| 摘要: | 海岸的水動力與紊流對近岸海洋環境的沉積物傳輸、地質、生地化、生物及生態系統相當重要。因為現場風、波浪、潮流及多尺度流動特性等複雜性，至今學界對此問題難有好的量化研究。根據文獻回顧與計畫主持人最近的研究成果，波流作用下的自然粗糙海床上的紊流特性之科學知識仍相當缺乏；因此，本研究計畫擬以野外現場實地觀測的方式，來探碎波帶內、波流作用下自然粗糙海床上的紊流特性。根據以往經驗，我們可以成功地在有波浪及平均流的海域進行高品質的紊流現地觀測及量化研究。本研究計畫預計在桃園海岸的藻礁自然碎波帶內粗糙海床上進行紊流混攪機制的研究。本計畫預計使用壓力計、流速儀及攝影機，來量測在這些粗糙海床上的風、波浪、流、紊流、及碎波等特性。新式的高頻與高解析度的流速與海流剖面儀將使用來獲得細緻的流場結構。本計畫希望藉由比較沒有碎波與碎波帶，與在粗糙底床與沙地上的觀測結果，來了解碎波與底床粗糙度如何影響淺水區的紊流與波浪剪應力。 ;Understanding the hydrodynamics and turbulent flows is crucial in modeling and monitoring the sediment transport, geological, biogeochemical, and biological processes in nearshore environments. It is difficult to have a quantitative study due to the complex process of wind, waves, tides, wave-current interaction and multi-scale flow dynamics. Based on the up-to-date literature review and our recent efforts, wave-current turbulence in nature rough seabed of coastal environments are largely unexplored. As a result, we propose to study the wave-current turbulence, wave stress under surf-zone breaking waves over nature rough seabed in fields. We have shown the ability and experiences to perform high-quality field experiments to observe turbulent mixing in shallow waters in the challenging coastal zone where waves and currents coexist. In this proposal, field experiments and data analysis will be conducted to explore the mechanisms driving the turbulent mixing under surf-zone breaking waves over the nature rough seabed over an algal reefs, Taoyuan coast. A suite of instruments including pressure sensor, velocimetry, and video camera will be deployed along a line in the cross-shore direction to measure the wind, waves, currents, turbulence, and wave breaking over the reef. New types of high-frequency and high-resolution velocimeters called velocity profilers and current profiler will be used to obtain detailed flow structures. This project aims to understand how wave breaking and bottom roughness affecting the distributions of turbulent and wave stresses in shallow waters. This could be examined by comparing the measured quantities under breaking and non-breaking waves and on the reef flat and sandy bottom, respectively. |
