Numerical modeling of the morphodynamic response of a low-lying barrier island beach and foredune system inundated during Hurricane Ike using XBeach and CSHORE

Harter, Craig; Figlus, Jens

doi:10.1016/j.coastaleng.2016.11.005

Cited by 72 publications

(52 citation statements)

References 23 publications

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“…Generally, the observed erosion and the landward transport of beach and beach crest during inundation agrees well with findings of dune erosion and transport to the back‐barrier part of the island during inundation by McCall et al () and Harter and Figlus (). While the seaward sediment transport observed and modeled in previous studies (Goff et al, ; Harter & Figlus, ; Sherwood et al, ; Wesselman et al, ), caused by higher water levels in the back‐barrier basin than on the ocean side, was also observed in this study, the total observed seaward sand transport is negligible since it adds up to ∼0.05 m 3 entirely. Research by Sherwood et al () and Harter and Figlus () found erosion and scour channels, driven by the seaward flow in the ebbing storm surge, which were not observed at our field location.…”

Section: Discussionsupporting

confidence: 91%

“…Large‐scale and local pressure gradients can oppose each other at times (Engelstad et al, ). Further, higher water levels in the back‐barrier basin than on the ocean side were observed to generate seaward flows (Engelstad et al, ; Hoekstra et al, ; Sherwood et al, ), which was also found in modeling studies (Harter & Figlus, ; Sherwood et al, ; Wesselman et al, ). In a combined observation‐modeling study of barrier island inundation in the Gulf of Mexico, Sherwood et al () found that the seaward directed water level gradient resulted in the deposition of a significant amount of sediment on the ocean side.…”

Section: Introductionmentioning

confidence: 72%

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Sand Suspension and Transport During Inundation of a Dutch Barrier Island

et al. 2018

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Overwash and inundation of barrier islands transport large amounts of sediment landward, which could potentially increase the aggradation of these islands in times of sea level rise. However, not much is known about the detailed processes of sediment suspension and transport during inundation. Here we analyze field data of suspended sediment, water levels, waves, and currents which were collected during five inundation events on a barrier island in the Netherlands. We found that depth‐integrated suspended sand concentrations and cross‐shore sand transport showed high variability during and between inundation events at our location, where 80% of the combined transport from all inundation events was completed before high tide. This is primarily caused by variations in cross‐shore flow velocities which were strongest (up to 1.2 m/s onshore) before high tide. However, episodically high depth‐integrated suspended sand concentrations (defined as >2kg/m2) were observed on infragravity time scales (∼20–200 s), suggesting that the contribution of infragravity waves to the combined bed shear stresses of waves and currents was important. High contributions of infragravity waves to the transport coincided with observed bore‐like wave shapes, which might partly be attributed to higher short waves riding and suspending sediment at the position of the crest. Two transport regimes were thus found to govern the transport during inundation: a flow‐driven regime when flow velocities were high (>0.5 m/s) and the ratio of infragravity wave and current related shields numbers was below 0.11 and an episodic regime when this ratio exceeded 0.11.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 72%

Sand Suspension and Transport During Inundation of a Dutch Barrier Island

et al. 2018

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“…The total transport during an inundation event is much smaller in the original simulations than in the simulations with equal water level in the North Sea and Wadden Sea, ranging from a decrease of 20% to 90% from class 1 to class 6. The important role of the back‐barrier basin when it is connected with the ocean or sea during inundation is also recognized in other studies, for example by Harter and Figlus (), Hoekstra et al. (), Sherwood et al.…”

Section: Discussionsupporting

confidence: 52%

“…The combination of wave‐ and wind‐induced set‐up and tidal variations, both in the North Sea and Wadden Sea, affects the magnitude and direction of the flow velocity across the island in the inundation regime (Engelstad et al. , ; Harter and Figlus, ; Hoekstra et al. , ; Sherwood et al.…”

Section: Introductionmentioning

confidence: 99%

The effect of tides and storms on the sediment transport across a Dutch barrier island

Wesselman

Winter

Engelstad

et al. 2017

Earth Surf Processes Landf

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Under natural conditions, barrier islands might grow vertically and migrate onshore under the influence of long‐term sea level rise. Sediment is transported onshore during storm‐induced overwash and inundation. However, on many Dutch Wadden Islands, dune openings are closed off by artificial sand‐drift dikes that prevent the influx of sediment during storms. It has been argued that creating openings in the dune row to allow regular flooding on barrier islands can have a positive effect on the sediment budget, but the dominant hydrodynamic processes and their influence on sediment transport during overwash and inundation are unknown. Here, we present an XBeach model study to investigate how sediment transport during overwash and inundation across the beach of a typical mesotidal Wadden Sea barrier island is influenced by wave, tide and storm surge conditions. Firstly, we validated the model XBeach with field data on waves and currents during island inundation. In general, the XBeach model performed well. Secondly, we studied the long‐term sediment transport across the barrier island. We distinguished six representative inundation classes, ranging from frequently occurring, low‐energy events to infrequent, high‐energy events, and simulated the hydrodynamics and sediment transport during these events. An analysis of the model simulations shows that larger storm events cause larger cross‐shore sediment transport, but the net sediment exchange during a storm levels off or even becomes smaller for the largest inundation classes because it is counteracted by larger mean water levels in the Wadden Sea that oppose or even reverse sediment transport during inundation. When taking into account the frequency of occurrence of storms we conclude that the cumulative effect of relatively mild storms on long‐term cross‐shore sediment transport is much larger than that of the large storm events. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

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“…Further, coupled hydrodynamic and morphodynamic models have been used in wave-dominated environments to simulate the observed subaerial response of relatively long straight beaches to hurricanes (Dissanayake et al, 2014;Harter & Figlus, 2017;Lindemer et al, 2010;Smallegan et al, 2016). Simulations of multiple storms on wave-dominated sandy beaches suggest that bathymetric change scales with wave energy and that storm direction can influence patterns of erosion and deposition (Luijendijk et al, 2017;Walstra et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Storm Impact on Morphological Evolution of a Sandy Inlet

2018

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Observations of waves, currents, and bathymetric change in shallow water (<10‐m depth) both inside and offshore of a migrating inlet with strong (2–3 m/s) tidal currents and complex nearshore bathymetry show over 2.5 m of erosion and accretion resulting from each of two hurricanes (offshore wave heights >8 m). A numerical model (Delft3D, 2DH mode) simulating waves, currents, and morphological change reproduces the observations with the inclusion of hurricane force winds and sediment transport parameters adjusted based on model‐data comparisons. For simulations of short hurricanes and longer nor'easters with identical offshore total time‐integrated wave energy, but different peak wave energies and storm durations, morphological change is correlated (R2 = 0.60) with storm intensity (total energy of the storm divided by the duration of the storm). Similarly, the erosion observed at the Sand Engine in the Netherlands is correlated with storm intensity. The observations and simulations suggest that the temporal distribution of energy in a storm event, as well as the total energy, impacts subsequent nearshore morphological change. Increased storm intensity enhances sediment transport in bathymetrically complex, mixed wave‐and‐tidal‐current energy environments, as well as at other wave‐dominated sandy beaches.

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Numerical modeling of the morphodynamic response of a low-lying barrier island beach and foredune system inundated during Hurricane Ike using XBeach and CSHORE

Cited by 72 publications

References 23 publications

Sand Suspension and Transport During Inundation of a Dutch Barrier Island

Sand Suspension and Transport During Inundation of a Dutch Barrier Island

The effect of tides and storms on the sediment transport across a Dutch barrier island

Storm Impact on Morphological Evolution of a Sandy Inlet

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