ANALYZING HISTORICAL CHANGES TO TIDAL INLET AND TIDAL DELTA GEOMETRIES ALONG THE VIRGINIA BARRIER ISLANDS: A TEST OF THE RUNAWAY BARRIER ISLAND TRANSGRESSION MODEL

2017 ◽  
Author(s):  
Christine Johnson ◽  
◽  
Michael S. Fenster
Keyword(s):  
Barrier Island ◽  
Barrier Islands ◽  
Tidal Inlet ◽  
Historical Changes

How to link modern and ancient barrier island systems: Dimensional comparisons and updated sedimentary facies models 

2021 ◽  
Author(s):  
Cari Johnson ◽  
Julia Mulhern ◽  
Andrew Green
Keyword(s):  
Time Scales ◽  
Barrier Island ◽  
Barrier Islands ◽  
Sedimentary Facies ◽  
Thickness Measurement ◽  
Tidal Inlet ◽  
Lateral Migration ◽  
Geologic Time ◽  
Facies Associations ◽  
Facies Models

<p>Existing depositional and facies models for ancient barrier island systems are primarily based on modern observations. This approach overlooks processes tied to geologic time scales, such as multi-directional motion, erosion, and reworking, and their resulting expressions in preserved strata. We have investigated these and other challenges of linking modern and ancient barrier islands through outcrop studies and through data compilation from the rock record compared to modern barrier island dimensions. Results emphasize key depositional and preservation processes, and the dimensional differences between deposits formed over geologic versus modern time scales. For example, when comparing deposits from individual barrier islands, thickness measurement comparisons between modern and ancient examples do not vary systematically, suggesting that local accommodation and reworking dictate barrier island thickness preservation. A complementary outcrop study focusing on paralic strata from the Upper Cretaceous Straight Cliffs Formation in southern Utah (USA) is used to update models for barrier island motion and preservation to include geologic time-scale processes. Barrier island deposits are described using four facies associations (FA): backbarrier fill (FA1), lower and upper shoreface (FA2), proximal upper shoreface (FA3), and tidal channel facies (FA4). Three main architectural elements (barrier island shorefaces, shoreface-dominated inlet fill, and channel-dominated inlet fill) occur independently or in combination to create stacked barrier island deposits. Barrier island shorefaces record progradation, while shoreface-dominated inlet fill records lateral migration, and channel-dominated inlet fill records aggradation within the tidal inlet. Barrier islands are bound by lagoons or estuaries and are distinguished from other shoreface deposits by their internal facies and outcrop geometry, association with backbarrier facies, and position within transgressive successions. Tidal processes, in particular, tidal inlet migration and reworking of the upper shoreface, also distinguish barrier island successions. In sum, these datasets demonstrate that improved depositional and facies models must consider multidirectional island motion, ravinement, erosion, inlet migration, and reworking when describing processes and predicting barrier island dimensions.</p>

scholarly journals When Is a Barrier Island Not an Island? When It Is Preserved in the Rock Record

2021 ◽  
Vol 8 ◽  
Author(s):  
Julia S. Mulhern ◽  
Cari L. Johnson ◽  
Andrew N. Green
Keyword(s):  
Barrier Island ◽  
Barrier Islands ◽  
Tidal Inlet ◽  
Lateral Migration ◽  
Geologic Time ◽  
Architectural Elements ◽  
Straight Cliffs Formation ◽  
Facies Associations ◽  
Straight Cliffs ◽  
Facies Models

Existing barrier island facies models are largely based on modern observations. This approach highlights the heterogeneous and dynamic nature of barrier island systems, but it overlooks processes tied to geologic time scales, such as multi-directional motion, erosion, and reworking, and their expressions as preserved strata. Accordingly, this study uses characteristic outcrop expressions from paralic strata of the Upper Cretaceous Straight Cliffs Formation in southern Utah to update models for barrier island motion and preservation to include geologic time-scale processes. Results indicate that the key distinguishing facies and architectural elements of preserved barrier island systems have very little to do with “island” morphology as observed in modern systems. Four facies associations are used to describe and characterize these barrier island architectural elements. Barrier islands occur in association with backbarrier fill (FA1) and internally contain lower and upper shoreface (FA2), proximal upper shoreface (FA3), and tidal channel facies (FA4). Three main architectural elements (barrier island shorefaces, shoreface-dominated inlet fill, and channel-dominated inlet fill) occur independently or in combination to create stacked barrier island deposits. Barrier island shorefaces record progradation, while shoreface-dominated inlet fill records lateral migration, and channel-dominated inlet fill records aggradation within the tidal inlet. Barrier islands are bound by lagoons or estuaries and are distinguished from other shoreface deposits by their internal facies and outcrop geometry, association with backbarrier facies, and position within transgressive successions. Tidal processes, in particular, tidal inlet migration and reworking of the upper shoreface, also distinguish barrier island successions. In sum, this study expands barrier island facies models and provides new recognition criteria to account for the complex geometries of time-transgressive, preserved barrier island deposits.

scholarly journals Modeling Barrier Island Habitats Using Landscape Position Information

2019 ◽  
Vol 11 (8) ◽  
pp. 976
Author(s):  
Nicholas M. Enwright ◽  
Lei Wang ◽  
Hongqing Wang ◽  
Michael J. Osland ◽  
Laura C. Feher ◽  
...  
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Nearest Neighbor ◽  
Learning Algorithms ◽  
Barrier Island ◽  
Barrier Islands ◽  
Machine Learning Algorithms ◽  
Landscape Position ◽  
K Nearest Neighbor ◽  
Island Habitats

Barrier islands are dynamic environments because of their position along the marine–estuarine interface. Geomorphology influences habitat distribution on barrier islands by regulating exposure to harsh abiotic conditions. Researchers have identified linkages between habitat and landscape position, such as elevation and distance from shore, yet these linkages have not been fully leveraged to develop predictive models. Our aim was to evaluate the performance of commonly used machine learning algorithms, including K-nearest neighbor, support vector machine, and random forest, for predicting barrier island habitats using landscape position for Dauphin Island, Alabama, USA. Landscape position predictors were extracted from topobathymetric data. Models were developed for three tidal zones: subtidal, intertidal, and supratidal/upland. We used a contemporary habitat map to identify landscape position linkages for habitats, such as beach, dune, woody vegetation, and marsh. Deterministic accuracy, fuzzy accuracy, and hindcasting were used for validation. The random forest algorithm performed best for intertidal and supratidal/upland habitats, while the K-nearest neighbor algorithm performed best for subtidal habitats. A posteriori application of expert rules based on theoretical understanding of barrier island habitats enhanced model results. For the contemporary model, deterministic overall accuracy was nearly 70%, and fuzzy overall accuracy was over 80%. For the hindcast model, deterministic overall accuracy was nearly 80%, and fuzzy overall accuracy was over 90%. We found machine learning algorithms were well-suited for predicting barrier island habitats using landscape position. Our model framework could be coupled with hydrodynamic geomorphologic models for forecasting habitats with accelerated sea-level rise, simulated storms, and restoration actions.

scholarly journals Simulating barrier island response to sea level rise with the barrier island and inlet environment (BRIE) model v1.0

2019 ◽  
Vol 12 (9) ◽  
pp. 4013-4030 ◽  
Author(s):  
Jaap H. Nienhuis ◽  
Jorge Lorenzo-Trueba
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Barrier Island ◽  
Barrier Islands ◽  
Emergent Behavior ◽  
Tidal Inlets ◽  
Rise Rate ◽  
Ecological Importance ◽  
Alongshore Sediment Transport

Abstract. Barrier islands are low-lying coastal landforms vulnerable to inundation and erosion by sea level rise. Despite their socioeconomic and ecological importance, their future morphodynamic response to sea level rise or other hazards is poorly understood. To tackle this knowledge gap, we outline and describe the BarrieR Inlet Environment (BRIE) model that can simulate long-term barrier morphodynamics. In addition to existing overwash and shoreface formulations, BRIE accounts for alongshore sediment transport, inlet dynamics, and flood–tidal delta deposition along barrier islands. Inlets within BRIE can open, close, migrate, merge with other inlets, and build flood–tidal delta deposits. Long-term simulations reveal complex emergent behavior of tidal inlets resulting from interactions with sea level rise and overwash. BRIE also includes a stratigraphic module, which demonstrates that barrier dynamics under constant sea level rise rates can result in stratigraphic profiles composed of inlet fill, flood–tidal delta, and overwash deposits. In general, the BRIE model represents a process-based exploratory view of barrier island morphodynamics that can be used to investigate long-term risks of flooding and erosion in barrier environments. For example, BRIE can simulate barrier island drowning in cases in which the imposed sea level rise rate is faster than the morphodynamic response of the barrier island.

Salinity and the small-scale distribution of three barrier island shrubs

1994 ◽  
Vol 72 (9) ◽  
pp. 1365-1372 ◽  
Author(s):  
Donald R. Young ◽  
David L. Erickson ◽  
Shawn W. Semones
Keyword(s):  
Water Relations ◽  
Barrier Island ◽  
Barrier Islands ◽  
Small Scale ◽  
Similar Response ◽  
Groundwater Salinity ◽  
Baccharis Halimifolia ◽  
Myrica Cerifera ◽  
Interspecific Differences ◽  
Iva Frutescens

The importance of salinity to small-scale distribution patterns was examined for three shrubs common on barrier islands of the southeastern United States. Field measurements focused on the salt marsh – upland interface zone on Hog Island, Virginia, where Myrica cerifera, Baccharis halimifolia, and Iva frutescens form distinct distributional zones. Although considerable variation in salinity occurred throughout the growth season (June through October), total soil chlorides and groundwater salinity were lowest for M. cerifera, intermediate for B. halimifolia, and highest for I. frutescens. All three species showed similar diurnal and seasonal patterns in stomatal conductance and leaf xylem pressure potential, despite the differences in salinity. However, a laboratory experiment revealed interspecific differences in water relations when the three shrubs were exposed to identical salinity regimes. The field data and water relations experiment indicated M. cerifera is least tolerant to salinity, I. frutescens is most tolerant, and B. halimifolia is intermediate. Seed germination experiments revealed a similar response, except that B. halimifolia was more sensitive to salinity than M. cerifera. The interspecific differences in soil and groundwater salinity, along with the physiological response differences, indicated that salinity may be one of the major environmental factors influencing zonation among the three shrubs; however, the absence of I. frutescens and B. halimifolia in low salinity areas implied that other factors also influence zonation patterns on barrier islands. Key words: Baccharis halimifolia, Iva frutescens, Myrica cerifera, barrier island, salinity tolerance, shrub.

scholarly journals The Impact of Storm-Induced Breaches on Barrier Coast Systems Subject to Climate Change—A Stochastic Modelling Study

2020 ◽  
Vol 8 (4) ◽  
pp. 271 ◽  
Author(s):  
Koen R. G. Reef ◽  
Pieter C. Roos ◽  
Tessa E. Andringa ◽  
Ali Dastgheib ◽  
Suzanne J. M. H. Hulscher
Keyword(s):  
Nearest Neighbor ◽  
Morphological Evolution ◽  
Stochastic Modelling ◽  
Barrier Islands ◽  
Monte Carlo Analysis ◽  
Tidal Inlet ◽  
Degree Of Saturation ◽  
Tidal Inlets ◽  
The Creation ◽  
The Impact

Storms can have devastating impacts on barrier coasts causing coastal erosion, partial inundation, and possibly the breaching of barrier islands. The breaching of barrier islands provides a mechanism for the creation of new tidal inlets that connect the backbarrier basin (or lagoon) and the outer sea. As a new tidal inlet affects both the basin and the hydrodynamics of existing inlets, it is important to understand why an initial breach either closes or may evolve into a new tidal inlet. To this end, we performed a Monte Carlo analysis using an idealized model capable of simulating the long-term morphological evolution of multiple tidal inlets connected to a single backbarrier basin. To do so required the creation of a stochastic shell, as a new element around this existing barrier coast model. Our results demonstrate that barrier coast systems tend towards an equilibrium value for the number of inlets per kilometer of barrier coast and total inlet cross section. This even holds with the continuous stochastic forcing of storm-induced breaches. This finding implies that if a new breach opens in a coast that is already in equilibrium, existing inlets will shrink and may close if the new breach remains open. Furthermore, we find that climate-driven changes in storm frequency will modify the timescales in which barrier coasts reach their equilibrium state. Finally, we find that the distance between a new breach and its nearest neighbor is more important for its survival than the size of the breach or the degree of saturation of the barrier coast.

scholarly journals Statistical modeling of the long-range-dependent structure of barrier island framework geology and surface geomorphology

2018 ◽  
Vol 6 (2) ◽  
pp. 431-450 ◽  
Author(s):  
Bradley A. Weymer ◽  
Phillipe Wernette ◽  
Mark E. Everett ◽  
Chris Houser
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Long Range ◽  
Moving Average ◽  
Quantitative Measure ◽  
Barrier Island ◽  
Barrier Islands ◽  
Wave Number ◽  
Statistical Parameters ◽  
Padre Island

Abstract. Shorelines exhibit long-range dependence (LRD) and have been shown in some environments to be described in the wave number domain by a power-law characteristic of scale independence. Recent evidence suggests that the geomorphology of barrier islands can, however, exhibit scale dependence as a result of systematic variations in the underlying framework geology. The LRD of framework geology, which influences island geomorphology and its response to storms and sea level rise, has not been previously examined. Electromagnetic induction (EMI) surveys conducted along Padre Island National Seashore (PAIS), Texas, United States, reveal that the EMI apparent conductivity (σa) signal and, by inference, the framework geology exhibits LRD at scales of up to 101 to 102 km. Our study demonstrates the utility of describing EMI σa and lidar spatial series by a fractional autoregressive integrated moving average (ARIMA) process that specifically models LRD. This method offers a robust and compact way of quantifying the geological variations along a barrier island shoreline using three statistical parameters (p, d, q). We discuss how ARIMA models that use a single parameter d provide a quantitative measure for determining free and forced barrier island evolutionary behavior across different scales. Statistical analyses at regional, intermediate, and local scales suggest that the geologic framework within an area of paleo-channels exhibits a first-order control on dune height. The exchange of sediment amongst nearshore, beach, and dune in areas outside this region are scale independent, implying that barrier islands like PAIS exhibit a combination of free and forced behaviors that affect the response of the island to sea level rise.

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