淡水河河口波浪潮汐所引起之漂沙三維數值模擬

Three-dimensional simulation of wave-tide sediment transport in Danshui River

呂岱華(Dai-Hua Lu)

指導教授 ： 周逸儒

國立臺灣大學/工學院/應用力學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201702726

摘要

本研究是使用三維海洋模式SUNTANS結合非結構性網格來模擬淡水河下游河口及其鄰近海岸的輸砂特性。首先，將對模式進行自由液面、鹽度變化、波高變化與懸浮泥沙濃度進行驗證，再利用驗證完成之模式觀察河川中懸浮泥沙在水體之運動，並探討淡水河口及其鄰近海岸之懸浮泥沙受潮汐、波浪的影響。結果顯示，在相同潮汐與入流條件下，有考慮風浪將增加懸浮泥沙的濃度，其原因是由於在有考慮風浪的情況下，風與波浪皆會影響底床淘刷，使得較大量的底泥被懸浮至水體中。接著，在考慮三種不同風向的情況下，我們發現北風會在台北港北防波堤處有最大的懸浮泥沙量，其原因是因為波浪正交於海岸線，使的底泥有最大的懸浮量值，且由結果顯示，波浪輻射應力為使淡水河口及其沿岸產生高濃度漂沙的主要原因。

關鍵字

淡水河 ； SUNTANS ； 輸砂 ； 潮汐 ； 風浪 ； 台北港

並列摘要

In this study, a three-dimensional unstructured-grid numerical SUNTANS was used to simulate the sediment transport at the Danshui river mouth and surrounding coastlines. To validate the model, the free surface, salinity, wave height, and suspended sediment concentration (SSC) were tested against the field data. The effects of tides and waves on sediment transport at the river mouth and surrounding coastlines were discussed using the validated model. Results showed that under the same condition of tides and inflow, SSC increases in the presence of waves. The main reason of this phenomenon were winds and radiation stresses. After considering three different wind directions, we found that north wind result in the highest SSC occurring at north jetty of the Taipei port, where the wave direction is perpendicular to the coastline, and the radiation stresses are responsible of high SSC at the river mouth and surrounding coastlines.

並列關鍵字

Danshui River ； SUNTANS ； Sediment transport ； Tide ； Wave

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