近岸海流對物質擴散及沉積物傳送相當重要，但因為複雜的潮流、風應力及波浪之共同作用，至今台灣海峽淺水區域的近岸流系統仍沒有被清楚的了解。此外，本計畫為了增強科學研究對台灣社會的影響性，研究地點包含了觀新藻礁保護區域海域，此區域除了自然作用力外，亦受到人為開發的影響。本計畫的研究目的在探討自然營力的潮汐、季節風(夏季及冬季)、波浪之驅動力對近岸海流的影響，也希望探討人為突堤對近岸海流的影響。第一年的研究計畫已成功驗證我們建立的數值模式，模擬結果與現場觀測的結果吻合度相當好。本年度的研究計畫我們預計持續進行現場觀測跟數值模擬。台灣海峽北部淺水區域(水深1到4米)的海流將使用潮波流儀來進行現場觀測，觀測地點包含遠離突堤及靠近突堤的兩個點位。將使用Delft 3D數值模式重建近岸流的系統，此驗證過的模式將利用來進行數個理想化的情境模擬，用以探討潮流、風、波浪、及人為結構物的影響。特定的研究問題包含：1. 在夏季及冬季季風下，驅使台灣海峽北部淺水區域近岸海流的機制；2. 海流在大小潮及漲退潮時的差異變化特性；3. 淺水區潮流及殘餘流的特性；4. 突堤效應對近岸海流的影響；5. 在結構物附近，潮流引起的相位渦流及波浪引起的漩渦之交互作用。瞭解藻礁海域的海流驅動力對保護藻礁相當重要，此研究計畫可視為深入瞭解觀新藻礁淺水海域海流趨動力的先驅基礎研究。 ;Nearshore currents are important for material dispersion and sediment transport, yet, not well understood in shallow waters of Taiwan Strait where complicate nature forcing mechanisms such as tide, wind, and wave coexist. For enhancing the scientific impacts on Taiwan society, our study site includes a conservation area, the Guanxin algal reef, where is affected by coastal development (coastal jetty). The aim of the project is to study the effects from nature forcing of tide, monsoon wind (summer and winter), and wave and artificial effects due to construction of coastal jetty on the nearshore currents. The results of the first-year project have shown that our modelled results agree well with the observational results. In the proposed research year, we will continue to study the nearshore current with approaches of field observations and numerical modeling. Nearshore currents in the shallow water depth of 1 to 4 m in northern Taiwan Strait will be observed using ADCPs at sites close to and far from the coastal jetty. A numerical model-Delft 3D will be used to reconstruct the nearshore circulations. The verified model will be used to perform several idealized scenarios, i.e. with and without the nature forcing from wind, tide, and wave, and with and without artificial effects due to coastal structure. Specific scientific issues for studying include: 1. mechanisms driving nearshore currents in shallow waters of northern Taiwan Strait in summer and winter monsoon seasons. 2. Variation of currents in spring, neap, flood, and ebb tidal phases; 3. Understanding the tidal and residual currents in shallow waters; 4. Effects of coastal jetty on the nearshore currents; 5. Interaction between tidal-induced phases eddies and wave-induced eddies near the coastal jetty. Understanding of forcing mechanisms at the reef region is important to conserve the reef. Our study serves as a pioneer to investigate the nature forcing mechanisms that driving the shallow-water nearshore current at GuanXin algal-reef region.
