Computational modelling of morphodynamic response of a macro-tidal beach to future climate variabilities
Computational modelling of morphodynamic response of a macro-tidal beach to future climate variabilities
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DOI：
10.1016/j.margeo.2019.105960
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发表时间：
2019-09
期刊：
影响因子：
2.9
通讯作者：
W. G. Bennett;H. Karunarathna;D. Reeve;N. Mori
中科院分区：
文献类型：
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作者：
W. G. Bennett;H. Karunarathna;D. Reeve;N. Mori
全球气候变化有可能影响世界各地的许多海岸线，并可能对海岸线的稳定性及其作为天然海岸防御工事的功能产生不利影响。本文研究了未来极端风暴和海平面上升对英国塞夫顿海岸大潮地貌动力学的影响，以基于过程的模式为工具模拟风暴期间未来海滩变化的快照。塞夫顿海岸是英国最大的沙丘系统之一，在那里，正面沙丘起到了抵御极端条件的天然屏障的作用。未来的风暴条件是根据21世纪末全球对未来海浪的预测而确定的。未来的海平面是根据英国环境局(EA)设定的气候变化容限来确定的，而未来的涌浪条件则是根据EA提供的指导方针来确定的。该模型套件首先根据测量的海浪、水位和海滩变化进行了验证，然后使用它模拟了许多具有统计意义的未来风暴条件下的地形动态变化。然后将未来风暴引起的塞夫顿海岸地貌动力变化与目前风暴引起的地形动力变化进行了比较。结果表明，该海滩将经历显着的气候变化驱动的影响，沙丘在风暴期间的后退将在未来相当高。结果还表明，由于海滩的形状和其朝向主要的波浪接近方向，对风暴的地形动力响应将有很强的沿岸变异性。研究还发现，沙丘前的水位(以及由此产生的潮汐和未来的海平面上升)是决定风暴期间海滩侵蚀的最关键因素。
Global climate variabilities have the potential to impact many coastlines around the world, and can have detrimental effects on the stability of coastlines and their function as natural coastal defenses. This paper investigates the impacts of future extreme storms and sea level rise on morphodynamics of the macro-tidal Sefton Coast, UK, taking a process-based model as a tool to simulate a snap-shot of future beach change during storms. Sefton Coast represents one of the largest dune systems in the UK, where frontal dunes function as a natural barrier against extreme conditions. Future storm conditions were determined from global predictions of future waves at the end of the twenty first century. Future sea levels were determined based on climate change allowances set by the UK Environment Agency (EA), while future surge conditions were determined based on the guidelines also provided by EA.A nested numerical modelling approach, that combined a regional scale model with a local scale model with high resolution, is used. The modelling suite was first validated against measured waves, water levels and beach change, before using it to simulate morphodynamic change from numerous statistically significant ‘future’ storm conditions. Future storm-induced morphodynamic change of the Sefton coast was then compared with that from the present storms. The results reveal that this beach will experience significant climate change driven impacts where dune retreat during storms will be considerably higher in future. The results also reveal that due to the shape of the beach and its orientation to predominant wave approach direction, there will be a strong longshore variability of morphodynamic response to storms. It was also found that the water level in front of the dune (and hence surge and future sea level rise) is the most critical factor that determines beach erosion during a storm.