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Vasseur, P.L.; Collins, S.A., and Selman, W., 2023. Effects of tropical cyclones and other severe weather events on Reddish Egret (Egretta rufescens) populations in Louisiana, U.S.A. Journal of Coastal Research, 39(6), 1124–1136. Charlotte (North Carolina), ISSN 0749-0208. Tropical cyclones (i.e. tropical depressions, tropical storms, and hurricanes) and other extreme weather events directly impacting Louisiana from 2016–21 were examined to determine their effects on adult Reddish Egrets equipped with satellite transmitters in SE (n = 11) and SW (n = 14) Louisiana. Fourteen tropical cyclones (six hurricanes, five tropical storms, one tropical depression, and two extratropical cyclones) impacted Louisiana during the study, and telemetry data were reviewed immediately on and around (±1 day) the arrival of each storm to monitor any movements and individual survival. As many as nine of 25 (36%) transmittered Reddish Egrets presumably died from the direct impacts of five tropical cyclones; seven of nine mortalities were associated with three major hurricanes. Mortality was presumed based on stationary GPS fixes for multiple days or the termination of data transmission following a storm. All mortalities were presumed, as no carcasses were recovered. Previous telemetry studies reported Reddish Egrets often survived intense tropical cyclones and direct impacts were not appreciable at the population level. Yet, more than one-third of the transmittered birds in the sample population potentially died from storm-related impacts, and the population may have declined drastically, assuming some unmarked individuals also likely died. Because the Reddish Egret is restricted to coastal habitats, the species appears to be particularly vulnerable to tropical cyclone effects. If predictions of increased frequency and intensity of tropical cyclones by the end of this century are accurate, these storms pose a significant threat to Reddish Egret populations. With accelerated loss and degradation to suitable coastal habitats, protection and restoration of key foraging and nesting sites for sensitive species similar to the Reddish Egret are needed in Louisiana and other disturbance-prone areas along the Gulf Coast. [ABSTRACT FROM AUTHOR]

Brown, M.T.; Dix, N.; Osborne, T.; Castle, A.; Woodward, W.; Hartnett, A.; Dunnigan, S.; Tanner, S., and McGinley, E., 2023. The impacts of a restoration dredging project and storm events on water quality in a northeast Florida barrier island estuary. Journal of Coastal Research, 39(4), 722–739. Charlotte (North Carolina), ISSN 0749-0208. Previous studies in estuarine systems have demonstrated that both dredging projects and storm events can have profound impacts on water quality, particularly increases in nutrients, sediment loading, and shifts in phytoplankton community biomass. This study provided the opportunity to assess the potential relative impacts of a 9-month-long barrier island restoration dredging operation, in comparison to storm events that shortly followed, on water quality in a well-flushed, subtropical NE Florida estuary. Twice-a-month monitoring of turbidity, total suspended solids, chlorophyll-a, and major nutrients (ammonium, nitrate+nitrite, and orthophosphate) was carried out at six sites near the dredging operation area from November 2016 through October 2018. This timeframe sampled the dredging project from January to September 2017 associated with the reopening of the Summer Haven River on the barrier island side of the Matanzas River estuary. In addition, two major storm events, Hurricane Irma in September 2017 and a 5-day nor'easter in October 2017, took place during the water quality monitoring. Although the dredging project did result in notable impacts on total suspended solids and ammonium concentrations, the results highlight how natural storm events can have more significant and lasting impacts on water quality in a well-flushed estuary, particularly with regard to decreases in salinity, input and remineralization of dissolved organic carbon, and increases in dissolved nutrients. [ABSTRACT FROM AUTHOR]

Jose, F. and Carlin, F., 2022. Storm-driven morphodynamics of a sandy beach in Florida. Journal of Coastal Research, 38(5), 896–907. Coconut Creek (Florida), ISSN 0749-0208. Barrier islands and sandy beaches are considered important economic and environmental assets. Florida's gulf coast has one of the most morphologically diverse barrier island systems in the world, with a delicate balance between tidal and wave-generated processes that rapidly bring about morphological changes on this low-energy coast. Significant morphological response can evolve in the coastal zone because of natural phenomena such as hurricanes and tropical storms, as well as anthropogenic activities and coastal engineering projects (Davis and Barnard, 2003). The study uses LIDAR data and historical Google Earth images to assess the long-term morphological and volumetric evolution of Casey Key in Sarasota County, Florida, in response to major storms and anthropogenic activities. Casey Key overall has proven resilient to erosion, especially an 8-km-long middle segment, despite being battered during the 2004 hurricane season, when it is estimated that 608,094 m3 of sand was lost. The key appears to be mostly stable, and it has since recovered the loss and even received benefits from failed nourishment projects to the north. However, the northernmost 2.5-km shoreline of the key is highly vulnerable, with as much as 50 m of retreat in some areas that threatens houses and beach development. Construction of jetty at the south end of the island resulted in enormous progradation of the beach at the expense of excessive downdrift erosion and retreat of the barrier island just south of Casey Key. [ABSTRACT FROM AUTHOR]

O'Grady, J.G., 2024. A parametric model of tropical cyclone wave fields. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 991-995. Charlotte (North Carolina), ISSN 0749-0208. Tropical cyclones (TCs), generate strong winds, creating large wind-sea and swell waves which cause hazardous ocean conditions which propagate towards the shore, resulting in hazardous surf conditions, coastal inundation, and erosion. The largest waves generated by a TC are collocated with the radius of maximum winds, on the side of the storm where the winds align with the forward TC motion (left side of the forward motion for the southern hemisphere, right for the northern hemisphere). Wave fields can be predicted effectively with numerical spectral wave models. However, such models can be expensive in terms of their computational and input data requirements. Due to the infrequency of TC occurrences in the observed record, a common approach to assessing the likelihood of TC hazards is the generation of large numbers of synthetic cyclones. To achieve this, simplified and computationally efficient nondynamic parametric cyclone wave field models enable rapid approximations of the wave field surrounding the cyclone from a limited number of input parameters. In this study, we develop an empirical equation to model wave height fields. This model builds on previous empirical and semi-empirical models based on wave buoy observations and aircraft transits of historic TCs in the North Atlantic and Gulf of Mexico. It requires inputs of local wind speed, TC size, and motion parameters. The development of this model incorporates a larger sample of TCs and wave buoy data from the same ocean basins. This wave field model is part of an open-source effort to simulate multi-hazards arising from TCs. [ABSTRACT FROM AUTHOR]

Harris, M.E. and Ellis, J.T., 2021. Comparing tropical cyclone and king tide impacts on a South Carolina coastal dune system. Journal of Coastal Research, 37(5), 923–932. Coconut Creek (Florida), ISSN 0749-0208. Coastal populations face an ever-growing threat as natural hazards increase in frequency and magnitude. In South Carolina, king tides (abnormally high tides) responsible for coastal flooding have increased by 126% between 2014 and 2019. King tides present an evolving threat as sea levels rise, yet the implications for coastal dune response have not been investigated. This study compares the geomorphic impacts from king tides to two tropical cyclones on a South Carolina barrier island during four time periods (TPs): Hurricanes Florence (TP1) and Michael (TP2) and two subsequent periods (TP3 and TP4) with king tides but devoid of tropical cyclone activity. Florence resulted in the greatest average change to the dunes, with normalized volumes (nv) equivalent to –11.6 m3/d. During Michael, the average change rate was nv = –1.5 m3/d. Dune changes during TP3 and TP4 averaged nv = –1.7 m3/d and nv = –2.3 m3/d, respectively. The reduction rate during nonstorm conditions is indicative of the erosive potential of king tides. The erosive potential should be further investigated in conjunction with king tide magnitude and frequency. Smaller, more pervasive coastal hazards, such as king tides, should be more strongly considered, in addition to larger singular events, such as tropical cyclones, when investigating the geomorphic change of coastal dune systems. [ABSTRACT FROM AUTHOR]

Lindner, B.L.; Holden, W.; Neuhauser, A., and Evsich, R., 2020. Climatology of tropical cyclone strikes along the southeastern coastline of the United States. Journal of Coastal Research, 36(6), 1162–1177. Coconut Creek (Florida), ISSN 0749-0208. It has been theorized that tropical cyclones originating in or passing through the Gulf of Mexico (hereafter referred to as GOM tropical cyclones) may significantly impact communities along the Atlantic coast of the southeastern United States. To explore this hypothesis, site-specific climatologies were compiled using National Hurricane Center records of tropical cyclones that passed within 139 km of either Savannah, Georgia, or Wilmington, North Carolina, during the years 1851–2018. Return periods for tropical cyclones are longer for Savannah than for Wilmington, particularly for intense hurricanes. Intense GOM hurricanes are weakened by land interaction, which would result in longer return periods. A secondary maximum in the number of tropical storms early in hurricane season is more pronounced with proximity to the Gulf of Mexico, which is again consistent with the contribution from GOM tropical cyclones. Moreover, the percentage of tropical cyclones that passed near Savannah but did not make landfall is higher than that for Wilmington, again an indication of the significance of GOM tropical cyclones. Further evidence of the influence of GOM tropical cyclones is seen in the difference in approach angle and translational velocity between tropical storms and hurricanes. In addition, translational velocities for tropical cyclones increase with latitude, and translational velocities for tropical cyclones near either Savannah or Wilmington increase as the hurricane season progresses. Both relationships are likely due to the interaction of tropical cyclones with synoptic and planetary-scale winds. The median date for tropical cyclones has shifted earlier in recent decades for both Savannah and Wilmington, which is potentially an indication of climate change. An improved understanding of the climatology of tropical cyclones could lead to enhanced city planning, building codes, infrastructure, and resource management. [ABSTRACT FROM AUTHOR]

Lindner, B.L., Climatology and variability of tropical cyclones affecting Charleston, South Carolina, from 1670 to 1850. Journal of Coastal Research, 35(2), 397–409. Coconut Creek (Florida), ISSN 0749-0208. An improved understanding of the climatology of tropical cyclones helps communities plan for their consequences. Many industries and governmental agencies base risk assessment analysis and cost–benefit analysis upon the frequency of tropical cyclones of varying intensity. The inclusion of earlier periods lengthens the baseline of the climatological data and thus improves frequency estimates, but it also increases the uncertainty therein. To reduce this uncertainty, a limited meta-analysis combined seven previous historical studies to infer the properties of the 78 tropical cyclones that affected Charleston, South Carolina, during the period 1670–1850. Return rates for hurricanes are estimated at 5.2 and 3.8 years for the periods 1670–1850 and 1778–1850, respectively (the latter period is better documented), although uncertainties in the historical record result in large uncertainties in the return rates. Key observations for significant tropical cyclones were used to distinguish those that were likely to have been major hurricanes. The estimated return rate of 12 years for major hurricanes is likely inconsistent with prior studies that show an increasing number of major hurricanes in the modern era in the broader Atlantic Ocean, potentially because of climate change. The period 1778–1850 likely had a return rate of 9 to 10 years for major hurricanes in Charleston, which implies this may have been a particularly active period. The seasonality of tropical cyclones for the period 1670–1850 in Charleston is similar to the seasonality of tropical cyclones in the modern era, except that the median date for major hurricanes is likely significantly earlier during the period 1670–1850. Finally, the apparent lack of a change in the length of the tropical cyclone season over the past three centuries may be inconsistent with prior studies that show climate change may be inducing a seasonal broadening in the nearby Atlantic Ocean. [ABSTRACT FROM AUTHOR]

Kobashi, D. and Jose, F., 2018. Potential impacts of sand mining on hydrodynamics and fine sediment suspension and deposition on an inner-shelf shoal. In: Almar, R.; Almeida, L.P.; Trung Viet, N., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 76–85. Coconut Creek (Florida), ISSN 0749-0208. Wave and hydrodynamic models are implemented to investigate whether sand mining on a transgressive sand shoal could influence hydrodynamic processes and sedimentary environment of the shoal covered with fine sediments. An effort is made to evaluating shoal hydrodynamic response to a hypothetical dredging scenario under a host of probable storm conditions. The model results show that changes in hydrodynamic and sedimentary environment strongly depend on the storm conditions and the shoal bathymetry. Wave dissipation, flow conditions and sediment re-suspension are significantly higher on the shallower western shoal and gradually decrease toward the deeper eastern section of the shoal. The finding suggests that the deeper eastern shoal can be exposed to frequent deposition of fine sediments, as opposed to the western shoal, despite its location farther away from the nearby major river mouth. It is concluded that large-scale sand mining, in particular from the shallower western shoal, is expected to profoundly alter the hydrodynamics and sediment suspension and deposition processes, which may also influence the benthic ecology of the shoal. The mining from the deeper eastern shoal may result in lesser impacts than the mining from the ecologically sensitive western shoal. [ABSTRACT FROM AUTHOR]

ABSTRACT Lindner, B.L. and Neuhauser, A., 2018. Climatology and variability of tropical cyclones affecting Charleston, South Carolina. Communities benefit from site-specific examinations of tropical cyclone climatology. The impact data from a tropical cyclone climatology are useful for planning purposes for emergency managers, medical facilities, building and infrastructure codes, utility and communications design, insurance, and wildlife and resource management. To that end, per an analysis of National Hurricane Center data for the years 1851 to 2015, a chronological list of tropical cyclones that passed within 139 km (75 nautical miles) of Charleston, South Carolina was compiled. Date, intensity, approach angle, and translational velocity were catalogued for each system upon closest approach. The return period is approximately 1.5 years for tropical storms and hurricanes, 3.8 years for hurricanes, and 28 years for major hurricanes. The frequency of zero-strike and multistrike seasons is well reproduced by a Poisson distribution, implying random strikes. The seasonality of tropical cyclones in Charleston shows a secondary maximum early in the hurricane season, likely due to the numerous diminished tropical cyclones that originated in or passed through the Gulf of Mexico. In fact, there has been an increase in recent decades in the occurrence of early-season tropical cyclones. The large fraction of tropical cyclones that affect Charleston after originating in or passing through the Gulf of Mexico can also be seen in the data for approach angle (most strikes by tropical storms were by those that came over land) as well as in the data for translational velocities (higher for tropical storms than for hurricanes). Charleston not only experienced more tropical cyclones during the years 1871–1910, but these cyclones also had higher-than-average translational velocities at closest approach. [ABSTRACT FROM AUTHOR]

Tropical cyclone track, landfall central pressure, accumulated cyclone rain, and storm surge are assessed for five stations surrounding Lake Pontchartrain in Louisiana: Shell Beach, the New Orleans Lakefront, Frenier, Mandeville, and Slidell. Floods from 1901-2012 are analyzed for cases in which the event tracks, the landfall central pressure, the amount of inland flooding from precipitation, and the storm-surge inundation all lead to compound effects, as in Hurricane Katrina (2005) and Hurricane Isaac (2012). Data are from U-Surge, the National Hurricane Center, and the National Weather Service Cooperative Observer Program. A storm track climatology is provided showing the average track for all events and for events that reached at least 43 m s-1. The intense storms have a more concentrated track and approach from the south. Correlation and multivariate linear regression were used to evaluate the relationship among landfall central pressure, accumulated rainfall, and storm surge. For every 1 mbar increase in pressure when rainfall was held constant, the storm surge decreased by 0.024 m (p value <0.000). For every 1 mm of increase in rainfall when pressure was held constant, the storm surge increased by 0.006 m (0.0001). These two variables explain 63% of the variability in storm surge at this station. A percentage of change analysis from quantile regression was used to understand the amount of change in the storm surge based on the amount of change in the rainfall or the landfall central pressure. A small change in rainfall amounts or landfall central pressure can lead to a large change in the storm surge. [ABSTRACT FROM AUTHOR]

Ghader, S.; Yazgi, D.; Haghshenas, S.A.; Razavi Arab, A., Jedari Attari, M., Bakhtiari, A., Zinsazboroujerdi, H., 2016. Hindcasting Tropical Storm Events in the Oman Sea. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1087 - 1091 Coconut Creek (Florida), ISSN 0749-0208. Reliable coastal structure design, sediment transport predictions and future planning all depend on the use of accurate long-term wave data. The present study aims to reproduce measured data from the most important tropical storms in the Oman Sea whose observational data are available. This is assumed as a part of a new wave/wind hindcast for a period of about 30 years over Iranian waters of the Oman Sea. In order to provide a reliable assessment of the wave conditions for this area, three tropical cyclone events are selected for the hindcast model, including Gonu (2007), Phet (2010) and Nilofar (2014). The wind field is reproduced using a meso-scale numerical weather prediction model, namely, Weather Research and Forecast (WRF) model. The reproduced wind field is introduced to the 3rd generation wave model SWAN to hindcast wave characteristics for the most sever event of the mentioned three storms, i.e. Gonu event. [ABSTRACT FROM AUTHOR]

Shaw, C.E. and Benson, L., 2015. Possible tsunami deposits on the Caribbean coast of the Yucatán peninsula. The western Caribbean Basin is notable for its tectonic stability. It has experienced no historical earthquakes or the tsunami that sometimes accompany them. This paper describes a single, wedge-shaped, boulder-covered, coastal berm on the Yucatán coast of México that stretches unbroken for 50 km across a coastal segment characterized by rocky headlands that alternate with crescent beaches. The remainder of the 350 km of Yucatán coast consists mostly of mangrove that extends 1 to 30 km inland, often behind long, sandy beaches. On the headlands, the surface of the berm is densely paved with boulders-large boulders on its seaward face and smaller boulders and cobbles on its gently sloping inland surface. The top of the berm reaches an elevation >4 m, above the reach of all but the largest modern storm waves. Berm sediments on the headlands consist of two distinct layers of unbedded coarse sand with numerous randomly distributed boulders and cobbles in the lower layer and a crudely textured gravel and sand layer above. At first glance the two layers appear to be separated by 20 cm of white sand above a thin, discontinuous zone of dark, greyish sand that contains isolated balls and smears of black organic material, apparently derived from a soil, or possibly leaf litter. The berm and its associated boulders track the modern coastal morphology in precise detail as it follows the form of modern headlands, bays, and transcoastal channels, indicating that deposition took place after development of the present coast. The berm sediments record two or three large waves, depending on whether the wave that deposited the boulder pavement is regarded as part of the second wave or as a separate wave. Radiocarbon dating indicates that at least one wave struck the coast approximately 1500 years before present. Minimum wave run-up exceeds 4 m above present sea level, and inland inundation reached 400 m along bays and transcoastal channels. The position and elevation of the berm, its lack of well-developed internal bedding, the paving of the berm surface by thousands of boulders, and its 400-m extent inland along channels and bays are features commonly associated with tsunami. However, some recent studies conclude that all of the features listed also can be produced by mega-hurricanes. Placed in the context of our literature search of the recent history of hurricanes and tsunami in the Caribbean Basin, we conclude that the single berm on the Yucatán coast represents an anomalous event for this area and that the berm sediments bear a strong similarity to descriptions of sediments from some historical tsunami and are unlike sedimentary features associated with historical hurricanes. [ABSTRACT FROM AUTHOR]

Huang, W.; Hagen, S.C.; Bacopoulos, P., and Teng, F., 2014. Sea-level rise effects on hurricane-induced salinity transport in Apalachicola Bay. Salinity is an important indicator for estuarine ecosystem. Estuarine salinity can be affected by hurricane and sea-level rises. In this study, hydrodynamic modeling study has been conducted to investigate the effects of sea-level rise on hurricane-induced salinity in Apalachicola Bay. By using the dataset for the Hurricane Dennis occurred in July, 2005, model simulations were conducted under different sea-level rise scenarios. Results from model simulations show the effects of sea-level rise on the estuarine salinity transport during different phases of the storm surge. Generally, the increase of water level by either storm surge or sea-level rise results in the intrusion of majority saline sea water from the east to the west through East Pass. Salinity at two oyster bars responds to the storm surge and sea-level rise differently because Cat Point is located in the east and Dry Bar is in the west of the river mouth. In Cat Point, sea-level rise can cause substantial increase of salinity because it is located between the river mouth and East Pass. Salinity at the peak of the storm surge reaches 30 ppt even without sea-level rise. While salinity at the end of the storm surge reduces to about 20 ppt under no sea-level rise condition at Cat Point, it substantially increases to 30 ppt in response to a sea-level rise of 0.2 m. However, in Dry Bar, salinity is less sensitive to the sea-level rise and the storm surge. At the peak of the storm surge, salinity in Dry Bar is 30 ppt, 28 ppt, 30 ppt., under SLR 0.2 m, 0.5 m, and 1.2 m, respectively. However, near the end of the storm surge, salinity is 22 ppt, 22 ppt, and 27 ppt under 0.2 m, 0.5 m, and 1.2 m SLR conditions, respectively. This indicates that, after the storm surge, salinity in Dry Bar can recover to the normal range (below 26 ppt) if sea-level rise is less or equal to 0.5 m. [ABSTRACT FROM AUTHOR]

Huang, W.; Hagen, S., and Bacopoulos, P., 2014. Hydrodynamic modeling of Hurricane Dennis impact on estuarine salinity variation in Apalachicola Bay. Hurricane Dennis made landfall in Florida on 10 July 2005 and caused a storm surge of 2.4 m in Apalachicola. Field observations of salinity, winds, and river inflows are available at a few stations in the bay during the hurricane event. Presented in this paper is a numerical modeling study that investigates the effects of Hurricane Dennis on estuarine mixing and transport. A previously calibrated three-dimensional (3D) estuarine hydrodynamic model was further validated by the field observations of salinity and water levels during the hurricane event. A large-scale storm-surge model was used to provide storm-surge hydrographs at the five estuarine boundaries for the 3D estuarine model. This model integration proved successful with the results indicating that the model predictions of storm-surge hydrographs and salinity match well with observations. Model predictions of spatial distributions of salinity and current fields are presented to demonstrate the fresh-saline water mixing at different times of the storm-surge event. Results indicate that the hurricane-induced storm surge caused substantial increase of salinity in the bay. Majority saline water entered the bay from the east during the storm surge event. Salinity at the oyster reef, Cat Point in the eastern bay area, is more sensitive to the increased water levels caused by storm surge than another oyster reef, Dry Bar, in the western bay area. [ABSTRACT FROM AUTHOR]

Shoreline surveys, high-resolution satellite imagery, aerial photography, and topographic maps were compiled using GIS and analyzed with the Digital Shoreline Analysis System to examine event- and decadal-scale patterns of shoreline movement related to tropical cyclone impacts on south Cedar Island, Virginia. Global Positioning System (GPS) shoreline surveys conducted on southern Cedar Island 1.5 months before and 3 weeks after Tropical Storm Ernesto in 2006 recorded shoreline movement that resulted from the storm. On average (arithmetic mean), the southern section of Cedar Island retreated 25.4 ± 1 m as a result of the storm. The most severe erosion was documented to the south of an ephemeral inlet where the shoreline retreated 54.8 m. Shoreline recovery in the study area was determined from a February 2007 aerial photoset and a June 2007 GPS shoreline survey. Between September 2006 and February 2007, the shoreline accreted an average of 7.4 ± 2.1 m. Between February 2007 and June 2007, the shoreline eroded an average of 0.2 ± 2.1 m. The comparison of the July 2006 (pre-Ernesto) and June 2007 (9 months after Ernesto) data revealed that the shoreline had not recovered to its poststorm position but rather had undergone net erosion averaging 18.3 ± 1 m. Additionally, the 155-year record (1852-2006) of Cedar Island shoreline retreat was compared with the historical record of tropical cyclones passing within 200 km of the Delmarva Peninsula. A marked acceleration in island retreat rates began in 1980 and continued until the end of the study period in 2007. This acceleration in island erosion rate coincided with an increased frequency of tropical cyclones within the studied region. [ABSTRACT FROM AUTHOR]

Tropical cyclone impacts on wetland, terrestrial, and shelf systems have been previously studied and reasonably delineated, but little is known about the response of coastal lakes to storm events. For the first time tropical cyclone impacts on a shallow coastal lake in the Louisiana coastal plain have been studied using direct lines of evidence. Using side-scan sonar, CHIRP subbottom, and echo sounder bathymétrie profiles, the lake bottom and shallow subsurface of Sister Lake was imaged pre- and post-Hurricanes Katrina and Rita to provide a geologic framework for assessing storm effects. Box cores were collected to provide site-specific "ground truth" data to further evaluate the accretion or erosion of sediment over the short storm period between synoptic geophysical surveys. X-ray radiographs of box cores showed clear increments of recent event sedimentation (1-10 cm in thickness), corroborated with radionuclide dating as being products of the storm period. High percentages of approximately 40% fine sand in the storm layer and its thickness relative to an average long-term sedimentation rate of 2.0 mm/y suggest that transport of storm-related sediments from the inner shelf is a large factor in Sister Lake sedimentation. This study provides a framework and fundamental understanding of lake bottom characteristics and impacts of storm-related physical processes on erosion, sediment resuspension, and deposition. For a general case of subsidence in the Louisiana coastal plain of 6-8 mm/y and future sea-level rise rate of at least 3 mm/y, the sediment deficit for Sister Lake is 7-9 mm/y, which suggests that Sister Lake will deepen and widen with time. [ABSTRACT FROM AUTHOR]

We studied the hydrodynamic response caused by the four major hurricanes that struck Florida's coasts in 2004; Charley, Frances, Ivan, and Jeanne. A large-scale, shallow-water-equation model was applied so as to simulate wind and tidally driven hydrodynamics from the deep ocean into the shelf and coastal waters of Florida. Hurricane Ivan served as the calibration case, where the adjusted parameter was the wind drag coefficient. We identified an "increased" wind drag coefficient to perform best and suggest it as a first approximation to the wave contribution to the hydrodynamics. The increased drag coefficient is offered to the consulting and/or forecasting communities, who are frequently without wave-modeling resources, as a pragmatic approach to approximate for waves. Hurricanes Charley, Frances, and Jeanne serve as the validation cases in which the increased wind drag coefficient was applied. Analysis was performed by inspection of maximum water-surface elevations, which are interpreted in terms of shelf and bay dynamics for the west coast hurricane cases (Charley and Ivan) and in terms of channel hydraulics for the east coast hurricane cases (Frances and Jeanne). We conclude that the broad shelf off Florida's west coast allows the storm tide to accumulate along the open coast and that the embayments further magnify the storm tide, and that the Atlantic Intracoastal Waterway along Florida's east coast is effective in propagating storm tide, where we show compartmentalization of the storm tide in the Indian River lagoon as caused by the flow impediment of the causeway abutments. [ABSTRACT FROM AUTHOR]

In spite of their preferential location inside tropical belts where extreme wave events occur, and in spite of their potential for rapidly lithifying coastal sediments and by doing so promoting their preservation, beachrocks have so far been poorly investigated for the record of tsunamis or storms. This contribution focuses on beachrock occurrences on the island of St. Bartholomew (French West Indies), which is located in a region at risk from such natural hazards. Geomorphic and sedimentologic criteria were used to characterize beachrocks from shores frequently exposed to extreme wave events. Besides known effects of waves on beachrocks, including exhumation and landward transport of broken slabs, this article reports less well-documented perturbations such as the immersion of beachrock layers and cementation of event deposits. During recent hurricanes, unlithified sands flooring beachrock slabs were washed away by highly turbulent flows, causing the collapse, fragmentation, and displacement of an 80 m long beachrock from the intertidal zone to the subtidal zone between -2m and -3m below mean sea level, with broad preservation of its characteristic orientation parallel to the shoreline. This example shows that, in regions subject to episodic extreme waves, submerged beachrocks might not be good indicators of past low stands of the sea because of the possibility they could have been dislocated from their primary intertidal setting. Using the magnitude of taphonomic imprint on reef-derived coarse clasts and their host sediments, rapid-burial event deposits and reworked event deposits cemented in beachrocks have been distinguished. The former represent high- energy wave sediments produced during a single short-lived event that could be a tsunami followed by permanent burial and rapid cementation; the latter contain coarse clasts produced during one or, more likely, multiple catastrophic events, and whose burial and cementation were delayed, thereby promoting their alteration and integration in time-averaged sediments, i.e., sediments produced during different time intervals but deposited together. This distinction is important for coastal-hazard risk assessments because establishing extreme event frequencies by dating event deposits must rely on single rather than composite events. The data collected during this investigation add to our understanding of the signature of extreme waves in beach systems undergoing early cementing processes, and by extension, their counterparts in the fossil record. [ABSTRACT FROM AUTHOR]

Short-term effects of two consecutive hurricanes on physical, chemical, and biological factors were examined in a Louisiana coastal lagoon (Bay Champagne) with a focus on effects to basal food resources. Hurricanes Gustav and Ike made landfall on Louisiana's coast on 1 and 13 September 2008, respectively. Water column and sediment chlorophyll a (Chl a), phytoplankton, and benthic microalgal (BMA) community composition, phytoplankton toxin production, sediment organic matter (SOM), sand :mud ratio, and water column nutrients were measured at one prehurricane and three posthurricane sampling dates. Additional samples were taken 1 year later to address relative long-term effects on sediment characteristics. After Hurricane Gustav, the sand :mud ratio of sediment significantly increased, whereas SOM and water depth decreased likely because of sediment transport of the beach and nearshore sands. This continued after the storm because of multiple breaches in the beach. Water column Chl a decreased over time; sediment Chl a did not significantly change. Phytoplanktonic diatoms increased in sediments after hurricanes relative to benthic assemblages, resulting in a BMA community more closely resembling the water-column phytoplankton community. The sand :mud ratio remained high for most stations, whereas SOM decreased after Gustav and remained low 1 year after the hurricanes. Thus, sediment nutritional quality decreased with decreases in SOM and reduced BMA species; however, phytoplankton may have replaced BMA as a food resource within sediments. Additionally, the abundance of phytoplankton in the domoic acid (DA)-producing genus Pseudo-nitzschia increased in the water column and benthos after the hurricanes, and particulate DA increased significantly in the water samples. Our results suggest that hurricanes substantially affect food resources (e.g., phytoplankton, BMA, and SOM) on Louisiana's coast, and posthurricane production of DA, in this case, could increase ecosystem stress during recovery. To our knowledge, this is the first study to address the effects of hurricanes on DA concentrations. [ABSTRACT FROM AUTHOR]

Some areas of the Texas coast along the Gulf of Mexico are stabilized by beach nourishment or artificial protections, but the northeast Texas coast has been damaged and changed by short- and long-period erosion. The berm or dune that can act as protection from wave activities rarely exists, and mild, sloping beaches increase the potential of erosion in the study area. The upper Texas coast was monitored by Texas A&M University between 1999 and 2005. The measured beach profiles showed the morphological short- and long-period changes by overwash, and critical erosion was observed, especially by the landfall of hurricane Rita in 2005. The suspected causes of severe erosion were analyzed by comparing dune heights and beach widths, and it was found that overwash was one of the major factors causing erosion of the shoreline in the area. When storms made landfall in neighboring regions, such as southern Texas, Louisiana, Mississippi, and Alabama, overwash by long-period waves of remote storms was observed during the beach surveys. Overwash by remote storms could not be ignored, and it was an important contributor to continued beach erosion in the study area. Erosion caused by direct landfall of storms had significant effects on long-period erosion as well. [ABSTRACT FROM AUTHOR]

Predicting the morphological impacts and associated hazards of extreme storms on barrier islands is facilitated by examining historical poststorm images and identifying the predominant alongshore and cross-shore patterns of erosion and deposition for different island segments. Morphological changes on the Mississippi-Alabama barrier-island chain produced by 12 Category 3 and stronger hurricanes since 1852 were analyzed to investigate whether barrier-island responses to extreme storms are controlled primarily by local geomorphic conditions or primarily by storm characteristics. Results of those analyses demonstrate that (1) antecedent topography and geomorphic conditions (island width, land elevations, nearshore bathymetry, subaqueous-boundary conditions) tend to exert greater control on local barrierisland impacts than storm parameters (path, intensity, wind speeds, water levels, shelf duration), and (2) types and alongshore patterns of storm overwash and island breaching are commonly repeated for the same island segments. Even when impact patterns are identical, magnitudes of sequential impacts, such as the inland distance of sediment transport, are unequal and are controlled by storm parameters (water levels, wind speeds) that influence wave heights, overwash-flow depths, and current velocities. [ABSTRACT FROM AUTHOR]

Studies of Lake Pontchartrain benthic invertebrates and submersed aquatic vegetation (SAV) from 1996 through 2005 provided the opportunity to determine community responses to severe disturbances including: recovery from shell dredging; effects of anoxia and hypoxia from saltwater intrusion; the 1997 Bonnet Carré Spillway opening; a prolonged drought resulting from an El Niño Southern Oscillation; and effects of Hurricane Katrina. We included reviews and updates of our recently published work, an integrated analysis of findings, and restoration recommendations. During this decadal study there were no prolonged periods of ''normal'' conditions. Instead, benthos and SAV were experiencing or recovering from significant temporal disturbances. This made it difficult to use the abundance of a particular set of organisms at a point in time to evaluate habitat quality or restoration success without considering past disturbance effects. Benthos species diversity and the relative abundance of stress tolerant groups such as annelids were good indicators of short-term adverse conditions, but rapid changes occurred in response to salinity and dissolved oxygen. Rangia cuneata was a good indicator of the extent of hypoxia and long-term damage from hurricanes. The distribution and abundance of SAV decreased with turbidity and nutrient increases, and Vallisneria americana and other freshwater SAV decreased with prolonged salinity increases. Resistance to and resilience after disturbances and natural changes during long term cycles have to be considered in evaluating habitat condition and restoration success. [ABSTRACT FROM AUTHOR]

Observations of hurricane impacts on coastal communities and predicted increases in tropical storm activity have spurred an interest in protection and restoration of coastal dunes. Dunes are valued for their role in the protection of infrastructure and aesthetic beauty. Past research on dune erosion has focused primarily on laboratory research or mathematical models. We directly assessed impacts of Hurricanes Ivan (2004) and Dennis (2005) on coastal dunes along Santa Rosa Island, a barrier island in the Gulf of Mexico. We recorded dune area for foredunes and secondary dunes, examined the spatial context of each dune, and recorded structural features of each dune before and after each hurricane. Both hurricanes severely impacted foredunes, and removal of foredune protection by Ivan led to severe impacts on secondary dunes from Dennis. Structural features of the dune, such as height and width, influenced resistance against storm-related erosion, but spatial context, such as location with respect to shoreline, also was important. Coastal dunes on this barrier island may be shifting to a state where their formation, recovery, and restoration are influenced heavily by tropical storm activity. The future success of coastal restoration efforts for maintenance of infrastructure or habitat protection should be cognizant of the importance of spatial context in addition to the structural and vegetation characteristics of dunes. [ABSTRACT FROM AUTHOR]

The effects of stochastic events on estuarine water quality parameters are often difficult to quantify spatially due to the inherent variability in these systems. The use of geographic information systems to identify spatial patterns and trends can improve such efforts. This work describes the use of geographic information systems and the Mantel Test to determine the existence of trends and the persistence of spatial patterns in the relationships between nutrients and chlorophyll a in an urbanized lagoonal estuarine system, Murrells Inlet, South Carolina. Relatively dry and wet periods were compared, the latter following several substantial precipitation events related to tropical hurricane activity in the summer of 1999. Dissolved inorganic nitrogen concentrations were elevated following the passage of Hurricane Irene, and chlorophyll a did not increase concomitantly. Orthophosphate was found to have persistently higher concentrations in the more urbanized regions of Murrells Inlet that were consistent spatially during the two sampling periods. Strong spatial and temporal correlations between chlorophyll a and dissolved silicate : dissolved inorganic nitrogen suggest a relationship between the latter ratio and the phytoplankton growth. However, there appeared to be only a tenuous relationship between chlorophyll a and dissolved inorganic nitrogen and phosphorus, both spatially and temporally, suggesting that nutrient requirements for phytoplankton growth were met by internal estuarine processes, during this time period. [ABSTRACT FROM AUTHOR]

The Coastal and Estuarine Storm Tide (CEST) model for the boundary-fitted curvilinear grid has been developed recently to simulate a hurricane-induced storm surge. A new wetting-drying algorithm was based on accumulated volume and was created for simulating overland flooding. To evaluate the capability of the CEST model, it was compared with the well-established storm surge model—Sea, Lake, and Overland Surge from Hurricane (SLOSH)—in model grid representation and surge inundation prediction. Two models were compared: first, by carrying out storm surge simulations for Hurricanes Andrew (1992), Hugo (1989), and Camille (1969) over SLOSH's coarse polar grids with cell sizes of 500-7000 m. Results show that the CEST model agreed better with field observations of storm surge flooding. The CEST model was further evaluated by applying it to a fine-resolution curvilinear grid, which has cell sizes of 100-200 m at the hurricane landfall area, along with a superior representation of coastal topography. Comparison of the model results with field-measured elevations of high water marks and the locations of debris lines indicated that the CEST model, with the use of a fine-resolution grid, greatly reduced the uncertainty in computing storm surge flooding. [ABSTRACT FROM AUTHOR]

Nutrient levels in coastal waters are significantly enhanced through atmospheric deposition. Bulk atmospheric deposition was sampled at 10 different sites throughout the Charleston Harbor watershed. Fluoride, chloride, phosphate, nitrate, and sulfate concentrations in the samples were determined with ion chromatography. Sulfate concentrations showed no statistically significant spatial variability. However, chloride and fluoride concentrations are found to be higher in samples from oceanside sites vs. the inland sites, presumably because of higher concentrations of sea spray aerosols. Samples from inland sites had higher concentrations of nitrates, presumably because of stronger influences of anthropogenic sources and continental dust aerosols. Samples from urban oceanside sites had higher fluoride, chloride, and nitrate concentrations than did samples from rural oceanside sites, suggesting an anthropogenic influence. Higher chloride and nitrate concentrations were noted in samples associated with Hurricane Opal. [ABSTRACT FROM AUTHOR]

Tropical cyclonic storm systems can have profound impacts on coastal plant communities both through direct mechanical damage and indirect factors, such as flooding or salt spray. Storms with high wind and low rainfall are especially likely to cause high salt spray accumulation on plants growing in close proximity to the ocean. I measured salt spray accumulation on a common coastal heathland plant species, Myrica pensylvanica, during normal growing-season conditions and following Tropical Storm Floyd. At both sampling times, salt spray accumulation was highest in areas closest to the ocean and salt decreased as distance from the ocean increased. Salt spray accumulation on leaves following the tropical storm was twice the salt spray accumulation during normal growing-season conditions. I also found higher necrosis on leaves following the tropical storm, particularly at distances farther from the ocean. These results suggest that even minor cyclonic storms could have an impact on coastal plants in New England through salt spray damage. [ABSTRACT FROM AUTHOR]

A simple model of the average swath of tropical storm and hurricane-force winds to the right and left of storm centers is developed and utilized to evaluate the geographical and temporal distribution of storm strikes at 'point locations' along the subtropical coast of the United States. The specific area of study is from South Padre Island, Texas, to Cape Hatteras, North Carolina. The time of record is 100 years from 1901 through 2000. The analysis illustrates the great geographical variability with high frequencies of tropical storm and hurricane strikes in southeastern Louisiana, southern Florida, and eastern North Carolina. Coastlines with lower frequency strikes are located along the western coastline of the Gulf of Mexico in southern Texas, the northeastern coastline of the Gulf in Florida from near Apalachicola southward to St. Petersburg, and especially along the South Atlantic coast from Daytona Beach, Florida, northward to the vicinity of Charleston, South Carolina. Temporal variability is great and significant, however, and with the exception of the northern Gulf Coast, most coastal sites have experienced pronounced clusters of strikes separated by tens of years with very few strikes. The occurrences of tropicalstorm and hurricane events over the Gulf of Mexico are related to LaNina, neutral, and El Nino seasons, but the clusters of strike events and longer runs of seasons with minimal activity cannot be explained on the basis of ENSO indices alone. Our findings have important implications for storm clusters and vulnerability prediction along coasts. [ABSTRACT FROM AUTHOR]

The impacts of Trade Wind intensification and moderate hurricanes onbeach sediment balance have been analysed from a study of time variations of the sediment volume of Bagasse Beach and its shoreface, on the island of Martinique (French West Indies). Field experiments (wavecharacteristics, longshore current velocity, bathymetric and topographic surveys) conducted at different time scales show a negative dry season sediment budget and a slightly positive annual budget for thismicrotidal beach. Volumetric variations computed for one day of Trade Wind intensification appear to represent about twice those for one dry season. This analysis reveals that the influence of moderate hurricanes (coastal wave heights less than 2.5 m) on the long-term (2 yr)sediment balance is weak. In order to compare these high-energy events, numerical simulations have been carried out. Comparison between moderate hurricane conditions and a Trade Wind intensification event shows that the latter is responsible for more important volumetric erosion by about 23%. At a daily scale, moderate hurricanes have a larger power of erosion, 40 m3 m-1 day-1 versus 28 m3 m-1 day-1 for a Trade Wind intensification event. However, hurricane waves last only a few hours to 2 days, while waves generated by Trade Winds last, on average, 3-4 days. This study clearly highlights the importance of Trade Wind intensification events on the short-term (order of days) evolution of this beach. [ABSTRACT FROM AUTHOR]

The Shore Protection Manual published by the U.S. Army Corps of Engineers in 1984 provides hurricane wave prediction techniques. On 27 September, 1998, Hurricane Georges moved into the northeast Gulf of Mexico. During this period, a network of 5 surface stations operated by the National Data Buoy Center recorded simultaneously atmospheric pressure and significant wave height and period. In addition, both satellite and aircraft measurements were obtained. All of these data sets were employed to evaluate the prediction techniques as provided in the Shore Protection Manual. It is shown that the radius of maximum wind as determined by the surface network is in good agreement with bothsatellite and aircraft measurements. The predicted significant wave height and period are also consistent with buoy measurements. Finally, in order to estimate the significant wave height away from the radius of maximum wind, the graphs in the Shore Protection Manual were digitized and incorporated into a linear regression analysis. Using twobuoys, one near the radius of maximum wind and the other away from it, this statistical method provides a reasonable agreement between prediction and measurement for practical applications. [ABSTRACT FROM AUTHOR]

Aerial photography indicates that sometime since the early 1970's, an emergent ridge of shell debris developed on a mudbank north of Calusa Key in Florida Bay. Coarse shell deposits on and within the Bay's shallow mudbanks are believed to be the product of transport during major storm events and subsequent winnowing. However, shell material from the ridge contains nuclear bomb 14C, supporting formation within the past 30 years and the last major hurricanes to influence Florida Bay were Donna and Betsy (1960 and 1965). Results from this study suggest that the Calusa ridge and other coarse shell depositsin Florida Bay can result from, 1) periodic seagrass mortality and wave-induced transport during frequent winter cold fronts and/or 2) mollusc blooms and subsequent burial. A survey of bottom types indicates that dense to intermediate beds of seagrass, mainly Thalassia testudinum (turtle grass), occur within the shallow basins of western Florida Bay and along the margins of Bay mudbanks. Wave measurements and modeling indicate that Thalassia along mudbank margins can reduce incoming wave energy by over 80%. Seagrass beds also host particularly dense populations of molluscs from periodic 'blooms' and are believed to be the major source of coarse sediments in the Bay. Thus, if bank-edge seagrass dies, sediments, including shell debris, become exposedand subject to greatly increased wave energy. Modeling indicates that winds typical of winter cold fronts in South Florida can produce near-bottom velocities and shear stress at a grass-free bank edge whichare sufficient to transport coarse carbonate grains. Shell layers found at depth in mudbank cores can also be explained by previous episodes of sediment accretion over mollusc-rich seagrass beds or grass bed mortality at the edge of a mudbank and shell transport during cold front passage. The latter implies that mortality of marginal seagrassbeds has occurred throughout the history of Florida Bay and that thehist [ABSTRACT FROM AUTHOR]

The Isles Dernieres barrier island chain provides the front line of protection for the Lower Terrebonne Estuary, Louisiana. Landfall of Hurricane Andrew on August 26, 1992 resulted in overwash of most of this island chain, thereby accelerating the erosional processes and altering the plant communities of the islands. Four zones were identified by the depth of overwash sands received (from >50 cm to <10 cm) to examine the factors affecting the colonization of vegetation following overwash. Within each zone a permanent transect and thirty permanent plots were established and sampled four times over two years for biotic and abiotic variables. A total of 32 plant species was identified, 30 of which were located in the zone with the highest loadings of sand. Over time this zone also had the greatest increases in species richness. The most important survivor and early colonizer of the highzone overwash was Spartina alterniflora. However, over time Spartinapatens became dominant. The other zones, receiving moderate to no sand deposits, differed greatly. The few species present in these zones(<7) were indicative of high salt marsh and salt pan habitats and were dominated by Spartina alterniflora throughout the study. Using multivariate analyses, biotic and abiotic variables were correlated. Thesoil variables representative of topographical elevation and soil salinity influenced plant community zonations on the Isles Dernieres. Soil fertility and herbivory were not dominant factors affecting vegetation establishment. Backbarrier marsh areas that received the greatest sand loadings are now characterized by dune and swale plant species, while areas that received low sand loadings are returning to a marsh community. [ABSTRACT FROM AUTHOR]

The magnitude of storm events is only one determinant of their geomorphic effects. The timing and sequence of storms and the initial conditions of the shoreline also exert important controls on the geomorphic impacts. Two category three hurricanes struck coastal North Carolina during the summer of 1996, Bertha in July and Fran in September, with similar wind velocities and storm surges in the Neuse River estuary. There was little evidence of wave attack on the faces of shoreline bluffs along the Neuse estuary following Bertha, but the same bluffs experienced retreat of three to 12 meters following Fran. The dominant long-term process of slope retreat is mass wasting. Bertha removed toeslope sedimentary aprons and woody debris, which absorbed the majority of the wave energy. Thus, when the second storm arrived, wavescame into direct contact with the unconsolidated bluffs and initiated slope failures by undermining the lower bluffs. The effects of the hurricanes illustrate the importance of event sequencing and initial conditions rather than energy or magnitude in determining shoreline response, and the important interactions between slope (mass wasting) and coastal processes in causing bluff retreat along the Neuse. [ABSTRACT FROM AUTHOR]

Hurricane Bob, a category 3 storm, made landfall on Cape Cod in August 1991, and its effects on watersheds and adjoining estuaries were detected in the ongoing studies being carried out as part of the Waquoit Bay Land Margin Ecosystems Research project. On land, Bob had onlyminor overall effects on forests; localized wind bursts did snap andbreak trees in small and widely scattered forest parcels. Wind stripped up to half the leaves of deciduous trees and many herbaceous plants on the watershed, and most remaining leaves were damaged by salt, so that by the end of Aug, Cape Cod forests were defoliated. Damaged growing tips of exposed trees were evident for several growing seasons. The salt exposure was followed by a burst of growth and bloom in some plants during Sep--Oct. Forest invertebrates were disturbed by the storm. Nests of hornets and wasps, for example, were apparently destroyed and the survivors became a serious pest problem: hospital records show a ten-fold increase in cases of wasp stings just after Bob. Populations of these insects did not return to earlier abundance for several years. Birds and mammals did not appear to have suffered muchdamage. Leaching of salt to soils released previously-adsorbed soil ammonium. Such loss of critical nitrogen may be in part responsible for the characteristically dwarfed near-shore coastal forests, as wellas adds nitrogen to groundwater that in turn transports the nitrogento receiving waters. On the Bay, Bob thoroughly mixed the water column, but the stratification was restored within 1--2 days after passage of the storm. Short recovery times might be characteristic of shallow bays with short (2--3 d) water residence times. Bob opened a new inlet to Waquoit Bay, which remains open. The new inlet exerts only minor effects on circulation within the Bay, but did create localized damage to dune and eelgrass habitats near the new inlet. The mixing ofthe water column released major amounts of nutrients that were held within [ABSTRACT FROM AUTHOR]