Davis, R.A., 2013. A New Look at Barrier-Inlet Morphodynamics.

Coastal morphodynamics is dependent on the interaction of multiple variables. An earlier publication demonstrated that the comparative influence of waves and tides was the fundamental relationship in coastal morphology. The discussion in this paper adds the important variables of tidal prism, sediment abundance, and sea-level change to the equation. Tidal prism is critical in that it can be the primary factor in morphodynamics if both wave and tidal climate are held constant. Abundant or scarce sediment availability can produce coastal morphology that would not develop otherwise. Because of the extremely slow rate of sea-level change, its impact is less prominent than the other variables and we see less evidence of its influence than the others, except in certain coastal reaches.

Hayes, M.O. and FitzGerald, D.M., 2013. Origin, Evolution, and Classification of Tidal Inlets.

Tidal inlets are defined as major tidal channels separating individual barrier islands or barrier spits and adjacent headlands. Two types of barrier islands are recognized: (1) those that consistently migrate landward (transgressive), and (2) those that build seaward (prograding or regressive). The most common types include those that formed from (1) elongation of sand spits from major headlands; (2) drowning of coastal sand ridges; and (3) landward migrating transgressive barriers that stabilized and then prograded seaward during the mid-Holocene on the interfluves between the major lowstand valleys. Large tidal inlets developed in these former river valleys. The influence of tidal range vs. average wave height plays an important role in determining the morphology of the barrier islands and the character of the tidal inlets. As an example, the outer margins of the Georgia Bight, where the tidal range is microtidal and wave heights are greatest, most barrier islands are long (28–30 km), wave-dominated, and transgressive. Toward the mixed-energy head of the Bight, where the tidal range is mesotidal and waves are relatively small, barrier islands tend to be short (<15 km), regressive, and drumstick-shaped. Tidal inlets having large flood-tidal deltas are mostly restricted to the microtidal margins of the Bight, whereas inlets with large ebb-tidal deltas dominate the mesotidal head of the Bight. Most tidal inlets form by the following mechanisms: (1) storm-generated scour channels; (2) spit growth across the entrances to flooded valleys during the mid-Holocene; (3) intersection of major tidal channels by landward-migrating transgressive barrier islands; and (4) tidal prism-controlled, evenly spaced inlets that evolve in regions lacking major former river valleys.

Green, A.; Cooper, J.A.G., and LeVieux, A., 2013. Unusual barrier/inlet behaviour associated with active coastal progradation and river-dominated estuaries.

The mesoscale behaviour of unusual barrier inlets on the east coast of South Africa is described. The inlets are associated with river-dominated estuaries and are consequently subject to periodic closure during low river flow. They are also located on a prograding barrier coast. Deflection of the estuary channel of a small river in the direction of longshore transport by 1230 m resulted in its capture by the estuarine channel of a larger river. The larger catchment river was not deflected by coastal progradation but maintained its position by periodic breaching of a channel through the barrier during floods. Flood breaches reseal by landward reworking of ephemeral deltas and may undergo limited migration. A tidal inlet at the northern end of the barrier is maintained by a small tidal prism and has a flood-tidal delta. It exhibits limited lateral migration and closes occasionally when wave-generated sediment transport filling the channel overcomes the flushing ability produced by tidal currents and freshwater discharge by the river. Large swell waves and the development of a washover channel cause the occasional breaching of the barrier, creating an ephemeral inlet midway along the barrier. The position of this breach is likely controlled by wave refraction patterns.

Alexandrakis, G.; Ghionis, G., and Poulos, S. 2013. The effect of beach rock formation on the morphological evolution of a beach. The case study of an eastern Mediterranean beach: Ammoudara, Greece.

The present work investigates the decadal morphological evolution of a microtidal, perched beach and the effect that beach rock formations can have on coastal morphology. Using historical and recent morphological observations from Ammoudara Beach on the island of Crete, Greece, and numerical modeling, the interaction of beach rock formation and retreating coastline are investigated. The principal feature of the morphological evolution of the coastal zone under investigation has been the transformation of a beach rock formation, initially attached to the shoreface (1950s), to a submerged reef that is aligned subparallel to the present-day shoreline. At present, the beach rock is attached to the shoreface at sea level at the western part of the beach, but it has evolved to a submerged reef toward the east, being approximately 40 m off the shoreline at the central part and ∼70 m off the coastline at the eastern part of the beach. This kind of beach evolution is attributed to the interplay of natural hydrodynamic and sediment transport processes (that have been changing as the beach rock formation evolved to an offshore submerged reef) and to human intervention. The latter is exhibited mainly as changes in the sediment supply to the coastal zone (e.g., reduction in terrestrial freshwater/sediment influx, deterioration of sand dune field, and arbitrary abstraction of beach material). After a period of readjustment of the nearshore hydrodynamics to the changing morphology and vice versa, it seems that, at present, Ammoudara Beach has attained a new morphodynamic equilibrium where the shore-parallel reef acts as a submerged breakwater.

Kana, T.W.; Traynum, S.B.; Gaudiano, D.; Kaczkowski, H.L., and Hair, T., 2013. The physical condition of South Carolina beaches 1980–2010.

Thirty years of monitoring surveys and shoreline erosion studies (1980–2010) along the South Carolina coast show that artificial beach nourishment and the natural process of inlet shoal bypassing have advanced the shoreline along most of the developed beaches and barrier islands. Of the ∼98 mi (∼161 km) of developed beaches (including public parks), fully 80% were much healthier in 2010 than in 1980, as evidenced by burial of seawalls, wider berms, and higher dunes. About 15% of the developed beaches are in approximately the same condition as in 1980; the remaining ∼5% are considered in worse condition. The balance of South Carolina beaches (∼89 mi, ∼146 km) are principally wilderness areas with limited public access. The dominant condition of wilderness beaches is high erosion; limited new sand inputs, particularly via inlet bypassing; and accelerated recession as many of these sand-starved beaches wash over salt-marsh deposits. High erosion results from a combination of sand losses to the lagoon, winnowing of muddy marsh deposits outcropping across the receding beach, and longshore transport losses to the adjacent inlet. An estimated 75% of the undeveloped beaches in 2010 were well landward of their 1980 positions. Between 1980 and 2010, ∼39.4 million yd³ (∼30.1 million m³) of beach nourishment from external sources was added to developed and park beaches (∼62.6 mi, ∼102.6 km). This is equivalent to an addition of ∼168 ft (∼51 m) of beach width in the nourished areas. Natural shoal bypassing events appear to have added a similar magnitude of new sand along accreting beaches. Bypassing events at some beaches involved ∼2–5 million yd³ (1.5–3.8 million m³). Ebb dominance at many South Carolina inlets is shown to play an important role in preserving the littoral sand budget, maintaining large sand reservoirs for bypassing and helping maintain the developed beaches in the state. Low rates of erosion in other areas, such as the Grand Strand, combined with large-scale nourishment have advanced those beaches well beyond historic conditions.

Weathers, H.D. and Voulgaris, G., 2013. Evaluation of beach nourishment evolution models using data from two South Carolina, USA beaches: Folly Beach and Hunting Island.

Beach nourishment is a common method used for mitigating coastal erosion. However, it is also a costly undertaking and requires an appropriate cost-to-benefit analysis. Although the costs can be estimated relatively easily, the benefits are directly related to the life expectancy of the proposed project. With this in mind, three existing beach replenishment time-evolution models (the Linear Erosion, the Verhagen, and the One-Line models) were compared for their ability to represent data from two beach nourishment projects that have taken place in South Carolina, USA, at Folly Beach and Hunting Island. Another newly introduced model that combines the One-Line model with elements of the Verhagen model was also tested against the data from the beach nourishment projects. In addition to hindcast evaluation, the four models were employed to predict beach fill evolution at both locations, and those results were compared using the existing fill evolution data. Although all models provided a satisfactory statistical fit, the fitted parameter values from the Linear Erosion, the Verhagen, and the combined models failed to adequately describe physical processes associated with the development of each model. On the other hand, the One-Line model was able to describe beach fill volume evolution at both locations. The discrepancy between the models was exemplified in their application without the benefit of the statistical fitting. Overall, it was found that the One-Line model represented a more versatile approach to predicting volume losses because it is based on physical concepts of wave-induced sediment transport, and as such, it was better suited for use at any location as long as accurate information about the wave climate is available. Furthermore, detailed investigation at each site indicated that both the role of barrier island processes and the role of inlet dynamics in the evolution of beaches and beach fill were not fully recognized by the models and should be considered in the cost–benefit analysis of beach nourishment projects at barrier islands adjacent to ebb tidal deltas.

Scott, G.I.; Fulton, M.H.; DeLorenzo, M.E.; Wirth, E.F.; Key, P.B.; Pennington, P.L.; Kennedy, D.M.; Porter, D.; Chandler, G.T.; Scott, C.H., and Ferry, J.L., 2013. The environmental sensitivity index and oil and hazardous materials impact assessments: linking prespill contingency planning and ecological risk assessment.

The oil spill Environmental Sensitivity Index (ESI) was developed by Miles O. Hayes and researchers at Research Planning Institute and at the University of South Carolina during the 1970s and has been used by the National Oceanic and Atmospheric Administration (NOAA) to assess, forecast, and mitigate oil spill impacts throughout coastal regions of the United States. The ESI delineates different habitats types within coastal ecosystems and prioritizes their vulnerability to oil spills based on the persistence of oil and the ecological sensitivity of marine animals and plants within each habitat type. More physically exposed habitats (e.g., rock headlands), have shorter oil spill persistence and are less vulnerable than more sheltered habitats (e.g., tidal flats and salt marshes), where oil persists longer. Salt marshes are generally the most vulnerable habitats identified in most coastal regions of the United States using the ESI. To further assess impacts of oil and hazardous materials on salt marsh ecosystems, NOAA has developed a salt marsh mesocosm testing system that uses a modular approach to predict pollution impacts in the different marsh subhabitats, which are useful in defining multiple species toxicity and sensitivity to petroleum hydrocarbons and other chemical contaminants among the different salt marsh faunal taxa. The modular approach allows taxa in different salt marsh subhabitats, including Spartina alterniflora, Salicornia bigelovii, and Juncus roemerianus marsh communities, to be both individually and simultaneously compared and assessed. These mesocosms are also useful in predicting fate and effects, food web bioaccumulation, acute or chronic toxicity, and sublethal bioeffects for a number of pollutants. Results from these mesocosm studies indicate the utility of this integrated risk assessment method for predicting the fate and bioeffects of chemical contaminants on the estuarine salt marsh community and provide a direct link with the ESI, thus connecting prespill contingency planning and predictive ecological risk assessment.

Nixon, Z.; Michel, J.; Hayes, M.O.; Irvine, G.V., and Short, J., 2013. Geomorphic factors related to the persistence of subsurface oil from the Exxon Valdez oil spill.

Oil from the 1989 Exxon Valdez oil spill has persisted along shorelines of Prince William Sound, Alaska, for more than two decades as both surface and subsurface oil residues. To better understand the distribution of persistent subsurface oil and assess the potential need for further restoration, a thorough and quantitative understanding of the geomorphic factors controlling the presence or absence of subsurface oil is required. Data on oiling and geomorphic features were collected at 198 sites in Prince William Sound to identify and quantify the relationships among these geomorphic factors and the presence and absence of persistent subsurface oil. Geomorphic factors associated with the presence of subsurface oil were initial oil exposure, substrate permeability, topographic slope, low exposure to waves, armoring on gravel beaches, tombolos, natural breakwaters, and rubble accumulations. Geomorphic factors associated with the absence of subsurface oil were impermeable bedrock; platforms with thin sediment veneer; fine-grained, well-sorted gravel beaches with no armor; and low-permeability, raised bay-bottom beaches. Relationships were found between the geomorphic and physical site characteristics and the likelihood of encountering persistent subsurface oiling at those sites. There is quantitative evidence of more complex interactions between the overall wave energy incident at a site and the presence of fine-scale geomorphic features that may have provided smaller, local wave energy sheltering of oil. Similarly, these data provide evidence for interactions between the shoreline slope and the presence of angular rubble, with decreased likelihood for encountering subsurface oil at steeply sloped sites except at high-angle sheltered rubble shoreline locations. These results reinforce the idea that the interactions of beach permeability, stability, and site-specific wave exposure are key drivers for subsurface oil persistence in exposed and intermittently exposed mixed gravel beach and rocky shoreline environments.

Tye, R.S., 2013. Quantitatively modeling alluvial strata for reservoir development with examples from Krasnoleninskoye field, Russia.

Industry-accepted methods for estimating the subsurface dimensions of fluvial channel and channel-belt bodies were evaluated on their conceptual and physical bases. Geocellular models of fluvial reservoirs were built using several of these methods in conjunction with core and wireline-log data from the Krasnoleninskoye field, Russia. The objective was to use typical oil-field data and existing modeling technology to build geologically accurate geocellular models for field-development planning. Uncertainty in stratigraphic interpretation and geocellular modeling of fluvial reservoirs can be reduced by using floodplain deposits as pseudo-chronostratigraphic horizons to limit the miscorrelation of sandstone bodies, identifying and mapping paleovalleys constituting sandstone-prone fairways, and applying the physical relationships among maximum bankfull channel depth, channel width, and channel-belt width. A drawback to existing reservoir-modeling software is that it builds statistically based models conditioned to well data, but it does not incorporate physical-sedimentary laws. Therefore, reservoir zones in geocellular models must mimic paleovalley trends to prevent channel-body placement in a geologically inappropriate setting. Channels constrained by a geologically reasonable range of estimated dimensions (e.g., width, thickness, sinuosity) are distributed within the alluvial valleys along with the correct proportions of overbank-sandstone and floodplain deposits. Subsurface data interpreted from the standpoint of the physical-depositional processes they record, and with the recognition of the large- and small-scale sedimentation units comprising channel-bar and channel-fill strata, reveal how these strata vary from bar head to bar tail, and how the channel's geometry and migration style influenced the resultant vertical profile. Recognition of upper-bar deposits and their transition into natural-levee and/or floodplain deposits defines the maximum bankfull channel depth from which channel width and channel-belt width are estimated. Maximum bankfull channel depths of two Krasnoleninskoye fluvial reservoirs were estimated using core data in conjunction with thickness measurements based on wireline-log data. As a comparison, estimates of maximum bankfull channel depth were calculated based upon the relationships of cross-set thickness to dune height and dune height to flow depth using cross-set thicknesses measured in the cores. Estimated channel widths and channel-belt widths range by a factor of 2 to 5, depending upon the calculation method. Realizations of the Krasnoleninskoye fluvial strata show channel-body dimensions and channel-body morphologies comparable to the Santee River, South Carolina, alluvial valley, in which straight, meandering, and anastomosed channel reaches occur within a 4 by 11 km area. Thus, stochastic, but geologically realistic geocellular models of fluvial reservoirs are achievable if the model structure accurately defines alluvial valleys, valleys are populated with channel bodies appropriately sized by maximum bankfull channel-depth estimates, and one abandons the traditionally held belief that alluvial stratigraphy varies due to, and can be predicted from, the planform morphology of the river system from which it formed.

Pirkle, F.L.; Pirkle, W.A., and Rich, F.J., 2013. Heavy-mineral mining in the Atlantic Coastal Plain and what deposit locations tell us about ancient shorelines.

Economic mining of heavy-mineral sands has a long history in the Atlantic Coastal Plain. From the early part of the 20th century to date, a total of 11 heavy-mineral ore bodies either have been or currently are being mined in Florida and Georgia. Additional deposits have been lost to mining, primarily due to cultural events, or are waiting future exploitation. These deposits have different origins, as has been seen during recent evaluations of the deposits, some in contrast to conventional depositional models. It has long been believed that deposits formed along shorelines at the height of major marine transgressions, but it is now postulated that some heavy-mineral-bearing sands accumulated on regressional beach ridge plains during periods of temporary stillstands or during slight transgressions that accompanied general marine regressions. Although many deposits might indeed have formed as conventional beach placers, others might have accumulated as deposits associated with fluvial–deltaic regimes or with vegetational baffles. These different origins are reflected in the chemical and physical characteristics of the deposits as well as grain size of the sediment. The relationship of the heavy-mineral mineral deposits (location) to the landforms in the Atlantic Coastal Plain provides insight into the ancient shorelines of the Atlantic Coastal Plain.