Collaborative Research: RAPID: Hurricane Ian's overwash deposit: impacts of high-intensity landfalling tropical cyclones in southwest Florida

Tropical cyclones are amongst the most dangerous and costly natural hazards to impact U.S. coastlines. These events will have worsening effects with changing storm characteristics and sea-level rise in a warming climate. Most recently, southwest Florida has been impacted by two Category 4 hurricanes, Irma in 2017 and Ian in 2022. Two major events in the same region within 5 years presents a unique opportunity to study geological data from these storms. This rapid response project will explore the impact of high-intensity hurricanes by collecting geological data related to Hurricane Ian’s storm surge and sedimentary deposit. Further, previous work on Hurricane Irma in 2017 and 2019 will allow for a comparison between these two recent events. This multiple storm focus will help to understand the impact of hurricanes across the southwest Florida coast. The data will also add further knowledge about the preservation of geological deposits from repeated storms. Such data are crucial to improve understanding of past and present storm activity. The project advances broader representation in STEM through support of an all-female team of early career scientists and as well as undergraduate and graduate students. To extend our understanding of past tropical cyclones, we rely on geologic records to reconstruct a history of cyclone intensity and frequency beyond the instrumental period. However, reconstructing geologic records of tropical cyclones relies on modern analog studies of overwash deposits and how they are preserved in coastal environments. The aim of this study is to investigate two sites in southwest Florida by 1) measuring land elevation and recording the thickness and landward extent of Hurricane Ian’s overwash deposit and 2) comparing Ian’s deposit with a previous hurricane (Hurricane Irma) which also made landfall and deposited sediments throughout southwest Florida in 2017. The project is enabled by previous field investigations in 2017 and 2019 which documented Hurricane Irma overwash sediments in southwest Florida. Samples will be collected for sedimentologic (grain-size and organic content), geochemical (stable carbon isotopes and C/N values), and microfossil (foraminifera) analyses to compare biogeochemical indicators from Ian, Irma, and pre-storm sediments. Results of this project will advance paleo-storm studies in the sub-tropical southern Florida region by identifying key biogeochemical indicators and providing critical insight into the preservation potential of hurricane deposits in areas impacted by repeated, high-intensity hurricanes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.