scholarly journals Hotspot dune erosion on an intermediate beach

2021 ◽  
pp. 103998
Author(s):  
Nicholas Cohn ◽  
Katherine Brodie ◽  
Bradley Johnson ◽  
Margaret Palmsten
Keyword(s):  
Dune Erosion

Unpacking storm damages on a developed shoreline: Relating dune erosion and urban runoff

Shore & Beach ◽  
2019 ◽  
pp. 35-45
Author(s):  
Patrick Barrineau ◽  
Timothy Kana
Keyword(s):  
South Carolina ◽  
Storm Events ◽  
Near Surface ◽  
Dune Erosion ◽  
Groundwater Flux ◽  
Impact Scale ◽  
Cape Hatteras ◽  
Myrtle Beach ◽  
Rain Events ◽  
Elevation Model

Hurricane Matthew (2016) caused significant beach and dune erosion from Cape Hatteras, North Carolina, USA, to Cape Canaveral, Florida, USA. At Myrtle Beach, South Carolina, the storm caused beach recession, and much of the southern half of the city’s beaches appeared to be overwashed in post-storm surveys. Around half of the city’s beaches appeared overwashed following the storm; however, the Storm Impact Scale (SIS; Sallenger 2000) applied to a pre-storm elevation model suggests less than 10% of the city’s beaches should have experienced overwash. Spatial analysis of elevation and land cover data reveals dunes that were “overwashed” during Matthew drain from watersheds that are >35% impervious, where those showing only dune recession are <5% impervious. The densely developed downtown of Myrtle Beach sits on a low seaward-sloping terrace. Additionally, indurated strata beneath the downtown area can prevent groundwater from draining during excessive rain events. As a result, the most continuous impervious surface cover and near-surface strata lie within a half-kilometer of the beach and drain directly to the backshore. Along the U.S. Southeast coast, this is somewhat rare; many coastal systems feature a lagoon or low-lying bottomland along their landward border, which facilitates drainage of upland impervious surfaces following storm passage. At Myrtle Beach, all of the stormwater runoff is drained directly to the beach through a series of outfall pipes. Many of the outfall pipes are located along the backshore, near the elevation of storm surge during Matthew. Runoff from Matthew’s heavy rains was observed causing ponding on the landward side of the foredune and scouring around beach access walkways. Based on these observations, the severe dune erosion experienced near downtown Myrtle Beach during Hurricane Matthew may have been caused by runoff and/or groundwater flux rather than overwash. These results highlight an unexpected relationship between upland conditions and dune erosion on a developed shoreline. That is, dune erosion can be caused by mechanisms beside overwash during storm events.

scholarly journals Process-Based Model Prediction of Coastal Dune Erosion through Parametric Calibration

2021 ◽  
Vol 9 (6) ◽  
pp. 635
Author(s):  
Hyeok Jin ◽  
Kideok Do ◽  
Sungwon Shin ◽  
Daniel Cox
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Model Performance ◽  
Coastal Dunes ◽  
Wave Transformation ◽  
Storm Event ◽  
Face Model ◽  
Dune Erosion ◽  
Simulation Performance ◽  
Sand Bar

Coastal dunes are important morphological features for both ecosystems and coastal hazard mitigation. Because understanding and predicting dune erosion phenomena is very important, various numerical models have been developed to improve the accuracy. In the present study, a process-based model (XBeachX) was tested and calibrated to improve the accuracy of the simulation of dune erosion from a storm event by adjusting the coefficients in the model and comparing it with the large-scale experimental data. The breaker slope coefficient was calibrated to predict cross-shore wave transformation more accurately. To improve the prediction of the dune erosion profile, the coefficients related to skewness and asymmetry were adjusted. Moreover, the bermslope coefficient was calibrated to improve the simulation performance of the bermslope near the dune face. Model performance was assessed based on the model-data comparisons. The calibrated XBeachX successfully predicted wave transformation and dune erosion phenomena. In addition, the results obtained from other two similar experiments on dune erosion with the same calibrated set matched well with the observed wave and profile data. However, the prediction of underwater sand bar evolution remains a challenge.

scholarly journals DUNE EROSION AND SEDIMENT PROFILE DUE TO WAVE UPRUSH

1988 ◽  
Vol 1 (21) ◽  
pp. 106
Author(s):  
T.A. Fenaish ◽  
M.F. Overton ◽  
J.S. Fisher
Keyword(s):  
Steady State ◽  
Shoreline Change ◽  
Meteorological Conditions ◽  
Beach Profile ◽  
Coastal Regions ◽  
Steady State Condition ◽  
Severe Storms ◽  
Dune Erosion ◽  
Major Threat ◽  
Equilibrium Profile

Shorelines are continuously adjusting in response to the changing hydraulic and meteorological conditions. Storms that generate large waves and surge conditions can alter the nearshore topography and relocate the beach shorelines, often with substantial amounts of beach and dune erosion. Such storms pose a major threat to coastal developments for which the economic impact can be significant. The ability to predict the rate of erosion and, consequently the shoreline change, is important in making decisions regarding the planning and managing of the coastal regions. In general, the available methods for the prediction of beach and dune erosion are based on the assumption of post-storm equilibrium profile. In this approach it is assumed that, for a given set of wave and surge conditions, the entire beach reaches a steadystate, and that the volume of sand released from the dune is equal to the volume of sand required to establish this profile. Existing methods that are based on this concept include those developed by Edelman (1968, 1972), Vellinga (1982, 1983, 1986), Kriebel and Dean (1984), Sargent and Birkemeier (1985), and Kobayashi (1987).. The reliance of these methods on the assumption of steady-state condition limits their application to extreme events generated by severe storms. Generally, storms do not have sufficient duration or intensity, such that the beach profile attains equilibrium during the storm.

scholarly journals MODELLING DUNE EROSION OF THE SEFTON COAST, LIVERPOOL BAY, UK

2014 ◽  
Vol 1 (34) ◽  
pp. 4
Author(s):  
Pushpa Dissanayake ◽  
Harshinie Karunarathna
Keyword(s):  
Liverpool Bay ◽  
Dune Erosion

scholarly journals Below-ground biomass of plants, with a key contribution of buried shoots, increases foredune resistance to wave swash

2019 ◽  
Author(s):  
Davide De Battisti ◽  
John N Griffin
Keyword(s):  
Erosion Resistance ◽  
Coastal Protection ◽  
Flume Experiments ◽  
Plant Component ◽  
Dune Erosion ◽  
Perennial Plants ◽  
Ground Biomass ◽  
Cakile Maritima ◽  
Below Ground ◽  
The Impact

Abstract Background and aims Sand dunes reduce the impact of storms on shorelines and human infrastructure. The ability of these ecosystems to provide sustained coastal protection under persistent wave attack depends on their resistance to erosion. Although flume experiments show that roots of perennial plants contribute to foredune stabilization, the role of other plant organs, and of annual species, remains poorly studied. Furthermore, it remains unknown if restored foredunes provide the same level of erosion resistance as natural foredunes. We investigated the capacity of three widespread pioneer foredune species (the perennial Ammophila arenaria and the annuals Cakile maritima and Salsola kali) to resist dune erosion, and compared the erosion resistance of Ammophila at natural and restored sites. Methods Cores collected in the field were tested in a flume that simulated a wave swash. A multi-model inference approach was used to disentangle the contributions of different below-ground compartments (i.e. roots, rhizomes, buried shoots) to erosion resistance. Key Results All three species reduced erosion, with Ammophila having the strongest effect (36 % erosion reduction versus unvegetated cores). Total below-ground biomass (roots, rhizomes and shoots), rather than any single compartment, most parsimoniously explained erosion resistance. Further analysis revealed that buried shoots had the clearest individual contribution. Despite similar levels of total below-ground biomass, coarser sediment reduced erosion resistance of Ammophila cores from the restored site relative to the natural site. Conclusions The total below-ground biomass of both annual and perennial plants, including roots, rhizomes and buried shoots, reduced dune erosion under a swash regime. Notably, we show that (1) annual pioneer species offer erosion protection, (2) buried shoots are an important plant component in driving sediment stabilization, and (3) management must consider both biological (plants and their traits) and physical (grain size) factors when integrating dunes into schemes for coastal protection.

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