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Wang, P.; Adam, J.D.; Cheng, J., and Vallée, M., 2020. Morphological and sedimentological impacts of Hurricane Michael along the northwest Florida coast. Journal of Coastal Research, 36(5), 932–950. Coconut Creek (Florida), ISSN 0749-0208. On October 10, 2018, category 5 Hurricane Michael made landfall at Mexico Beach, generating a nearly 5-m storm surge. The greater landfall area is characteristic of a cuspate headland protruding into the Gulf of Mexico for up to 50 km. The headland is composed of several barrier islands with different orientations fronting a large estuary. The hurricane-impacted areas include densely developed small beachfront communities, modestly to sparsely developed shoreline communities, mostly pristine state parks, and a completely pristine national wildlife refuge. Therefore, Hurricane Michael provides an excellent opportunity to study the impact of an extreme storm over various coastal environments with different degrees of human developments. Because of the shoreline orientation and bathymetry changes induced by the headland, the wave field associated with the hurricane is complicated, with different locations for the highest wave and the landfall site where the surge and wind speed were the greatest. Numerical wave modeling revealed two wave-focusing points along the headland where barrier-island breaching occurred. Beach-dune erosion and impact to infrastructure were examined and compared among various natural–human coastal systems. The magnitude of dune erosion was mostly controlled by the storm wave height and prestorm beach width, but the height of the prestorm dune was not a determining factor. Sedimentological characteristics of storm deposits along the barrier islands, within Apalachicola Bay, and in the surrounding coastal marsh were examined using 116 sediment cores and 40 grab sediment samples. Characteristics of storm deposits and their preservation are described for various subenvironments, including beaches, dunes, interior wetlands, back-barrier bay, and coastal marsh along the landward side of the estuary. The landward penetrations of identifiable sandy overwash deposits were less than 150 m along the barrier islands and less than 30 m along the mainland marshes. These results should have potential implications on paleostorm study. [ABSTRACT FROM AUTHOR]

Cheng, J. and Wang, P., 2019. Unusual beach changes induced by Hurricane Irma with a negative storm surge and poststorm recovery. Journal of Coastal Research, 35(6), 1185–1199. Coconut Creek (Florida), ISSN 0749-0208. The coast of west-central Florida, facing the Gulf of Mexico, experienced Hurricane Irma with a negative surge of 1.1 m and a highly oblique northerly approaching wave in September 2017. This unusual hydrodynamic condition provides an opportunity to investigate the effect of surge and incident wave direction on morphology changes. Beach profiles, spaced at 300 m apart, along a 15-km stretch of beach were surveyed 2 weeks prior to the passage of Hurricane Irma and 1 week after and continued for up to 5 months after the passage to obtain Irma-induced erosion as well as post-Irma recovery. Owing to the occurrence of negative surge, the profile volume of the dune field remained mostly stable. The majority of beach erosion occurred below mean sea level, with a considerable amount of sediment transported seaward of the depth of closure. This is opposite to the conservation of beach profile volume above depth of closure under several earlier storms with a positive surge. The alongshore variation of overall beach profile volume erosion demonstrates a southward decreasing trend, due to a southward decreasing wave height as controlled by the northerly incident wave. After the passage of Irma, minor beach volume recovery occurred during the calm period of the fall season. Opposite to the typical erosive beach in winter, the most substantial beach accretion and onshore bar movement were observed during the following peak winter season as beach/bar evolved toward equilibrium. The profile volume in the dry beach region experienced a complete recovery in the first 5 months after Hurricane Irma. Shoreline change is a valid proxy for beach volume change during both the erosive and the recovery phase of Irma. The systematically measured beach profiles provide a solid dataset to calibrate process-based models to study beach morphodynamics. [ABSTRACT FROM AUTHOR]