprisingly, inundation levels outside landfall regions differ little between Category 3 and 5 hurricanes and may be predictable in major hurricane events. Integrated Kinetic Energy (IKE) as a surge variable is also investigated. IKE alone does not correlate well to peak surge, but shows potential as IKE^m X Vmax^n (m between 0.3 and 0.8; n between 1 and 2) when partitioned by the five bathymetry profiles. An analytical solution for IKE based on the Holland wind formulation is presented.