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作者 : 劉安頤
作者簡介 :
論文主題 : Advantages of beachrock slabs for interpreting high-energy wave transport: Evidence from Ludao Island in south-eastern Taiwan
出版年份 : 2014
論文摘要 :
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-energywaves generated by these storms. With a well-defined beachrock source fromwhich the slabswere 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 ydrodynamic 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 clastswhichmay then be transported either by run-up onto the beach or backwash flowonto adjacent reef platforms. Such settings are common on tropical coastlineswith 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.
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