State of Knowledge on Measurement and Modeling of Coastal Overwash

Donnelly, Chantal; Kraus, Nicholas C.; Larson, Magnus

doi:10.2112/04-0431.1

Cited by 224 publications

(203 citation statements)

References 37 publications

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“…For extreme conditions, when storm surge elevations exceed the berm crest, wave overtopping may combine with a steady flood flow (Hughes & Nadal 2009), and berm rollover and breaching of the barrier may occur. Overviews of these processes are given by Kraus et al (2002) and Donnelly et al (2006). Similar processes may occur owing to tsunami overtopping and subsequent drawdown.…”

Section: Background (A) Previous Studiesmentioning

confidence: 99%

Overtopping of solitary waves and solitary bores on a plane beach

2012

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The overtopping of solitary waves and bores present major hazards during the initial phase of tsunami inundation and storm surges. This paper presents new laboratory data on overtopping events by both solitary waves and solitary bores. Existing empirical overtopping scaling laws are found to be deficient for these wave forms. Two distinct scaling regimes are instead identified. For solitary waves, the overtopping rates scale linearly with the deficit in run-up freeboard. The volume flux in the incident solitary wave is also an important parameter, and a weak dependence on the nonlinearity of the waves (H /d) is observed. For solitary bores, the overtopping cannot be scaled uniquely, because the fluid momentum behind the incident bore front is independent of the bore height, but it is in close agreement with recent solutions of the nonlinear shallow water equations. The maximum overtopping rate for the solitary waves is shown to be the lower bound of the overtopping rate for the solitary bores with the same deficit in freeboard. Thus, for a given run-up, the solitary bores induce greater overtopping rates than the solitary waves when the relative freeboard is small.

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Section: Background (A) Previous Studiesmentioning

confidence: 99%

Overtopping of solitary waves and solitary bores on a plane beach

2012

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“…Washover refers to the deposit of sediment landward of the beach caused by overwash (Schwartz, 1975). There are two endmember causes of overwash: run-up overwash and inundation overwash (Donnelly et al, 2006). Run-up overwash occurs when wave run-up causes the barrier to be overtopped and the resulting washovers are typically small and generally fan-shaped (the overwash regime of the Sallenger (2000) impact scale; figure 1; Donnelly et al, …”

Section: Overwash Processes and Depositsmentioning

confidence: 99%

“…On undeveloped coasts, overwash typically dominates, causing barriers to "roll over" (Dillon, 1970;Byrnes and Gingerich, 1987;Dolan and Godfrey, 1973;Schwartz, 1975). Here, it results from a combination of hurricanes and winter northeast storms (Donnelly et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Quantifying overwash flux in barrier systems: An example from Martha's Vineyard, Massachusetts, USA

et al. 2013

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Coastal barriers are particularly susceptible to the predicted effects of accelerated of sea-level rise and the potential for increased impacts of intense storms. Over centennial scales, barriers are maintained via overtopping during storms, causing deposition of washover fans on their landward sides. This study examines three washover fans on the south shore of Martha's Vineyard using a suite of data including vibracores, ground penetrating radar, high resolution dGPS, and LiDAR data. From these data, the volumes of the deposits were determined and range from 2.1-2.4 x 10 4 M .Two overwashes occurred during Hurricane Bob in 1991. The water levels produced by this storm have a return interval of ~28 years, resulting in an onshore sediment flux of 2.4-3.4 m 3 /m/yr. The third washover was deposited by a nor'easter in January 1997, which has a water level return interval of ~6 years, resulting in a flux of 8.5 m 3 /m/yr. These fluxes are smaller than the flux of sediment needed to maintain a geometrically stable barrier estimated from shoreline retreat rates, suggesting that the barrier is not in long-term equilibrium, a result supported by the thinning of the barrier over this time interval.

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“…dune or barrier island) that does not directly return to the ocean from where it originated. 1 Only a few formulas have been developed to estimate sediment transport by overwash and they are typically based on the flow of water over the crest. 7,19,20 In more sophisticated formulations different approaches are employed depending on the type of overwash regime -that is, whether run-up or inundation overwash occurs.…”

Section: Transport In Overwashmentioning

confidence: 99%

“…Overwash occurs if the wave run-up and/or the mean water level are sufficiently high allowing for water and sediment to pass the beach crest, which in turn causes flooding and deposition of sediment shoreward of the crest. 1 In the case of overwash, severe lowering of the crest may take place, increasing the probability of flooding and breaching as the natural defence offered by subaerial morphological formations (e.g. dunes) is weakened.…”

mentioning

confidence: 99%

Analytical model of beach erosion and overwash during storms

Larson

Donnelly

Jiménez

et al. 2009

Proceedings of the Institution of Civil Engineers - Maritime En

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During severe storms high waves and water levels may greatly impact the sub-aerial portion of the beach inducing significant morphological change at elevations that the waves can not reach under normal conditions. Morphological formations such as dunes and barrier islands may suffer from direct wave impact and erode. Overwash occurs if the wave run-up and/or the mean water level are sufficiently high allowing for water and sediment to pass over the beach crest, which in turn causes flooding and deposition of sediment shoreward of the crest. An analytical model of sub-aerial beach response to storms was developed based on impact theory, including overwash, and the evolution of schematised dunes was investigated. Furthermore, the analytical model was applied to the case of schematised barrier islands exposed to extensive overwash. After validation using field data, the analytical model was employed at two coastal sites, namely Ocean City on the United States east coast and the Ebro Delta on the Spanish Mediterranean coast, in order to calculate quantities for assessing the storm impact on beaches, such as eroded volume, overwash volume, beach crest reduction, and contour-line retreat. These quantities were subsequently analysed to derive empirical probability distribution functions to be utilised in different types of risk assessment concerning flooding and erosion in coastal areas. NOTATION

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State of Knowledge on Measurement and Modeling of Coastal Overwash

Cited by 224 publications

References 37 publications

Overtopping of solitary waves and solitary bores on a plane beach

Overtopping of solitary waves and solitary bores on a plane beach

Quantifying overwash flux in barrier systems: An example from Martha's Vineyard, Massachusetts, USA

Analytical model of beach erosion and overwash during storms

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