Towards a Better Understanding of Hurricane Disaster Risk: Assessing the Inland Hazards Associated with Hurricanes in the U.S. Atlantic Basin

The skill of tropical-cyclone (TC) track forecasts has steadily improved over the past decades, as has the understanding of TC risk in coastal regions. However, there is still much to be learned about the TC risk in inland regions, which is complicated by the presence of coastal evacuees, and includes hazards such as inland flash flooding and tornadoes. This was exemplified by Hurricane Ivan (2004), which spawned 118 tornadoes and produced significant rainfall amounts contributing to flooding inland. Ivan was responsible for 25 deaths in the U.S. and $18.8 billion (2004 USD) in damages. As part of a larger effort to improve the decision support tools available to emergency managers, this project seeks to map the inland U.S. hazards associated with TCs in the Atlantic Basin.

The specific hazards of TC-associated flash flooding (TCFF) and tornadoes (TCT) are assessed over approximately the last two decades using GIS. The highest TCFF hazard is indicated in southern Mississippi, Alabama, North Carolina and the Mid Atlantic Region, and TCT hazard is highest in the same region as TCFF, including Florida; stream-gage data additionally show that the highest TC-flood potential is in southern Florida. The TCFF and TCT data are smoothed at a county/parish level and then combined with a quantification of the social vulnerability of the exposed populations to derive a hurricane disaster risk index. The disaster risk index is also used in experiments with agent based modeling to assess evacuation behavior.