Effects of storm clustering on beach/dune evolution
Effects of storm clustering on beach/dune evolution
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DOI：
10.1016/j.margeo.2015.10.010
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发表时间：
2015-12
期刊：
影响因子：
2.9
通讯作者：
P. Dissanayake;Jennifer M. Brown;P. Wisse;H. Karunarathna
中科院分区：
文献类型：
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作者：
P. Dissanayake;Jennifer M. Brown;P. Wisse;H. Karunarathna
利用英国塞夫顿海岸Formby Point数值模式，研究了风暴集聚对海滩/沙丘地貌动力学的影响。所采用的风暴群是通过使用风暴阈值波高分析从2013年12月至2014年1月观测到的冬季风暴而建立的。这段时间发生的第一场风暴被认为是异常强烈的，发生这样一系列事件是非常不寻常的。建立了Formby Point高动力对岸的一维模型。在根据已有的风暴后廓线资料对模型参数进行初步校准后，将该模型用于风暴群的模拟。据推测，由于风暴之间的时间间隔很短，相邻风暴之间没有发生海滩恢复。因此，前一次风暴的最终预测的风暴后廓线被用作后续风暴的风暴前廓线。每一次风暴期间的预测演变都受到该星团中先前风暴的影响。由于集群效应，海床高度的变化与集群内事件的风暴功率不成正比，而在单个风暴情况下是成正比的。最初，大风暴事件与多层前滨相互作用，使随后的较弱风暴影响上海滩和下沙丘系统。这导致沙丘脚趾水平的变化更大，在随后不那么严重的风暴期间也是如此。研究还表明，在极端风暴条件下，通常用于确定沙丘侵蚀的水位阈值比预测的高出约1米。预报的剖面演变对风暴群期间海滩/沙丘系统的地貌动力学过程(以Formby Point为例)提供了有用的见解，这对于量化风暴群的群聚效应，开发海岸管理工具非常有用。
Impacts of storm clustering on beach/dune morphodynamics were investigated by applying the state-of-the-art numerical model XBeach to Formby Point (Sefton coast, UK). The adopted storm cluster was established by analysing the observed winter storms from December 2013 to January 2014 using a storm threshold wave height. The first storm that occurred during this period is regarded as exceptionally intense, and the occurrence of such a cluster of events is very unusual. A 1D model was setup for the highly dynamic cross-shore at Formby Point. After initial calibration of the model parameters against available post-storm profile data, the model was used for the simulation of the storm cluster. It was assumed that no beach recovery occurred between adjacent storms due to the very short time intervals between storms. As a result, the final predicted post-storm profile of the previous storm was used as the pre-storm profile of the subsequent storm. The predicted evolution during each storm was influenced by the previous storms in the cluster. Due to the clustering effect, the bed level change is not proportional to the storm power of events within the cluster, as it would be in an individual storm case. Initially, the large storm events interact with the multi-bared foreshore enabling the subsequent weaker storms to influence the upper beach and lower dune system. This results in greater change at the dune toe level also during less severe subsequent storms. It is also shown that the usual water level threshold used to define dune erosion is over predicted by about 1 m for extreme storm conditions. The predicted profile evolution provides useful insights into the morphodynamic processes of beach/dune systems during a storm cluster (using Formby Point as an example), which is very useful for quantifying the clustering effects to develop tools for coastal management.