水下辮狀河道是受到突發和多變的濁流事件趨動而形成的水下河道。本研究利用小尺度物理實驗模型，透過飽和鹽水模擬深海濁流，以探討水下辮狀河道受到不同的水文歷線影響下之形貌演化。實驗結果顯示，水下辮狀河道之形貌會隨著流量變化而改變，在設計水文歷線下之形貌變化包含：(1)當流量漸增時，異重流匯聚並下切形成較深之河道，發展由單一主河道控制且河幅寬廣之形貌特徵；(2)當流量漸減時，異重流從主河道開始切割並向外擴張，發展出由多條河道與沙洲交織而成的水下辮狀河道；(3)當流量維持穩定時，水下辮狀形貌對應流量發展出穩定之形貌趨勢。此外，當流量漸增時，動態河道辮狀指數(active braiding intensity, BIA)會下降；當流量漸減時，動態河道辮狀指數則會上升；當水文歷線保持穩定流量時，動態河道辮狀指數會以臨界時間(critical time, Tc)為界，分成兩個階段：(1)河道發展上升段，動態河道辮狀指數會隨時間持續上升；(2)穩定發展段，動態河道辮狀指數則為趨於穩定。最後，本研究透過二維水理模式(iRIC)，以實驗之地形資料為起始地形，並給定實驗中率定之流量參數進行動床數值模擬。透過敏感度分析可以率定出各項參數，並將模擬結果與實驗結果比較。雖然初步的模擬成果無法與實驗結果完全相符，但是可以藉由無因次參數探討模式與實驗結果之關聯性，分析之成果皆有助於推展水下辮狀河道之形貌動力學。

The development of submarine braided channels is affected by sudden and variable turbidity events. In this study, we used a small-scale physical model to explore the effects of different hydrographs on the submarine braided channels, and conducted experiments with three different hydrographs and constant flow to be control group. According to different flow settings, divided into simple hydrograph, semi-simple hydrograph, and compound hydrograph.

From the experiments results, we found that no matter what type of the hydrographs, the inflow will dominate the morphology development of the submarine braided channels. With the inflow increase, a single channel morphology will be formed, and the morphology of the submarine braided channels is less active; when the inflow decreases, the density currents will cut and incise to expends outward, developing a complex braided channel network; under the constant flow rate, the morphology of the submarine braided channel will be divided into two phases, increasing phase and stability phase, separately.

In addition, we simulated the evolution process of the submarine braided channel through a two-dimensional hydraulic model (iRIC). We calibrated the sensitivity analysis, and compared the experimental results with the simulations. Although the results of simulation cannot fully present the actual current distribution of flow, we can used dimensionless stream power or active braiding intensity (BIA) to discussed the trends of submarine braided channels with simulated and experimental results. These analysis results are helpful to promote the research on the morphodynamics of the submarine braided channels.

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