Abstract
An integrated storm surge modeling and traffic analysis were conducted in this study to assess the effectiveness of hurricane evacuations through a case study of Hurricane Irma. The Category 5 hurricane in 2017 caused a record evacuation with an estimated 6.8 million people relocating statewide in Florida. The Advanced Circulation (ADCIRC) model was applied to simulate storm tides during the hurricane event. Model validations indicated that simulated pressures, winds, and storm surge compared well with observations. Model simulated storm tides and winds were used to estimate the area affected by Hurricane Irma. Results showed that the storm surge and strong wind mainly affected coastal counties in south-west Florida. Only moderate storm tides (maximum about 2.5 m) and maximum wind speed about 115 mph were shown in both model simulations and Federal Emergency Management Agency (FEMA) post-hurricane assessment near the area of hurricane landfall. Storm surges did not rise to the 100-year flood elevation level. The maximum wind was much below the design wind speed of 150–170 mph (Category 5) as defined in Florida Building Code (FBC) for south Florida coastal areas. Compared with the total population of about 2.25 million in the six coastal counties affected by storm surge and Category 1–3 wind, the statewide evacuation of approximately 6.8 million people was found to be an over-evacuation due mainly to the uncertainty of hurricane path, which shifted from south-east to south-west Florida. The uncertainty of hurricane tracks made it difficult to predict the appropriate storm surge inundation zone for evacuation. Traffic data were used to analyze the evacuation traffic patterns. In south-east Florida, evacuation traffic started 4 days before the hurricane’s arrival. However, the hurricane path shifted and eventually landed in south-west Florida, which caused a high level of evacuation traffic in south-west Florida. Over-evacuation caused Evacuation Traffic Index (ETI) to increase to 200% above normal conditions in some sections of highways, which reduced the effectiveness of evacuation. Results from this study show that evacuation efficiency can be improved in the future by more accurate hurricane forecasting, better public awareness of real-time storm surge and wind as well as integrated storm surge and evacuation modeling for quick response to the uncertainty of hurricane forecasting.
Highlights
Storm surge is one of the major hazards affecting hurricane evacuation planning and operations in United States
Based on a case study of Hurricane Irma in 2017 landed in Florida, this paper presents an integrated study of storm surge modeling with evacuation traffic data analysis to enhance the understanding of how storm surge predictions affect evacuation traffic to support hurricane preparedness and responses
Storm surge modeling and traffic analysis were conducted to evaluate the effectiveness of the evacuations during Hurricane Irma
Summary
Hurricane evacuations [1,2] are often based on the forecasting of coastal hazard areas to be affected by storm surges and wind. A week before Hurricane Irma struck the Florida coast, the Florida Governor declared a state of emergency, based on potential storm surge area of the forecast hurricane track. With both the Atlantic and Gulf coasts of the state threatened, record evacuations ensued with an estimated 6.8 million people relocating statewide [19]. Three days before the hurricane landfall, it was forecast to move (as shown later in Fig. 13) along the Florida east coast, which caused a high level of evacuation traffic in the east coast. Results from this study will be helpful for emergency management agencies and coastal residents in providing improved understanding of the storm surge dynamics for better preparedness against hurricanes in the future
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