| 摘要: | 本研究旨在探討第三天然氣接收站對於桃園海岸流場之影響。第三天然氣接收站（簡稱三接港）規劃建置於桃園市大潭工業區沿岸，其設計以棧橋自陸側延伸，連接三接港於離岸海域。新建的結構物因局部遮蔽原先水流與波浪，將使桃園近岸的海流與波浪環境產生改變，從而影響該處的漂沙趨勢及沿岸地形變遷。為了解三接港對近岸波流場的影響，本研究使用二維非結構性網格數值模式Delft3D FM模擬桃園近岸潮波流場受海上結構物影響之變化。研究首要透過與ADCP潮波流儀實測值比較，確立Delft3D FM模擬近岸深度平均波流場之能力，並了解由潮汐、風及波浪應力共同作用下的近岸波流場空間變化；繼而以該具高度重現性的數值模式進行現況模擬以及三接港建置後之情境模擬，環境條件設定夏季、冬季兩種季節，討論不同季節的風浪環境下，三接港建置前後的近岸水動力變異。由模擬結果可知，波高與底床剪應力有相似的變化趨勢，兩者於建港後在波浪受三接港遮蔽處均有下降的情形。三接港港形設計使其與陸側所夾之沿岸海域內的流場、波高、底床剪應力在模擬結果產生空間上的變化：東側棧橋周圍水流因水道收窄而匯集、流速增強，最西南側則因遠離棧橋、位居港形開闊處而在平均流速上稍微減緩。除空間上的變化，左右不對稱的港形亦造成漲退潮時期及夏、冬季節上有不同的流速流向及波高、底床剪應力的模擬差異。;This study aims to investigate the impact of Guantang liquefied natural gas (LNG) seaport on hydrodynamic at the coastal area in Taoyuan city. The LNG seaport, which is located at offshore area and connected to land by a trestle bridge, is proposed for the Guantang Industrial Area along the coast in Taoyuan. With the new structure on coastal area, the flow and wave fields in adjacent sea may evolve differently and result in change of sediment transport and nearshore morphology. To understand the impact of LNG seaport on nearshore current and wave fields, this study uses an unstructured-grid numerical 2D model (Delft3D FM) to analyze the change of the flow and wave fields. First, the capabilities of Delft3D FM in simulating the depth-averaged flow and wave fields around coastal area is confirmed via comparing with observed data from ADCP. Thus, we can understand the spatial variability of flow and wave fields around the coastal area with the tide, wind and wave. Then, scenario models, including original case (without LNG seaport) and LNG seaport case in both summer and winter season, are set up to discuss the impact caused by LNG seaport. As for model results, both significant wave height and bed shear stress reduce in the sheltered area of LNG seaport. The trumpet-shaped LNG seaport, which has larger opening at western side, results in the spatial variations of velocity, wave height and bed shear stress. For example, current may accelerate in eastern side since the narrow gaps under trestle bridge, and slowdown in western side due to the wide opening. Beside the spatial variations, during different tidal phases or different seasons, the impact resulted from the asymmetric of LNG seaport also manifests itself in various changes of the flow direction or velocity, wave height and bed shear stress. |
