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A Study on the Sediments Distribution at Southwest Sea Area of Chang-Hua
|Authors: ||Hsing-Yu Wang|
|Contributors: ||NTOU:Department of Harbor and River Engineering|
|Keywords: ||彰化海岸;漂沙分佈;DHI MIKE-21|
|Issue Date: ||2011-11-23T03:18:41Z
|Abstract: ||海岸地形變遷主要受海岸地形變化與潮波流等海域營力所建構的近岸動力系統主導。彰化海岸因處臺灣海峽束縮段，潮差大且水流強勁，復因區內有高含沙量之濁水溪注入海中，海岸漂沙活動相當活躍。由於彰化海岸地形平緩，潮間帶可達數公里，近年來海岸空間規劃利用倡議不斷，為因應未來海岸空間管理之需，及避免開發規劃不當衍生海岸復育問題，本研究進行海域潮汐、波浪、海流及漂沙等現場觀測作業以掌握彰化西南角海域漂沙分佈特性，並將現場實測資料提供作為DHI MIKE-21漂沙模式率定參數之用，模擬海岸漂沙分佈特性。 由現場實測資料顯示，本研究區域夏季底床質粒徑分佈以沿岸方向距河口越遠粒徑越粗，離岸方向則無規律性；冬季粒徑分佈以離岸方向水深越深粒徑越細，沿岸方向距河口越遠粒徑則越粗。另將現場觀測資料與模式計算結果比較後可發現，碎波帶內懸浮質受波浪能量集中近岸影響，漂沙運移優勢方向以向離岸方向為主；碎波帶外之漂沙運移主要受潮流運動主導，優勢方向以平行岸線方向運動。|
Coastal terrain is mainly altered by nearshore hydrodynamics system such as changes in topography. Locating on the narrow section of the Taiwan Strait, active coastal sand drift is found on the coastline of Chang-Hua because of its large tidal range, strong current, and high sediment of Cho-Shui River into the sea. As the flat coastal terrain of this area, the intertidal zone is up to several kilometers. Since many advocates of the need to future coastal management and to avoid inappropriate development from coastal restoration, the main purpose of this study is to use the data of the area tidal, wave, current, and sand drift to understand the characteristics of the distribution of the sediment in the southwest of Chang-Hua. Furthermore, the study utilized the on-site data to provide DHI MIKE-21 to simulate the distribution of the sand drift. Based on the on-site collective data in the study area, the particle size on the seabed in summer gets larger along the coast when it is farther away from the river mouth and no regular offshore direction is found. Moreover, the particle size in winter gets finer offshore and larger along the coast when it is farther away from the river mouth. After comparing the on-site collective data and calculation from stimulating model, the results show as the followings. First, the suspend load within the surf zone is affected by the nearshore wave energy and the advantage of the sediment transport is mainly to the offshore direction. Second, the drift outside the surf zone is mainly led by the trend shift and the advantage moving direction is parallel to the shoreline.
|Appears in Collections:||[河海工程學系] 博碩士論文|
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