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Effect of beach slope and grain-stabilization on coastal sediment transport: An attempt to overcome the erosion overestimation by XBeach
- Source :
- Coastal Engineering. 121:179-196
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- The reproduction of seventeen laboratory tests for dune erosion by the surf-beat mode of the two-dimensional horizontal (2DH) model XBeach for storm wave conditions showed that the model overestimates the erosion and thus the deposition volumes. This overestimation becomes particularly significant for very large overtopping rates on coastal barriers, which are commonly induced by extreme storm surges. In this paper, the recent model improvements to overcome this problem are first summarised. Moreover, two physical reasons for these overestimations are identified: (i) the wave nonlinearity effect on sediment transport, which is described in XBeach by a calibration factor for the time-averaged flow depending on the wave skewness and asymmetry and (ii) the considerable excess of the actual shear stress required to initiate the sediment particle motion as compared to that predicted by the common Shields curve. To improve the prediction capability of XBeach in terms of erosion and overwash volumes, two new improvements, related to the two aforementioned reasons for the overestimation, are introduced and implemented in the model. The improved XBeach model is then tested for dune erosion, for barrier breaching as well as for a barrier island erosion and overwash under an extreme storm surge event. The results showed a very good prediction capability of the improved model. Particularly, the second model improvement opens the way toward further model improvements to account for spatially varying soil resistance, which is crucial for reliable prediction of a barrier breaching.
- Subjects :
- Environmental Engineering
010504 meteorology & atmospheric sciences
0208 environmental biotechnology
Flow (psychology)
Storm surge
Ocean Engineering
02 engineering and technology
01 natural sciences
Deposition (geology)
020801 environmental engineering
Barrier island
Erosion
Shear stress
Environmental science
Geotechnical engineering
Overwash
Sediment transport
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 03783839
- Volume :
- 121
- Database :
- OpenAIRE
- Journal :
- Coastal Engineering
- Accession number :
- edsair.doi...........a757cfb1ebe926c519aea6c758d46f97