Advantages of beachrock slabs for interpreting high-energy wave transport: Evidence from Ludao Island in south-eastern Taiwan
Advantages of beachrock slabs for interpreting high-energy wave transport: Evidence from Ludao Island in south-eastern Taiwan
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DOI：
10.1016/j.geomorph.2014.09.010
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发表时间：
2015
期刊：
影响因子：
3.9
通讯作者：
A. Lau;J. Terry;A. Switzer;Jeremy Pile
中科院分区：
文献类型：
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作者：
A. Lau;J. Terry;A. Switzer;Jeremy Pile
强台风频繁影响台湾东部。在台湾大陆东南部的一座小火山岛鹭岛西南海岸的大白沙海滩上，大量滩岩板的存在提供了这些风暴产生的高能波浪的沉积物输送能力的证据。有了明确的海滩岩石来源（板片的来源），就可以根据碎屑相对于露头的当前位置轻松区分在上升流或反冲洗流中输送的碎屑。为了从测量的海滩岩板中估计波浪产生的流速，Nandasena 等人提出了巨石传输的流体动力学方程。 （2011）已被重新安排，以便它们适合这种特定的地貌环境，在这种环境中，暴露在原位的海滩岩石露头释放出碎屑，然后这些碎屑可以通过上升到海滩或反冲洗流到邻近的珊瑚礁平台上。这种环境在热带海岸线上很常见，边缘珊瑚礁和海滩主要由生物沉积物组成。在大白沙海滩案例中，将所有测量的海滩岩石板从其源头露头输送到当前位置所需的最低流速为助流 2.18–3.16 m/s 和反冲洗 1.76–3.24 m/s。通过讨论使用海滩岩石碎屑解释波浪行为的优点和局限性，本文提出了研究高能波浪事件的另一种方法，该方法非常适合某些富含碳酸盐的海岸线。
Powerful typhoons frequently affect eastern Taiwan. On Dabaisha beach on the SW coast of Ludao Island, a small volcanic island lying SE off mainland Taiwan, the presence of numerous beachrock slabs provides evidence of the sediment transport capabilities of high-energy waves generated by these storms. With a well-defined beachrock source from which the slabs were derived, it is easy to differentiate clasts transported in run-up or backwash flow based on their current position relative to the outcrop. In order to estimate the wave-generated flow velocities from the measured beachrock slabs, the hydrodynamic equations for boulder transport by Nandasena et al. (2011) have been rearranged so that they are appropriate for this particular geomorphic setting, where exposed in situ beachrock outcrops liberate clasts which may then be transported either by run-up onto the beach or backwash flow onto adjacent reef platforms. Such settings are common on tropical coastlines with fringing coral reefs and beaches comprising mostly biogenic sediments. In the Dabaisha beach case, the lowest flow velocities required to transport all measured beachrock slabs from their source outcrop to current positions are 2.18–3.16 m/s for run-up and 1.76–3.24 m/s for backwash. With a discussion of advantages and limitations on the use of beachrock clasts for interpreting wave behaviour, this paper presents another proxy for studying high-energy wave events that is highly suitable for certain carbonate-rich coastlines.