HURRICANE EVACUATIONS AS A METRIC FOR SOCIETAL VULNERABILITY

Open Access
Author:
Clark, Allyson
Area of Honors:
Meteorology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Jenni Evans, Thesis Supervisor
  • Paul Markowski, Honors Advisor
Keywords:
  • evacuation
  • hurricanes
Abstract:
Analyses of the variations in societal vulnerability to hurricanes and the impacts of hurricane forecasts help to mitigate vulnerability are the subject of this research. An index of societal variability is developed based on the idealized costs of evacuation owing to hurricane landfall. Evacuation populations are chosen as a forecast metric because evacuation zones combine information about hurricane track and intensity, population density and the areas of greatest vulnerability due to coastal bathymetry and topography (which affect storm surge) and available evacuation routes. Thus, idealized evacuation statistics capture the societal impact of forecast and realized storm track and intensity. For the initial analysis, the study focuses on the forecasts of the seven hurricane landfalls in Florida during the 2004 and 2005 hurricane seasons using the National Hurricane Center (NHC) best track for validation. The official forecast was compared with operational model forecasts that were available at the time. Forecasts of minimum pressure, wind intensity, and landfall coordinates are compared with conditions at landfall. A vulnerability index value for the total cost of an evacuation is computed, taking into account both the cost of evacuating the population of a region, including “correct” evacuations and over-warning, and the costs incurred by not evacuating a population actually impacted at landfall. These measures are compared with the cost of a perfect forecast. Analyses of this index are completed for forecasts in six-hour intervals from the initial NHC tropical storm watch declaration up to landfall. A Tropical Cyclone Game (TCG), a descendant of the Hurricane Game developed at Colorado State in the 1980s, was developed to provide a more nuanced perspective on evacuations due to approaching hurricanes. This model includes parameterizations of population awareness and likelihood of evacuation in the presence of an approaching storm. Forecast information was also analyzed using the TCG to compare the vulnerability index costs to potential (and less extreme) evacuation scenarios.