Effect of beach slope and grain-stabilization on coastal sediment transport: An attempt to overcome the erosion overestimation by XBeach

Elsayed, Saber M.; Oumeraci, Hocine

doi:10.1016/j.coastaleng.2016.12.009

Cited by 49 publications

(41 citation statements)

References 53 publications

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“…This means that the prediction capability of XBeach might substantially decrease with higher overtopping rates, which is in full agreement with the overestimation of erosion associated COASTAL ENGINEERING 2018 6 with higher flow velocity regimes as often reported in the literature (e.g. Bisschop et al, 2016Bisschop et al, , 2010De Vet, 2014;Elsayed and Oumeraci, 2017c;McCall et al, 2010). As shown in Fig (4.c), this overestimation by XBeach is verified by comparing the observed and the modelled crest recession for all the 17 GWKtests.…”

Section: Assessment Of Xbeach Performance By Means Of Large-scale Dunsupporting

confidence: 86%

“…Furthermore, XBeach has sufficiently proved his capability to predict overtopping rates as compared to empirical equations and/or neural network tool recommended by static models (e.g. EurOtop of Van der Meer et al 2016), which are also unsuitable to calculate the inland discharge through a breach-induced inlet because of the dynamic nature of the breaching process (Elsayed and Oumeraci, 2017c). In addition, XBeach is capable to generate long and short-crested waves at the offshore boundary (Elsayed andOumeraci, 2016a, 2016b).…”

Section: The Xbeach-seawat Model Systemmentioning

confidence: 99%

“…The results showed a very good prediction capability of the improved model. Meanwhile, since their publication in (Elsayed and Oumeraci, 2017c), these model improvements have been applied in several research studies (e.g. Park et al, 2018) to improve the prediction capability of XBeach.…”

Section: Improvement Of Modelling Of Sediment Stirring In Xbeachmentioning

confidence: 99%

“…Therefore, a large part of the erosion overestimation by XBeach is assumed to be attributed to the underestimation of the critical Shields parameter for incipient sediment motion. Elsayed and Oumeraci (2017c) have demonstrated that there are unaccounted forces in the formulation of the critical Shields parameter such as (i) the uprooting force to overcome the sediment interlocking, especially for consolidated/compacted soils and (ii) biological and/or chemical (salty) stabilizations. Thus, the overestimation of the erosion rates by XBeach can partially be attributed to the omission of such grain-stabilizing effects on critical bed shear stresses for incipient sediment motion.…”

Section: (B) Grain-stabilization Effect On the Inception Of Sediment mentioning

confidence: 99%

“…The performance of the improved XBeach model was examined for three selected test cases (see Elsayed and Oumeraci, 2017c). The selection of these cases was mainly based on the need to separately test the effect of the proposed improvements on (i) frontal dune erosion (the large-scale GWK-tests mentioned above are used for this purpose), (ii) sand barrier breaching and (iii) erosion and overwash of a barrier island under an extreme storm surge.…”

Section: (C) Validation Of Model Modificationsmentioning

confidence: 99%

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Erosion and Breaching of Coastal Barriers in a Changing Climate: Associated Processes and Implication for Contamination of Coastal Aquifers

Elsayed¹,

Oumeraci²,

Goseberg³

2018

Int. Conf. Coastal. Eng.

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Europe and many other countries all over the world are often surrounded by coastal defence systems (e.g. protective dunes and dykes) in order to protect coastal areas from threats of wave attack, storm surges and subsequent coastal floods. During moderate sea conditions, wave attack and coastal erosion is limited to nearshore areas and may only cause shore erosion. Under the same conditions, fresh groundwater, which is hydraulically interconnected with seawater, is in equilibrium with the laterally intruding seawaters. Such equilibrium prevails as long as the moderate sea level (MSL) and the hydrogeological conditions at the sea/land boundary are stationary. However, during extreme storm surges, the higher water levels may temporally threaten the coastal defence systems. In fact, shortwaves riding on the temporally rising sea level during storm surge events may directly runup, rundown and/or impact on barriers, possibly causing seaward erosion followed by lowering of barrierâ€™s crest and hence wave overtopping or overflow through combined surge and waves. As a result, barriers may breach, inducing coastal inundation and subsequent vertical saltwater intrusion (VSWI) behind the breached barriers due to the vertical infiltration of inundating seawater into the fresh groundwater. In this study, a new integral physically based methodology is developed to reliably assess the possible implications of extreme storm surges on the safety of coastal barriers and the implications of possible breaching for contamination of coastal aquifers. The integral model is therefore capable to successively simulate breaching/overtopping of coastal barriers forced by storm surges as a hydraulic load, induced flood propagation in the hinterland and subsequent VSWI into coastal aquifers while considering the complexity of these processes and mutual interaction among them. The modelling methodology consists of an improved XBeach code (Roelvink et al., 2009) for hydro-morphodynamics unidirectionally coupled with the SEAWAT code (Langevin et al., 2008) for groundwater flow. The model is applied to a case study in northern Germany, showing that marine floods represent a serious threat to usability of coastal aquifers which are extremely important water resources. Outcomes of model application showed that a coastal flood event of a few hours may contaminate coastal aquifers for many decades, thus reducing the agricultural yield and hindering the sustainable development in coastal areas prone to coastal floods. This study represents, to the knowledge of the author, the first systematic research study that addresses the safety of natural coastal sandy barriers under extreme storm surge conditions together with the consequences of possible barrier breaching and overwash on subsequent flooding and saltwater intrusion into fresh groundwater. Moreover, it is probably the foremost study that attempts to mitigate storm-driven saltwater intrusion through the use and modelling of a subsurface drainage network. Besides improving the agricultural yield in coastal areas, the use of subsurface drainage network significantly reduces the natural remediation interval required for aquifers recovery after a coastal flood event. Moreover, it limits the vertical extent of the salt intrusion. The multiple flow domains and aspects discussed in this research make it a multi-disciplinary study that is quite relevant for the coastal engineering community, for flood risk managers, for coastal hydrologists, for groundwater suppliers as well as for sustainable development planners.

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Section: Assessment Of Xbeach Performance By Means Of Large-scale Dunsupporting

confidence: 86%

Section: The Xbeach-seawat Model Systemmentioning

confidence: 99%

Section: Improvement Of Modelling Of Sediment Stirring In Xbeachmentioning

confidence: 99%

Section: (B) Grain-stabilization Effect On the Inception Of Sediment mentioning

confidence: 99%

Section: (C) Validation Of Model Modificationsmentioning

confidence: 99%

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Erosion and Breaching of Coastal Barriers in a Changing Climate: Associated Processes and Implication for Contamination of Coastal Aquifers

Elsayed¹,

Oumeraci²,

Goseberg³

2018

Int. Conf. Coastal. Eng.

Self Cite

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Observation of the Coastal Areas, Estuaries and Deltas from Space

et al. 2023

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Coastal regions (including estuaries and deltas) are very complex environments with diverse hydrodynamic and bio-geomorphological contexts and with important socio-economic and ecological problems. These systems are among the most affected by human impact through urbanization and port activities, industrial and tourism activities. They are directly affected by the impact of climate change on sea level, storm surges frequency and strength, as well as recurrence of coastal river floods. A sustainable future for coastal zones depends on our capacity to implement systematic monitoring with focus on: (1) forcings affecting coastal zones at different spatio-temporal scales (sea level rise, winds and waves, offshore and coastal currents, tides, storm surges, river runoff in estuaries and deltas, sediment supply and transport, vertical land motions and land use); (2) morphological response (e.g., shoreline migration, topographical changes). Over the last decades, remote sensing observations have contributed to major advances in our understanding of coastal dynamics. This paper provides an overview of these major advances to measure the main physical parameters for monitoring the coastal, estuarine and delta environments and their evolution, such as the water level and hydrodynamics near the shoreline, water/sediment contact (i.e., shoreline), shoreline position, topography, bathymetry, vertical land motion, bio-physical characteristics of sediments, water content, suspended sediment, vegetation, and land use and land cover.

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An investigation of the morphodynamic change of reef islands under monochromatic waves

Yao,

Zhou,

Zhao

et al. 2023

Acta Oceanol. Sin.

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Effect of beach slope and grain-stabilization on coastal sediment transport: An attempt to overcome the erosion overestimation by XBeach

Cited by 49 publications

References 53 publications

Erosion and Breaching of Coastal Barriers in a Changing Climate: Associated Processes and Implication for Contamination of Coastal Aquifers

Erosion and Breaching of Coastal Barriers in a Changing Climate: Associated Processes and Implication for Contamination of Coastal Aquifers

Observation of the Coastal Areas, Estuaries and Deltas from Space

An investigation of the morphodynamic change of reef islands under monochromatic waves

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