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Wang, L.; Bianchette, T.A., and Liu, K.-b., 2019. Diatom evidence of a paleohurricane-induced coastal flooding event in Weeks Bay, Alabama, USA. Journal of Coastal Research, 35(3), 499–508. Coconut Creek (Florida), ISSN 0749-0208. Sand layers deposited in coastal backbarrier lakes and marshes have been taken as indicators of overwash processes generated by hurricane landfalls, but sand layers discovered in sediments from non-backbarrier estuarine settings have not been as thoroughly investigated. Sedimentological and diatom analyses of a 44-cm core (WB 08-04) taken from a seep forest on the north shore of Weeks Bay in southern Alabama contains an 8-cm-thick sand layer embedded in dark gray peat. As an aid to determining the provenance of the sand layer, diatoms were also analyzed from eight surface samples taken from five nearby environments representing different salinity conditions. The diatom assemblage in the sand layer is dominated by acidophilous (Eunotia spp., Frustulia krammeri) and freshwater (Pinnularia neomajor, Pinnularia latevittata) species, suggesting that they were transported by fluvial processes from the acidic and freshwater bogs above the banks of Fish River. The sand layer also contains small percentages of brackish and marine diatoms (Tryblionella marginulata, Planothidium delicatulum), suggesting that incursion of seawater and brackish water from Weeks Bay and Mobile Bay also played a role in its deposition. It is inferred that the sand layer was deposited by a hurricane that brought both intense precipitation to coastal Alabama and a storm surge into Weeks Bay. Heavy rainfall caused overbank flooding of Fish River, which transported sand from the river banks and diatoms from nearby bogs to the coring site. Concurrently, storm surge waters also deposited marine and brackish diatoms at the site. Historical records suggest that the Bernard Romans' Gulf Coast Hurricane in AD 1772 may have been responsible for the flooding that resulted in the deposition of the sand layer. [ABSTRACT FROM AUTHOR]

The Louisiana shoreline is rapidly retreating as a result of factors such as sea-level rise and land subsidence. The northern Gulf of Mexico coast is also a hotspot for hurricane landfalls, and several major storms have impacted this region in the past few decades. A section of the Louisiana (USA) coast that has one of the highest rates of shoreline retreat in North America is the Caminada-Moreau headland, located south of New Orleans. Bay Champagne is a coastal lake within the headland that provides a unique opportunity to investigate shoreline retreat and the coastal effects of hurricanes. In order to examine the influence of hurricanes on the rate of shoreline retreat, 35 years (1983–2018) of Landsat imagery was analyzed. During that period of time, the shoreline has retreated 292 m. The overall rate of shoreline retreat, prior to a beach re-nourishment project completed in 2014, was over 12 m per year. A period of high hurricane frequency (1998–2013) corresponds to an increased average shoreline retreat rate of >21 m per year. Coastal features created by multiple hurricanes that have impacted this site have persisted for several years. Bay Champagne has lost 48% of its surface area over the last 35 years as a result of long-term shoreline retreat. If shoreline retreat continues at the average rate, it is expected that Bay Champagne will disappear completely within the next 40 years. [ABSTRACT FROM AUTHOR]