Coastal and Marine Research Centre, Griffith University, Gold Coast campus, G51, QLD 4222, Australia; School of Engineering and Built Environment, Griffith University, Gold Coast campus, Australia.
Coastal and Marine Research Centre, Griffith University, Gold Coast campus, G51, QLD 4222, Australia.
Sci Total Environ. 2021 Nov 1;793:148591. doi: 10.1016/j.scitotenv.2021.148591. Epub 2021 Jun 24.
In this paper, a natural headland bypassing is investigated in terms of its short (months to years) and long-term (years to decades) variability and its relationship with wave conditions, climate drivers and anthropogenic interventions. The research is focused on Fingal Head (New South Wales, Australia) where nine detailed topo-bathymetric surveys were undertaken between June 2018 and January 2020. To extend the analysis in time, over 30 years of satellite and aerial images were used to describe the headland bypassing variability based on the shoreline and sandbar position changes. Shoreline and sandbar positions presented moderate to strong correlation between updrift and immediate downdrift of the headland highlighting the influence of the bypassing process for the longshore transport on the study area. Results indicate that the headland bypassing around Fingal Head is governed by two distinct processes and their dominance is controlled by waves and sediment availability. The sandbar-driven bypassing scenario requires a storm wave event to trigger the sandbar system and over seven months to complete the full bypassing cycle. A quicker bypassing cycle (i.e. few months) happens when sediment leaks around the headland following a persistent low energy wave condition that largely accretes the updrift upper beach. Headland bypassing cycles occur in multiple timescales, including seasonal variability of the wave climate to interannual and decadal cycles of shoreline progradation and retreat. Shifts in the large-scale climate drivers such as El Niño-Southern Oscillation, Pacific Decadal Oscillation and Interdecadal Pacific Oscillation were observed to influence on changes to the low frequency of variability of the headland bypassing in the study area by affecting the predominant wave direction and updrift beach sand availability. The understanding of this intermittent nature of the headland bypassing process and particularly considering its periodicity and the related driving forces is crucial to predict future coastal hazards and develop management strategies.
本文从短期（数月至数年）和长期（数年至数十年）变化的角度研究了天然岬角绕流及其与波浪条件、气候驱动因素和人为干预的关系。研究集中在新南威尔士州芬格尔头（Fingal Head），2018 年 6 月至 2020 年 1 月期间进行了九次详细的地形-水深测量调查。为了在时间上扩展分析，利用 30 多年的卫星和航空图像来描述岬角绕流的变化，基于海岸线和沙坝位置的变化。岬角上下游的海岸线和沙坝位置之间呈现出中等至强相关，突出了绕流过程对研究区沿岸输沙的影响。结果表明，芬格尔头周围的岬角绕流受两个不同过程的控制，其主导地位受波浪和泥沙供应的控制。沙坝驱动的绕流情景需要风暴波事件触发沙坝系统，并需要七个月的时间才能完成整个绕流周期。当持续的低能量波浪条件导致泥沙从岬角周围泄漏并大量堆积在上游海滩时，就会发生更快的绕流周期（即几个月）。岬角绕流周期发生在多个时间尺度上，包括波浪气候的季节性变化、海岸线进积和后退的年际和十年际周期。厄尔尼诺-南方涛动、太平洋年代际振荡和跨年代际太平洋振荡等大尺度气候驱动因素的变化被观察到会影响研究区岬角绕流低频变化，从而影响主要波浪方向和上游海滩泥沙的供应。理解岬角绕流过程的这种间歇性特征，特别是考虑其周期性及其相关驱动力，对于预测未来的海岸灾害和制定管理策略至关重要。
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