Experimental Study on the Performance of a Perched Beach Constructed With Geotextile Encapsulated-Sand Systems

Moreira, Andreia; Gomes, Jorge; Neves, Luciana das; Taveira-Pinto, Francisco; Lopes, Maria de Lurdes; Gomes, Fernando Veloso

doi:10.1142/9789814689977_0173

Cited by 1 publication

(1 citation statement)

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“…There are many factors that affect longevity of beach nourishments such as exposure to waves and in particular storm waves, their shape and other geometric parameters such as length [6,7], width and slope, and quality, density and grain size of fill material. Their stability is often enhanced by groynes, artificial headlands [8] and submerged sills [9,10]. As these beaches are built in environments where coastal erosion is dominant or local environmental conditions do not support the formation of natural beaches, they require regular maintenance and sediment replenishment.…”

Section: Introductionmentioning

confidence: 99%

Post-Nourishment Changes of an Artificial Gravel Pocket Beach Using UAV Imagery

Tadić

Ružić

Krvavica

et al. 2022

JMSE

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Monitoring and analysis of changes in the volume and area of nourished beaches is crucial to inform any beach renourishment programme. The aim of this study is to utilise UAV surveys and SfM photogrammetry to assess the beach nourishment performance of an artificial gravel beach exposed to a range of external forcing, including storms. The paper presents results from nineteen UAV surveys conducted between January 2020 and January 2021 at Ploče, an artificial beach in Rijeka (Croatia). The beach was nourished twice and eleven storm events, ranging from weak to strong, were recorded during this period. The Agisoft Metashape software was used to obtain point clouds and digital elevation models (DEM) from UAV images; Matlab and CloudCompare were used for further analysis of the DEMs. The accuracy and precision of the DEMs was assessed and uncertainty levels of ±5 cm were applied to all derived DEMs. The study provides new insights into the response of the emerged part of the beach to storms. Predictably, the largest changes were recorded after the first storm following beach nourishment. The longshore variability in the beach response to storms was identified from full 3D point clouds. Most of the lost sediment was from the east side of the beach, while the rest of the beach aligned with the predominant wave direction through cross-shore and longshore processes. Offshore/onshore sediment exchange between the lower and upper beach face on the western side manifested itself in beach profile steepening and berm formations. Overall, changes in beach volume and area were small, indicating that this artificial beach is relatively stable. The embayed layout following the natural coastal configuration appears to be effective in retaining nourished sediment on the beach. This work highlights the need to consider pocket embayed beaches in three dimensions, as traditional transect studies can overlook the three-dimensional behaviour. This study also highlighted the wider potential of UAVs and SfM for studies of high-resolution elevation changes on natural and artificial beaches, as well as for coastal monitoring of beach nourishment.

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