RETURN TO THE HURRICANE IMPACT SCALE: TESTING ITS LARGE-SCALE APPLICATION

Among the many hazards associated with hurricanes, storm surge is responsible for the most economic damage and mortality. Described by NOAA as an “abnormal rise in water generated by a storm,” storm surge can cause extreme flooding when it progresses too far inland. Therefore, an understanding of storm surge is essential to develop proper preparation and response plans for future threats. The Saffir-Simpson Scale (SSS) is used to classify hurricanes. The SSS, however, is based only on sustained wind speed, which is obviously of critical importance, but it is well understood not to be the only major control on storm surge and thus, not always the best indicator of a hurricane’s damage potential. The size of the storm, its track, its pressure, its forward speed, and, most often neglected by the media, the geologic setting of the landfall area also play important roles in affecting the overall magnitude of the surge. These factors, when combined with the density and type of coastal development, contribute to the overall damage potential.

Underestimating storm surge is a costly affair. Unprepared communities can find themselves nearly destroyed, with the rest of society left to fund the repair. Young et al. (1999) introduced the Hurricane Impact Scale (HIS) which emphasizes storm surge as a means of summarizing the overall magnitude of energy conveyed by a hurricane, with the hope of, ultimately, promoting safer coastal planning and building practices. The Hurricane Impact Scale (HIS) has undergone some revision since its creation, but has not yet left the trial phase. This study represents the beginning of a large-scale application of the HIS using data obtained from the Program for the Study of Developed Shorelines (PSDS) storm-surge database. Profiles were created by plotting the scaled along-coast spacing of storm-surge data points against their elevation. Combining these two factors determines storm-surge spread and maximum, allowing for numerical classification using the HIS. This process can be replicated with the remaining data on the PSDS website (http://stormsurge.wcu.edu/). Seven hurricanes which hit Eastern states have been evaluated. Preliminary results suggest that the HIS value of a hurricane is approximately ±1 from its Saffir-Simpson scale value.