| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 99 === 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.
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