Geology topics

Jennifer L. Miselis

Publications and source records attributed to Jennifer L. Miselis.

At least 19 recordsLinked to original sources

USGS2026

Barrier island geomorphic complexity drives storm and post-storm response

Barrier islands are at the forefront of climate-driven changes, with their resiliency threatened by rapid fluctuations in the physical drivers that shape them. Quantifying magnitudes and directions of storm-driven sediment fluxes and rates and modes of sediment recovery is essential for predicting barrier island trajectories. Yet scarce shoreface observations have limited such efforts. Here, shoreface-inclusive measurements of barrier sediment fluxes over five years following an extreme storm reveal distinct sediment redistribution patterns that vary with island geomorphology. Overwash fluxes were low compared with seaward fluxes, inlet-related landward transport, and previously modeled estimates. Without these observations, models may overestimate island elevation-building capacity that is key to sea-level adaptability. Post-storm recovery was incomplete despite human intervention, altering barrier sediment distribution from pre-storm conditions. This may increase vulnerability to future storms and rising water levels and suggests management approaches tailored to island geometry may better compete with climate change effects.

New York↗

USGS2026

Salt marsh establishment controlled by sediment availability, landscape position, and anthropogenic history

Anthropogenic actions have directly and indirectly modulated salt marsh extent globally. For example, direct actions such as draining and filling of marshes for agriculture were common before the early 20th century, while development on barrier islands has indirectly reduced the capacity of back-barrier marshes to evolve in response to coastal processes. Similarly, restoration efforts span a spectrum between direct actions such as hydrologic reconnection and sediment placement to indirect actions such as shoreline protection and facilitation of upland migration. With a combination of remote sensing and synoptic in-situ observations, we demonstrate that the vegetative establishment of two disparate salt marsh complexes are strongly linked to their access to external sediment supply, position in the coastal landscape, and anthropogenic history. A marsh complex fringing Delaware Bay, in a former agricultural reclamation area, was directly modified through re-introduction of tidal forcing; vegetative establishment occurred rapidly (3% y −1 increase in vegetative cover) due to a high flood-ebb suspended sediment differential (+32 mg l −1 ), indicating sediment import. The other marsh complex, behind a sand spit fronting the Atlantic Ocean, vegetated indirectly in response to updrift beach nourishment which provided a sheltered environment for expansion. The lower suspended sediment differential (+1.3 mg l −1 ) led to a slower vegetation establishment rate (1.7% y −1 ). The directly modified and restored complex responded more rapidly than the indirectly modified and restored complex due to sediment availability. Direct restoration may be more rapid than indirect methods, and reversing anthropogenic impacts is possible on relatively short timescales, if sufficient external sediment supply exists. Siting of restoration projects can therefore leverage external forcing to accelerate recovery and enhance resilience. In light of ongoing coastal transgression, these examples also demonstrate a potential difference in return-on-restoration-investment between back-barrier marshes undergoing coastal squeeze and estuarine fringing marshes that are naturally transgressing across the coastal landscape.

New Jersey↗

USGS2025

Modeling the influence of upper and lower shoreface dynamics on barrier island evolution

Barrier island resilience to climate impacts depends on sediment redistribution between the subaqueous shoreface and subaerial barrier during sea-level rise and storms. However, autogenic interactions between the upper and lower shoreface and their influence on the subaerial barrier are poorly characterized. Here, we explore the influences of various shoreface components on barrier morphology using a model of barrier and shoreface evolution under sea-level rise, the Articulated Barrier Shoreface (ABSF) Model. This reduced-complexity model divides the shoreface into upper and lower shoreface panels that respond independently to sea-level rise and deviations from the equilibrium slope. We couple the ABSF with the Lorenzo-Trueba & Ashton, 2014, https://doi.org/10.1002/2013jf002941 model (LTA), a barrier island evolution model driven by overwash and sea-level rise. Through this coupled framework, we examine the influences of upper and lower shoreface slopes, their respective depths, and sensitivity to wave climate on long-term barrier evolution. Results show that the relative depths of the upper and lower shoreface toes influence barrier response to rising seas, alongside overwash flux and closure depth. Notably, the lower shoreface response to sea-level change lags that of the upper shoreface over decades, diminishing the resilience of the barrier over centennial timescales by slowing the overall barrier response. In fact, the ABSF model predicts barriers will drown faster and more than predicted with a linear shoreface. Results highlight the shoreface as an important sediment reservoir for barrier islands and that differences in upper and lower shoreface responses can reduce barrier resilience to sea-level rise due to limited lower shoreface sediment accessibility.

JGR Earth Surface↗

USGS2025

Assessment of active sand volumes at Rockaway Beach and Fire Island in New York and Seven Mile Island in New Jersey

Between 2018 and 2023, the U.S. Geological Survey assessed shoreface sediment availability at three Atlantic Coast barrier island study sites in support of a National Fish and Wildlife Foundation project entitled, “Monitoring Hurricane Sandy Beach and Marsh Resilience in New York and New Jersey.” The three study sites are Seven Mile Island, New Jersey, Rockaway Beach peninsula, New York, and Fire Island, N.Y. Previously interpreted geologic boundaries from shoreface geophysical surveys and data from repeat bathymetric surveys at each of the study sites were integrated to quantify the active sediment volume, or the volume of sediment that could contribute to beach and shoreline behavior over annual to decadal time scales. This report describes the methods used to calculate these volumes and the variability of active sediment volume for each survey at the three study sites. Our data show that when shoreface volumes account for varying alongshore extent of each study site, Seven Mile Island and Rockaway Beach peninsula have about 1.5 times the active sediment volume measured at Fire Island.

New York, New Jersey↗

USGS2025

Geologic framework and Holocene sand thickness offshore of Seven Mile Island, New Jersey

The U.S. Geological Survey assessed the Quaternary evolution of Seven Mile Island, New Jersey, to quantify coastal sediment availability, which is crucial for establishing sediment budgets, understanding sediment dispersal, and managing coastlines. This report presents preliminary interpretations of seismic profiles, maps of Holocene sand thickness from the shoreline to 2 kilometers offshore, and tables quantifying the volume of available sediment along the coastal margin based on data collected during 2021 and 2022. The results reveal spatial variability in the thickness and cross-shore extent of Holocene sand. The study area was separated into northern, central, and southern zones by using underlying stratigraphy and geomorphic features. The characteristics and spatial extent of the Holocene sand deposit indicate that hydrodynamic processes contribute to its spatial variability. Northern Seven Mile Island contains the thickest deposits of Holocene sand that were formed by sediment bypass around the Townsends Inlet ebb-tidal delta. Specifically, swash bars have welded to the updrift end of Seven Mile Island and have formed thick deposits of Holocene sand that thicken landward and taper seaward. Despite their thickness, these deposits have the smallest cross-shore extent; therefore, northern Seven Mile Island has the smallest volume of Holocene sand of the three geomorphic zones. Central Seven Mile Island has the thinnest Holocene sand deposits because this section of the barrier island is outside the influence of ebb-tidal deltas. Southern Seven Mile Island has the greatest volumes of Holocene sand because of increased accommodation and deposition adjacent to the Hereford Inlet ebb-tidal delta. Even though tidal inlets exert variable influence on the three geomorphic zones, sediment is distributed fairly uniformly within each geomorphic zone; each of the three zones contains 31.05–36.48 percent of the volume of available Holocene sand.

New Jersey↗

USGS2024

Implications for the resilience of modern coastal systems derived from mesoscale barrier dynamics at Fire Island, New York

Understanding the response of coastal barriers to future changes in rates of sea level rise, sediment availability, and storm intensity/frequency is essential for coastal planning, including socioeconomic and ecological management. Identifying drivers of past changes in barrier morphology, as well as barrier sensitivity to these forces, is necessary to accomplish this. Using remote sensing, field, and laboratory analyses, we reconstruct the mesoscale (decades–centuries) evolution of central Fire Island, a portion of a 50 km barrier island fronting Long Island, New York, USA. We find that the configuration of the modern beach and foredune at Fire Island is radically different from the system's relict morphostratigraphy. Central Fire Island is comprised of at least three formerly inlet-divided rotational barriers with distinct subaerial beach and dune–ridge systems that were active prior to the mid-19th century. Varying morphologic states reflected in the relict barriers (e.g., progradational and transgressive) contrast with the modern barrier, which is dominated by a tall and nearly continuous foredune and is relatively static, except for erosion and drowning of its fringing marsh. We suggest that this state shift indicates a transition from a regime dominated by inlet-mediated gradients in alongshore sediment availability to one where human impacts exerted greater influence on island evolution from the late 19th century onward. The retention of some geomorphic capital in Fire Island's relict subaerial features combined with its static nature renders the barrier increasingly susceptible to narrowing and passive submergence. This may lead to an abrupt geomorphic state shift in the future, a veiled vulnerability that may also exist in other stabilized barriers.

New York↗

USGS2024

Unlearning Racism in Geoscience (URGE): Summary of U.S. Geological Survey URGE pod deliverables

The U.S. Geological Survey (USGS) is in a unique position to be a leader in diversity, equity, inclusion, and accessibility in the Earth sciences. As one of the largest geoscience employers, the USGS wields significant community influence and has a responsibility to adopt and implement robust, unbiased policies so that the science it is charged to deliver is better connected to the diverse communities it serves. Meaningful and effective improvements in implementation of diversity, equity, inclusion, and accessibility principles made within the USGS will be seen across the geoscience community. Despite this opportunity, however, the community, including the USGS, has struggled to diversify the geoscience workforce, which does not reflect the Nation’s diversity. This disparity suggests that the implementation of past policies did not achieve their desired outcomes in sustainable ways. The persistent lack of diversity across the geosciences and the racial justice protests of 2020 motivated a group of geoscience scholars to launch a global, virtual initiative known as Unlearning Racism in Geoscience (URGE) in the winter of 2021. The 16-week facilitated URGE curriculum was designed to highlight existing literature, share expert opinions, and foster discussion within groups (pods) around the world to build action plans for affecting change within their home institutions ( https://urgeoscience.org/ ). Whereas most of the approximately 4,500 participants were university faculty and students or from professional societies and nonprofit organizations, 6 pods totaling over 120 participants from the USGS joined the program—the largest participation of any Federal science agency. Summarizing the recommendations of over 100 USGS employees across the USGS who participated in URGE, this Circular represents a grassroots plan for making the USGS workforce more diverse and inclusive. To identify how peer-reviewed best practices could be implemented at the USGS, participants read existing literature, reviewed USGS policies and procedures, explored new and existing demographic data, and listened to and discussed primary interviews with scholars, all facilitated by the URGE program. This Circular leverages the efforts and momentum of the USGS URGE participants to catalyze and support positive, systemic change throughout the organization in a holistic way that represents an achievable departure from past policies that fell short of success. These recommendations are starting points. Reflecting the overall lack of diversity in the USGS workforce, the USGS URGE participants were predominantly White, meaning recommendations in this document can and should continue to evolve to include the lived perspectives and input from the broader USGS community. Finally, this summary document only highlights some of the key findings of these working groups. Additional details that may be more suitable to specific USGS Centers and programs can be found in the primary documents developed by each USGS URGE pod; a list of all registered pods can be found at https://urgeoscience.org/pods/ .

Circular↗

USGS2023

Reconstructing the geomorphic evolution and sediment budget history of a dynamic barrier island: Anclote Key, Florida

Decadal to centennial variations in sediment availability are a primary driver of coastal change within barrier systems. Models help explore how barrier morphology relates to past changes in magnitude of sediment availability, but this requires insights and validation from field efforts. In this study, we investigate the progradation of Anclote Key via its morphostratigraphy, a presently dynamic barrier on the Central Florida Gulf Coast. The results of our field efforts, including vibracores, ground-penetrating radar scans, and optically stimulated luminescence dating of sediments, reveal that Anclote Key has gone through at least two phases of sustained island-scale progradation, with an intervening episode of transgression followed by relative stability. We show that these shifts were likely driven by relatively small changes in shoreface sediment availability owing to the island’s limited accommodation and suggest that Anclote Key may have been relatively isolated from the alongshore sediment supply of nearby barriers prior to the late 20 th century.

Florida↗

USGS2023

Contributions to uncertainty in runup forecasts

The U.S. Geological Survey (USGS) provides operational forecasts of total water levels (TWL) and coastal change. Uncertainties around forecast TWL are based on the temporal and spatial range of observed beach slopes near the forecast site. This paper investigates other sources of uncertainty that are not accounted for, focusing on four beaches where the USGS has deployed remote cameras, and on outer Cape Cod, which has diverse bar morphologies. We find that the range of runup indicated by ten formulae is nearly as large as the variations caused by the range of beach slopes. A formula that accounts for bar morphology substantially decreases calculated runup, and might improve forecasts. Errors in the timing of forecast storm landfall generate uncertainties in TWL where tides are large. Analyses suggest that the effect of off-normal incident waves is relatively small. These results suggest opportunities for improving the TWL forecasts.

Massachusetts↗

USGS2023

Exploring centennial barrier-inlet evolution: Insights from undeveloped and developed phases at Barnegat Inlet, New Jersey

This study aims to identify the natural processes and the subsequent responses to coastal engineering and development on the alongshore evolution of the IB-BI-LBI inlet-barrier system. The primary focus will be the quantification of barrier island and inlet sediment partitioning at decadal to centennial timescales, from 1839-1941. We analyze historical alongshore evolution and track coastal engineering efforts at the Island Beach–Barnegat Inlet–Long Beach Island, NJ barrier-inlet system, which has transitioned from natural to highly developed over the past 180 years. We build a quantitative mass-balance framework that tracks sediment reservoir volumes and transport fluxes within the barrier-inlet system to describe both the natural and developed alongshore evolution of this system. We find that minor coastal engineering efforts, including the construction of small-scale wood and stone jetties, not only shift sediment transport locally, but also shift system-wide sediment transport based on inlet-barrier island interactions and sediment partitioning. Better understanding these different modes of past evolution can help to guide coastal management strategies as beach nourishment increases in cost, sea level-rise accelerates, and extreme storm patterns change.

New Jersey↗

USGS2023

Incorporating wave climate complexity into modeling lower shoreface morphology and transport

The lower shoreface, a transitional subaqueous region extending from the seaward limit of the surf zone to beyond the closure depth, serves as a sediment reservoir and pathway in sandy beach environments over annual to millennial time scales. Despite the important role this region plays in shoreline dynamics, the morphodynamics of the lower shoreface remain poorly quantified and understood. To better understand controls on shoreface morphology, here we combine energetics-based suspended sediment transport formulae (Ortiz & Aston 2016) with empirical wave climate data to incorporate temporal complexity in modeled equilibrium profiles and sediment flux rates. The equilibrium shoreface shape computed using a full wave climate is steeper in shallower water and less steep in the deeper reaches compared to profiles computed using single wave characteristics. Using a full wave climate to simulate steady-state morphology will yield steeper profiles in shallow water. Suspended sediment transport rates also vary in direction and magnitude at different equilibrium profile depths and can potentially inform the location of morphodynamic boundaries in the shoreface. Our results reveal how infrequent storm waves affect shoreface slopes, with large events tending to drive sediment onshore in the deeper portions of the profile. This work explores a few ways to add complexity to simple energetics-based frameworks to reproduce empirical bathymetric data more accurately and provides insight toward refining coastal source-to-sink models.

Conference Paper↗

USGS2023

Shoreface sediment availability offshore of a rapidly migrating, mixed-energy barrier island

Less is known about sediment exchanges between shorefaces and mixed-energy barrier islands (MEBI) than between shorefaces and wave-dominated barrier islands. We used seismic stratigraphy from Cedar Island, Virginia, USA to understand the interplay between shoreface deposits and MEBI morphodynamics. Interpretations reveal that the shelf and shoreface are extensively dissected by breach and inlet channels. Shoreface morphology varies due to underlying lithology and variable rates of barrier retreat. Underlying lithology adjacent to breach channels affected their migration rates, thereby exerting controls on alongshore extent of shoreface erosion. Shoreface deposits reworked by a migrating breach have lower slopes than those reworked by a more stationary one. Elevated rates of barrier retreat in southern Cedar Island may cause flattening of the shoreface because rapid barrier island migration required increased onshore sediment fluxes. In summary, barrier breach pervasiveness at MEBI may play an outsized role on shoreface ravinement and morphology. Ultimately, analyses of shoreface architecture and morphology provide insight on the relative influences of inlets, geology, and sea-level rise on barrier island sediment fluxes, which could help inform coastal planners, improve parameterization of shoreface sediment flux, and further future studies of morphologic change at MEBI.

Virginia↗

USGS2022

Undeveloped and developed phases in the centennial evolution of a barrier-marsh-lagoon system: The case of Long Beach Island, New Jersey

Barrier islands and their associated backbarrier environments protect mainland population centers and infrastructure from storm impacts, support biodiversity, and provide long-term carbon storage, among other ecosystem services. Despite their socio-economic and ecological importance, the response of coupled barrier-marsh-lagoon environments to sea-level rise is poorly understood. Undeveloped barrier-marsh-lagoon systems typically respond to sea-level rise through the process of landward migration, driven by storm overwash and landward mainland marsh expansion. Such response, however, can be affected by human development and engineering activities such as lagoon dredging and shoreline stabilization. To better understand the difference in the response between developed and undeveloped barrier-marsh-lagoon environments to sea-level rise, we perform a local morphologic analysis that describes the evolution of Long Beach Island (LBI), New Jersey, over the last 182 years. We find that between 1840 and 1934 the LBI system experienced landward migration of all five boundaries, including 171 meters of shoreline retreat. Between the 1920s and 1950s, however, there was a significant shift in system behavior that coincided with the onset of groin construction, which was enhanced by beach nourishment and lagoon dredging practices. From 1934 to 2022 the LBI system experienced ~22 meters of shoreline progradation and a rapid decline in marsh platform extent. Additionally, we extend a morphodynamic model to describe the evolution of the system in terms of five geomorphic boundaries: the ocean shoreline and backbarrier-marsh interface, the seaward and landward lagoon-marsh boundaries, and the landward limit of the inland marsh. We couple this numerical modeling effort with the map analysis during the undeveloped phase of LBI evolution, between 1840 and 1934. Despite its simplicity, the modeling framework can describe the average cross-shore evolution of the barrier-marsh-lagoon system during this period without accounting for human landscape modifications, supporting the premise that natural processes were the key drivers of morphological change. Overall, these results suggest that anthropogenic effects have played a major role in the evolution of LBI over the past century by altering overwash fluxes and marsh-lagoon geometry; this is likely the case for other barrier-marsh-lagoon environments around the world.

New Jersey↗

USGS2022

Geologic framework, anthropogenic impacts, and hydrodynamics contribute to variable sediment availability and shoreface morphology at the Rockaway Peninsula, NY

Recent field and modeling studies have shown that barrier island resiliency is sensitive to sediment fluxes from the shoreface, making it important to evaluate how shoreface sediment availability varies in coastal systems. To do this, we assessed shoreface geology and morphology along the Rockaway Peninsula, NY, USA. We find that spatial variability in shoreface volume is influenced by sediment accommodation above the Holocene-Pleistocene (H-P) contact, historical barrier island evolution, and natural and engineered morphologic features, suggesting that simply identifying the H-P boundary may not be adequate for defining the shoreface reservoir. Further, sediment flux from the lower shoreface to the beach may be reduced by geologically limited cross-shore sediment distribution and shoreface steepening mediated by human modifications to the shoreline. Finally, the geologic limit of the shoreface is often shallower than a wave-based estimate of shoreface extent, implying that the geologic shoreface extent at our study site can be mobilized over short time scales (years-decades) and that the wave-based shoreface extent may be inaccurate when estimating shoreline response to sea-level rise. Our results demonstrate that the combination of hydrodynamics, humans, and geology on shoreface sediment fluxes impact how barrier islands respond to future changes in sediment supply and climate.

New York↗

USGS2021

Shoreface and Holocene sediment thickness offshore of Rockaway Peninsula, New York

During September and October 2019, the U.S. Geological Survey mapped the shoreface and inner continental shelf offshore of the Rockaway Peninsula in New York using high-resolution chirp seismic reflection and single-beam bathymetry geophysical techniques. The results from this study are important for assessing the Quaternary evolution of the Rockaway Peninsula and determining coastal sediment availability, which is crucial for establishing sediment budgets, understanding sediment dispersal, and managing coastlines. This report presents preliminary interpretations of seismic profiles and maps of shoreface and Holocene sediment thickness from the shoreline to about 2 kilometers offshore. The results indicate that shoreface and Holocene sediment thickness demonstrates zonal variability because of underlying geology and sediment availability. Based on geomorphic features and underlying stratigraphy, the study area is separated into west, west-central, east-central, and east zones. Holocene sediment, which includes the shoreface and seafloor features with positive morphology (for example, nearshore bars, ebb-tide deltas, and sorted bedforms), thickens to the west and may be related to accommodation and westward dip of the regional unconformity. Shoreface units, which are thought to represent the active volume of littoral sediment, are thickest in the west-central peninsula where the geologic base of the shoreface is deeper. Shoreface units with moderate thickness are in the western and eastern peninsula where there are positive morphological features (for example, deposits accumulating updrift from the jetty, ebb-tide deltas, and so on). The thinnest shorefaces are in the east-central Rockaway Peninsula because of less accommodation caused by the shoaling regional unconformity.

New York↗

USGS2021

Satellite-derived barrier response and recovery following natural and anthropogenic perturbations, northern Chandeleur Islands, Louisiana

The magnitude and frequency of storm events, relative sea-level rise (RSLR), sediment supply, and anthropogenic alterations drive the morphologic evolution of barrier island systems, although the relative importance of any one driver will vary with the spatial and temporal scales considered. To explore the relative contributions of storms and human alterations to sediment supply on de-cadal changes in barrier landscapes, we applied Otsu’s thresholding method to multiple satel-lite-derived spectral indices for coastal land-cover classification and analyzed Landsat satellite imagery to quantify changes to the northern Chandeleur Islands barrier system since 1984. This high temporal-resolution dataset shows decadal-scale land-cover oscillations related to storm–recovery cycles, suggesting that shorter and (or) less resolved time series are biased toward storm impacts and may significantly overpredict land-loss rates and the timing of barrier mor-phologic state changes. We demonstrate that, historically, vegetation extent and persistence were the dominant controls on alongshore-variable landscape response and recovery following storms, and are even more important than human-mediated sediment input. As a result of exten-sive vegetation losses over the past few decades, however, the northern Chandeleur Islands are transitioning to a new morphologic state in which the landscape is dominated by intertidal envi-ronments, indicating reduced resilience to future storms and possibly rapid transitions in mor-phologic state with increasing rates of RSLR.

Louisiana↗

USGS2021

Impacts of sediment removal from and placement in coastal barrier island systems

Executive Summary On June 24, 2019, Congressman Raul Grijalva of Arizona, Chair of the House Committee on Natural Resources, sent a letter to the directors of the U.S. Fish and Wildlife Service and the U.S. Geological Survey to request their assistance in answering questions regarding coastal sediment resource management within the Coastal Barrier Resources System as defined by the Coastal Barrier Resources Act (Public Law 97–348; 96 Stat. 1653; 16 U.S.C. 3501 et seq.). For the purposes of this response, coastal sediment resource management refers to the removal of sediment from one part of a barrier island system for placement in another part of the coastal system, for either hazard mitigation (for example, erosion or flood control) or coastal restoration (for example, expansion or restoration of beach, dune, and [or] marsh habitats). The specific topics of concern are as follows (paraphrased from Congressman Grijalva’s letter): 1. Disruption of coastal sediment supply resulting from sediment removal and placement, including the replenishment rate of removed sediments and impacts to other components of the barrier island system (discussed in sec. 3). 2. Physical and biological impacts of sediment removal and placement on benthic habitats (discussed in sec. 4). 3. Impacts of sediment removal and placement on fish and other marine species (discussed in sec. 5). 4. Changes in migratory bird nesting and foraging habitats resulting from sediment removal and placement (discussed in sec. 6). 5. Long-term impacts of sediment removal and placement on physical coastal resiliency (discussed in sec. 7).

Open-File Report↗

USGS2021

Quantifying thresholds of barrier geomorphic change in a cross-shore sediment-partitioning model

Barrier coasts, including barrier islands, beach-ridge plains, and associated landforms, can assume a broad spectrum of morphologies over multi-decadal scales that reflect conditions of sediment availability, accommodation, and relative sea-level rise. However, the quantitative thresholds of these controls on barrier-system behavior remain largely unexplored, even as modern sea-level rise and anthropogenic modification of sediment availability increasingly reshape the world's sandy coastlines. In this study, we conceptualize barrier coasts as sediment-partitioning frameworks, distributing sand delivered from the shoreface to the subaqueous and subaerial components of the coastal system. Using an idealized morphodynamic model, we explore thresholds of behavioral and morphologic change over decadal to centennial timescales, simulating barrier evolution within quasi-stratigraphic morphological cross sections. Our results indicate a wide diversity of barrier behaviors can be explained by the balance of fluxes delivered to the beach vs. the dune or backbarrier, including previously understudied forms of transgression that allow the subaerial system to continue accumulating sediment during landward migration. Most importantly, our results show that barrier state transitions between progradation, cross-shore amalgamation, aggradation, and transgression are controlled largely through balances within a narrow range of relative sea-level rise and sediment flux. This suggests that, in the face of rising sea levels, subtle changes in sediment fluxes could result in significant changes in barrier morphology. We also demonstrate that modeled barriers with reduced vertical sediment accommodation are highly sensitive to the magnitude and direction of shoreface fluxes. Therefore, natural barriers with limited sediment accommodation could allow for exploration of the future effects of sea-level rise and changing flux magnitudes over a period of years as opposed to the decades required for similar responses in sediment-rich barrier systems. Finally, because our model creates stratigraphy generated under different input parameters, we propose that it could be used in combination with stratigraphic data to hindcast the sensitivity of existing barriers and infer changes in prehistoric morphology, which we anticipate will provide a baseline to assess the reliability of forward modeling predictions.

Earth Surface Dynamics↗