Back-barrier Bay Research Articles

Trends in the Climatology of Winter Wind Wave Heights in a Back-Barrier Bay in Western North Atlantic Ocean

Trends in the Climatology of Winter Wind Wave Heights in a Back-Barrier Bay in Western North Atlantic Ocean

Holocene morpho-sedimentary evolution of Marambaia Barrier Island (SE Brazil)

AbstractBarrier islands are sedimentary bodies susceptible to changes in sediment supply, dominant physical processes, and sea level. The aim of this work was to study the sedimentary processes that established Marambaia Barrier Island (SE Brazil) as an elongated sandy body that created Sepetiba Bay. For this purpose, barrier and back-barrier bay environments were analyzed using high-resolution satellite imagery, geophysical and topographic surveys, surface sediment samples and short cores, and radiocarbon and optically stimulated luminescence (OSL) dating techniques. Seven morpho-sedimentary domains were identified: coastal beach ridges, overland flow features, inter-ridge paleo lagoon, bayside beach ridges, marshlands, dune field and tidal wetlands. The results show that Marambaia Barrier Island evolved throughout the Holocene, first under normal regression conditions during sea-level rise, and then by forced regression as sea level lowered to its present position. Concurrent processes related to longshore drift, onshore transport, reworked barrier deposits, eolian transport, bay circulation, and pedogenesis influenced its morpho-sedimentary evolution. Morphological features such as truncated beach ridges, flying spits, and filled channels attest to the occurrence of alternating periods of erosion and accretion, evincing how the morphology of barrier island systems preserves an important archive of environmental changes.

Impacts of climate change on hurricane flood hazards in Jamaica Bay, New York

Sea level rise (SLR) and tropical cyclone (TC) climatology change could impact future flood hazards in Jamaica Bay—an urbanized back-barrier bay in New York—yet their compound impacts are not well understood. This study estimates the compound effects of SLR and TC climatology change on flood hazards in Jamaica Bay from a historical period in the late twentieth century (1980–2000) to future periods in the mid- and late-twenty-first century (2030–2050 and 2080–2100, under RCP8.5 greenhouse gas concentration scenario). Flood return periods are estimated based on probabilistic projections of SLR and peak storm tides simulated by a hydrodynamic model for large numbers of synthetic TCs. We find a substantial increase in the future flood hazards, e.g., the historical 100-year flood level would become a 9- and 1-year flood level in the mid- and late-twenty-first century and the 500-year flood level would become a 143- and 4-year flood level. These increases are mainly induced by SLR. However, TC climatology change would considerably contribute to the future increase in low-probability, high-consequence flood levels (with a return period greater than 100 year), likely due to an increase in the probability of occurrence of slow-moving but intense TCs by the end of twenty-first century. We further conduct high-resolution coastal flood simulations for a series of SLR and TC scenarios. Due to the SLR projected with a 5% exceedance probability, 125- and 1300-year flood events in the late-twentieth century would become 74- and 515-year flood events, respectively, in the late-twenty-first century, and the spatial extent of flooding over coastal floodplains of Jamaica Bay would increase by nearly 10 and 4 times, respectively. In addition, SLR leads to larger surface waves induced by TCs in the bay, suggesting a potential increase in hazards associated with wave runup, erosion, and damage to coastal infrastructure.

Morphological and Sedimentological Impacts of Hurricane Michael along the Northwest Florida Coast

Wang, P.; Adam, J.D.; Cheng, J., and Vallee, 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.

A numerical model investigation of the impacts of Hurricane Sandy on water level variability in Great South Bay, New York

Hurricane Sandy was a large and intense storm with high winds that caused total water levels from combined tides and storm surge to reach 4.0 m in the Atlantic Ocean and 2.5 m in Great South Bay (GSB), a back-barrier bay between Fire Island and Long Island, New York. In this study the impact of the hurricane winds and waves are examined in order to understand the flow of ocean water into the back-barrier bay and water level variations within the bay. To accomplish this goal, a high resolution hurricane wind field is used to drive the coupled Delft3D-SWAN hydrodynamic and wave models over a series of grids with the finest resolution in GSB. The processes that control water levels in the back-barrier bay are investigated by comparing the results of four cases that include: (i) tides only; (ii) tides, winds and waves with no overwash over Fire Island allowed; (iii) tides, winds, waves and limited overwash at the east end of the island; (iv) tides, winds, waves and extensive overwash along the island. The results indicate that strong local wind-driven storm surge along the bay axis had the largest influence on the total water level fluctuations during the hurricane. However, the simulations allowing for overwash have higher correlation with water level observations in GSB and suggest that island overwash provided a significant contribution of ocean water to eastern GSB during the storm. The computations indicate that overwash of 7500–10,000 m3s−1 was approximately the same as the inflow from the ocean through the major existing inlet. Overall, the model results indicate the complex variability in total water levels driven by tides, ocean storm surge, surge from local winds, and overwash that had a significant impact on the circulation in Great South Bay during Hurricane Sandy.

Tracking hurricane-generated storm surge with washover fan stratigraphy

Research Article| February 01, 2015 Tracking hurricane-generated storm surge with washover fan stratigraphy John Shaw; John Shaw * 1Department of Geosciences, 216 Ozark Hall, University of Arkansas, Fayetteville, Arkansas 72701, USA2Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA3Department of Geology and Geophysics, Department 3006, University of Wyoming, Laramie, Wyoming 82071, USA *E-mail: shaw84@uark.edu Search for other works by this author on: GSW Google Scholar Yao You; Yao You 2Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA †Current address: Hess Corporation, 1501 McKinney, Houston, Texas 77010, USA. Search for other works by this author on: GSW Google Scholar David Mohrig; David Mohrig 2Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar Gary Kocurek Gary Kocurek 2Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar Author and Article Information John Shaw * 1Department of Geosciences, 216 Ozark Hall, University of Arkansas, Fayetteville, Arkansas 72701, USA2Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA3Department of Geology and Geophysics, Department 3006, University of Wyoming, Laramie, Wyoming 82071, USA Yao You †Current address: Hess Corporation, 1501 McKinney, Houston, Texas 77010, USA. 2Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA David Mohrig 2Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA Gary Kocurek 2Jackson School of Geosciences, University of Texas at Austin, C9000, Austin, Texas 78712, USA *E-mail: shaw84@uark.edu Publisher: Geological Society of America Received: 14 Aug 2014 Revision Received: 18 Nov 2014 Accepted: 21 Nov 2014 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2014 Geological Society of America Geology (2015) 43 (2): 127–130. https://doi.org/10.1130/G36460.1 Article history Received: 14 Aug 2014 Revision Received: 18 Nov 2014 Accepted: 21 Nov 2014 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation John Shaw, Yao You, David Mohrig, Gary Kocurek; Tracking hurricane-generated storm surge with washover fan stratigraphy. Geology 2015;; 43 (2): 127–130. doi: https://doi.org/10.1130/G36460.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract We use the stratigraphy preserved in a washover fan to reconstruct the timing or emplacement and environmental conditions along the Matagorda Peninsula, Texas, during Hurricane Ike in 2008. Washover fan stratigraphy preserves a topset-foreset break (TFB) that rises 0.42 m in elevation as the fan built landward. We constrain overwash flow depths to 0.1–0.32 m through deposit sedimentology, and tie the rising trajectory of the TFB to rising storm surge water levels measured in the back-barrier bay (0.03 m h–1) as the hurricane approached the coast. This relation allows us to estimate that the fan took 0.52–0.90 days to build, and was finished building before the storm surge peaked. This is 15–25% of the 3.5 days of hurricane-induced storm surge near the site. We show how washover stratigraphy can be used to constrain the timing and amount of sediment redistribution on a coast associated with a hurricane; information that is necessary to test and/or calibrate existing numerical models that predict shoreline change during hurricanes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Interactions between barrier islands and backbarrier marshes affect island system response to sea level rise: Insights from a coupled model

AbstractInteractions between backbarrier marshes and barrier islands will likely play an important role in determining how low‐lying coastal systems respond to sea level rise and changes in storminess in the future. To assess the role of couplings between marshes and barrier islands under changing conditions, we develop and apply a coupled barrier island‐marsh model (GEOMBEST+) to assess the impact of overwash deposition on backbarrier marsh morphology and of marsh morphology on rates of island migration. Our model results suggest that backbarrier marsh width is in a constant state of change until either the backbarrier basin becomes completely filled or backbarrier marsh deposits have completely eroded away. Results also suggest that overwash deposition is an important source of sediment, which allows existing narrow marshes to be maintained in a long‐lasting alternate state (~500 m wide in the Virginia Barrier Islands) within a range of conditions under which they would otherwise disappear. The existence of a narrow marsh state is supported by observations of backbarrier marshes along the eastern shore of Virginia. Additional results suggest that marshes reduce accommodation in the backbarrier bay, which, in turn, decreases island migration rate. As climate change results in sea level rise, and the increased potential for intense hurricanes resulting in overwash, it is likely that these couplings will become increasingly important in determining future system behavior.

Tidal-Inlet Sediment Dispersal: ABSTRACT

Tidal inlets along the southeastern coast of the United States from Cape Hatteras to Cape Canaveral (the Georgia Bight) and along the North Sea coast from the Netherlands to Denmark (the German Bight) reflect a range in physical processes from wave dominance (at the flanks of the two bights) to tide dominance (at the center of the German Bight). Studies of the hydraulics, sediment dispersal, and historic morphologic changes of several inlets within the two bights have led to the identification of a continuum of inlet types from microtidal wave-dominated inlets at one end to macrotidal tide-dominated inlets at the other. The factors controlling the inlet types are: (a) the longshore sediment-transport rate caused by the momentum flux of the breaking waves, (b) the onshore- ffshore sediment-transport rate resulting from tidal currents, and (c) the flood-ebb asymmetry in tidal-current velocities. This last factor is determined by the hydraulic geometry of the back-barrier bay. The wave-dominated inlets have all their shoals on the bay side of the inlet throat. The mixed-energy inlets have shoals landward of, in, and seaward of the throat, and there is a distinct increase in the volume of the seaward shoals (ebb-tidal deltas) with increasing tide range. The tide-dominated inlets reflect situations where the longshore sediment-transport rate is completely subordinate to the onshore-offshore transport. In these situations, barrier islands cease to exist and tidally controlled lunate, sigmoidal, and linear sand bodies occur throughout the estuary entrance. End_of_Article - Last_Page 504------------

The Role of Waves and Tidal Currents in the Development of Tidal-inlet Sedimentary Structures and Sand Body Geometry: Examples from North Carolina, South Carolina, and Georgia

ABSTRACT Morphologic variability in tidal inlets along the southeastern coast of the United States has been considered with respect to the distribution of large-scale sand bodies, intertidal and subtidal bedforms and internal sedimentary structures. Data indicate that the morphologic variability in these inlets can be largely explained as a response to waves and tides. Other factors (tidal prism, inlet cross-sectional area and shape, the nature of the back-barrier bay, the degree of flood or ebb dominance, fresh water input, relative changes in sea level and sediment supply) exhibit lesser controls and their effects are less easily quantified. Three types of inlets are identified: tide-dominated, wave-dominated and transitional. 1) Tide-dominated inlets are characterized by a deep, ebb-dominant main channel flanked by long, linear channel-margin bars. Flood-tidal deltas are poorly developed or non-existent. Sand bodies landward of the inlet throat are confined to tidal point bars further landward in the marsh creek system. 2) Wave-dominated inlets are characterized by large, lobate flood-tidal deltas building into wide, open lagoons. The ebb-tidal delta is small and extends only a short distance from the beach. Tidal channels are generally shallow (less then 6 m) and often bifurcate landward and seaward of the throat. 3) In transitional inlets, major sand bodies are typically concentrated in the inlet throat. These inlets v ry widely in morphology and sand body geometry. Logically, this variability should be expressed in the rock record. In a vertical section through a tide-dominated inlet channel, a coarse base, overlain by bidirectional trough cross stratification from the deep channel and ebb-oriented, planar and trough cross stratification from the shallower channel should be expected. Swash-generated, horizontal plane laminations or slightly inclined accretion beds formed along the channel margins are less likely to be preserved. In contrast, a wave-dominated inlet sequence would contain primarily landward-oriented, planar and cross stratification from the shallower channel bottom, overlain by dominantly horizontal or slightly inclined plane laminations from the shallow channel sides. Transitional inlets would produce a variety of sequences, the xact nature of which would reflect the relative importance of waves and tides.

PROCESS-RESPONSE MODELS FOR DEPOSITIONAL SHORELINES: THE GERMAN AND THE GEORGIA BIGHTS

Sediment dispersal patterns in tidal inlets within the German and the Georgia Bights are found to be controlled by three major environmental factors: (1) the tide range, (2) the nearshore wave energy, and (3) the geometry of the backbarrier bay. Both embayments chosen for study are characterized by high wave energies and low tide ranges on their flanks, and low wave energies and high tide ranges in their centers. The spatial variability in inlet morphology, therefore, contains information on the relative role of tides and waves in inlet sediment dispersal. The paper concludes by proposing a simple model for inlet morphologies for successively greater relative role of tidal currents in the sediment dispersal.