18-9 Amplified Coastal Vulnerability in Southwest Florida in a Post-Hurricane Ian World: The Sedimentologic and Geomorphic Consequences of the 2023 and 2024 Tropical Storm Seasons

Session: Shaping a Sustainable Future with Geology in the Twenty-First Century: Geology and Society Division Turns 22

Presenting Author:

Michael Savarese

Authors:

Savarese, Michael¹, Bhatt, Dhruvkumar², Richards, Jeannine H.³, Ciarletta, Daniel J.⁴, Daly, Christopher⁵, Palmero, Rose V.⁶

(1) Marine & Earth Sciences, The Water School, Florida Gulf Coast University, Fort Myers, Florida, USA, (2) Marine & Earth Sciences, The Water School, Florida Gulf Coast University, Fort Myers, Florida, USA, (3) Ecology & Environmental Studies, The Water School, Florida Gulf Coast University, Fort Myers, Florida, USA, (4) U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida, USA, (5) Marine & Earth Sciences, The Water School, Florida Gulf Coast University, Fort Myers, Florida, USA, (6) U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida, USA,

Abstract:

Hurricane Ian made landfall on 28 September 2022 as a Category 4 storm, bringing extreme storm surge and wave erosion to the barrier islands and mainland beaches of Southwest Florida (Collier and Lee Counties). The geomorphic impacts were extensive with ebb surge channelization incising beaches and dune fields, and overwash eroding, de-vegetating, and reducing foredune amplitudes. Efforts to refortify the coast in the months following Ian were limited to infilling of surge channels and berm construction, raising backshore elevation in the vicinity of the damaged foredunes. The ensuing 2023 and 2024 storm seasons were highly active and punctuated by Idalia (August 2023), Debby (August 2024), Helene (September 2024), and Milton (October 2024), which left Southwest Florida in a much more vulnerable state. Since Ian, our team has worked to characterize these changes, producing assessments that have been shared with local jurisdictions (cities of Naples, Fort Myers Beach, Sanibel; and Lovers Key State Park) to assist their resilience building efforts. Some noteworthy realizations include: (1) Many of the ebb surge channels that appeared during Ian were reactivated by surge associated with the 2024 storms. This suggests that vulnerability to outwash may be predictable spatially. (2) Time series analyses of digital elevation models (DEMs) mapped after subsequent events highlight the increased susceptibility of damaged foredunes to overwash. (3) This result is further corroborated by the relative thicknesses of washover deposits from the 2024 storms, as revealed by sediment cores. (4) DEMs of Naples’s installed berm, acquired after each post-Ian event, documented the sediment and elevation loss due to the lack of stabilizing vegetation. These results prompted the development and funding of a new dune revegetation protocol for Collier County, Naples, and Fort Myers Beach. (5) Natural rates of vegetation recovery on dunes are slow and require annual monitoring and replanting with native vegetation to ensure the reestablishment of functional dune ecologies. As the work progresses, dune vegetation recovery and sediment trapping rates will be included in coupled geomorphic evolution and economic decision-making models to evaluate effective long-term management strategies, including natural infrastructure solutions. The coproduction of data from event-driven monitoring and modeling efforts with management insights from local jurisdictions will support science that has tangible and immediate value to coastal communities.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10693

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