臺灣本島受地理環境影響，高山地形面積遼闊且坡地與河岸地質不穩定，常為集水區帶來豐厚的沖積沙源；而 高山多為南北走向，總和以上因素，導致臺灣河川含沙濃度極高，成為西部河口海域地區主要沙土來源，並且對河口及下游沿海地形的穩定扮演重要的角色。
而近數十載以來，曾文溪口與沿海地區因集水區上游水庫、防沙壩等水土保持設施的興建及河岸河床地整治，導致河川沙源已不復以往；沿海地區的港灣、突堤等外凸結構物對於沿岸漂沙的阻攔；束洪效應對於沖積三角洲的影響，使得海岸線長期呈現侵蝕狀態。而河口作為河海交會處，因受潮流、波浪、河川入流與不規則地形…等因素與其交互作用所影響，使得河口相鄰近海域之水理運動與輸沙行為過於複雜，也因此難以預測與模擬。
本研究使用數值模式Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST)中的區域海洋環流組件Regional Ocean Modeling System(ROMS)，針對曾文溪口與近岸海域於2018年冬季(11月21日至11月28日)以及2019年夏季(8月22日至9月4日)期間的實測資料進行場景模擬與驗證，且根據模式結果的時序列比對下，具有一定的合理性。隨後延續模式的場景與設定，模擬在受到潮汐與不同量級河川流量的作用下，區域內相異粒徑的輸沙趨勢與行為，並使用不同粒徑泥沙的模擬結果歸結出不同粒徑泥沙再懸浮的範圍，以及向北傳輸的程度。

The geological environment of Taiwan Island covers a vast area of high mountain terrain along with unstable slope and riverbank geology, which often provides a rich source of alluvial deposits in the watershed; and the high mountainous terrain usually runs north-south. As a result, sediment concentration in Taiwan's rivers can be a main source of sediment in the western region of Taiwan and play an important role in stabilizing the estuarine and downstream coastal terrain.

This study use the Regional Ocean Modeling System (ROMS), the regional ocean circulation component of the numerical model Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST). To November 28) and the measured data during the summer of 2019 (August 22 to September 4) for scenario simulation and verification, and based on the time series comparison of the model results, it is reasonable to a certain extent. Subsequently, keep the scenarios and settings of the model to simulate the sand transport trends and behaviors of different particle sizes in the region under the action of tides and river flows of various magnitudes. However, if the high tide is in the base flow period, the seawater may flow into the estuary, and the low tide will accelerate outward regardless of the flow rate. Results for the various particle sizes show that the primary difference is the area where settlement and resuspension occur continuously in the delta plain and the distance of northward transport. In addition, although there was sediment deposition on the northern estuary during the flow event, after the flooding, most sediment will still return to the outer estuary by tidal drive after flooding.

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