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Immediate pre-storm bathymetry is a key input required for numerical models used in coastal hazard Early Warning Systems. However, the expense and challenging nature of hydrographic surveying means that the availability of high-quality data is extremely rare. This study evaluates the extent to which synthetic and representative bathymetry alternatives can be used to obtain reliable predictions of storm induced sub-aerial erosion using the XBeach coastal erosion numerical model. Multiple storm events at 2 contrasting sites are modelled using 6 bathymetry scenarios including pre-storm surveyed bathymetries, an average bathymetry, and Dean profiles. The output is analysed to evaluate the skill of XBeach erosion predictions as a function of the bathymetry used.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/bE3aXVXxZqQ

When beach changes occur owing to the imbalance of longshore sand transport, not only bathymetric changes but also grain size changes occur, having an impact on the coastal environment. With the increase in the anthropogenic impact, such changes have been observed on many coasts. Here, the bathymetric changes and changes in grain size of seabed materials were investigated on the basis of a numerical simulation using the BG model (a three-dimensional model for predicting beach changes based on Bagnold’s concept), with northern Kujukuri Beach in Japan as the study area.

This study is an analysis about morphological problems, due to anthropic or other causes. We carried out the behavior and evolution of ten beaches on the North Coast of Spain, in order to see if climate change was involved. To do this, it was necessary to consider data from Cantabrian sea buoys during fifteen years. Besides we made use of, maps, nautical charts and bathymetric records. We applied a kind of parameters to measure the energy including on each beach, so to be able to compare therm.

In this work, a data assimilation approach treating bathymetry as an uncertain model parameter, is introduced where direct dissipation estimates from remote sensing data are the unique data source. Two dimensional wave breaking dissipation fields are retrieved on a wave-by-wave basis with the algorithms of Daz et al. (2018), who were able to reliably estimate breaking dissipation by removing spurious signals affecting electro-optical and microwave data. After a six hour application, the system was able to retrieve improved bathymetric estimates, without any in situ depth measurement. A prominent feature of this approach is its ability to reliably capture the amplitude and position of nearshore sandbars.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/Y7mgiSvmRYc

Extreme storms can cause rapid morphological changes that pose high risk to society (Sallenger 2000). Semiempirical and process-based models often are used to simulate storm-induced coastal processes (Roelvink et al. 2009, Palmsten & Holman 2012, Stockdon et al. 2014, Overbeck et al. 2017). However, there are few observations of surfzone waves and currents during extreme storms. Therefore, parameterizations often are calibrated by minimizing model-data errors for pre- to post-storm bathymetric and topographic changes, and the accuracy of the simulated processes during the storm is unknown. Here, surf, swash, and dune observations collected near Duck, NC, USA, will be used to investigate wave processes and dune erosion during the passage of recent (2015-2017) Hurricanes.

This contribution analyses the hydro-morphological effects induced by low crested structures confined by lateral groynes at Igea Marina beach, Northern Adriatic Sea, Italy. The site has been monitored since the works started for these last ten years. Results from bathymetric surveys, sediment samplings, video monitoring and numerical modelling are presented and discussed.

In this study, the possibility to get sedimentological (density, compaction) and hydrodynamical (suspended sediment concentration, turbulence) information from ALB surveys is demonstrated. ALB laser reflectance was found to be higher on the lee-side and on the crest of the ripple bedform than in the trough and on the stoss-side. Moreover, laser reflectance was also found to be higher on "active† subtidal dunes, located within the depth of action of the waves, than on deeper "passive† bedforms. Based on lab experiments conducted in a hydraulic flume under X-ray CT-Scanner, these observations were related to sediment compaction and suspended sediment.

The elongation of a sand spit on a seabed with different water depths and slopes was numerically simulated using the BG model (a three-dimensional model for predicting beach changes based on Bagnold’s concept). The examples of sand spits and a pond enclosed by a barrier were examined first using aerial photographs and bathymetric survey maps. The formation of a sand spit and a barrier was predicted using the BG model under the conditions that the water depths where a sand spit is formed were changed to 5, 10, 15, and 20 cm in a model scale of 1/100, and that the seabed slopes were changed to 1/50, 1/40, 1/30, and 1/20. The difference in the form of a sand spit and a barrier formed under these conditions was explained and compared with the natural sand spits and a barrier.

Cross-shore beach profile data from field measurements performed at six locations on the southern coast of the Caspian Sea are used to investigate bathymetry change due to various wave conditions. Beach profile measurements are analyzed and subsequently compared with the results of a berm formation and erosion model. The model comprises distinct empirical sediment transport equations for predicting the cross-shore sediment transport rate under various wave conditions. To yield a berm formation and erosion model, empirical cross-shore sediment transport equations are combined with the mass conservation equation. Simulations results obtained from the model compared well with the measurements, proving the capability of the model in simulating berm formation and erosion evolution.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/FTgAr73h5rA