REVEALING THE GEOMORPHOLOGIC IMPACTS OF HURRICANE IAN IN SOUTHWEST FLORIDA USING GEOSPATIAL TECHNOLOGY

Abstract. Geospatial data were used to analyze changes to geomorphology of barrier islands and beaches in Southwest Florida resulting from Hurricane Ian in late September 2022. The hurricane generated high intensity winds and storm surge causing more than $112 billion in damages, along with massive sediment mobilization due to erosion and deposition. This study quantified net sediment loss and gain on specific barrier islands by storm surge (Sanibel, Naples, Fort Myers Beach, others, though this paper focuses exclusively on Sanibel) by comparing pre- and post-Ian topography generated by a drone-flown LiDAR sensor; changes in elevation were used to quantify spatial variation in sediment volume. Data were collected immediately after Hurricane Ian and compared against topographic data collected by NOAA in 2018. Digital elevation models (DEMs) were used to compare topography, shoreline positions (relative to Mean High Water), foredune position, and volumetric changes using GIS technology. In general, the shoreline position after Ian changed little, indicating that the incoming surge had little influence on the beach. The foredunes, however, were deflated and set back by surge overwash. The outgoing surge created a much more dramatic geomorphologic change. Erosional surge channels cut through the foredunes and upper beach berm along many regions of the coastline. The ebb erosion also caused extensive damage to physical structures when located immediately behind the foredune. Lastly, this work demonstrates the value of employing GIS and remote sensing technology to problems of beach and dune management, the restoration of coastal ecosystems, the enhancement of resilience capacity of both natural and developed infrastructure, and the development of new policy needed to contend with the effects of climate change.