海下辮狀河道之地形成因通常被認為是異重流挾帶大量沉積物在海下堆積所形成，在辮狀沉積地形裡多蘊含豐富之石油、天然氣及黃金等高度經濟價值資源。然而海下辮狀河道之相關文獻相當有限，目前非常缺乏形成海下辮狀河道之物理機制，只能透過陸上辮狀河道之成因進行推測。因此本研究希望透過小尺度之物理模型實驗來探索海下辮狀河道之形成機制與其形貌特色。本文以鹽水做為異重流，塑脂砂做為砂材進行試驗，透過每五秒一次的高解析度間隔攝影及雷射切頁掃描，完整記錄海下辮狀河道之地形演化過程，並透過數位影像處理之技術建立系列高精度之數值高程模型。
實驗結果顯示，以異重流流量、供砂量、底床坡度三者為操縱變因之實驗可成功重現海下辮狀河道形貌。在形貌變化上，海下辮狀河道藉由異重流挾帶泥砂運移，會產生大量的加積作用，異重流主要河道流動於堆積地形上並在實驗砂箱內產生大量分流之複數河道與支流匯集等現象，在實驗中可觀察到大量河中砂洲出現、自然堤形成與河道改道等現象，這些形貌特徵相似於陸上辮狀河道之流動特色；透過分析發現海下辮狀河道之辮狀指數會落在0.4至0.7之間，趨勢線會收斂並接近0.5，此結果與陸上辮狀河道實驗非常吻合。

Submarine braided turbidite are known as important submarine deposits for the drilling of gas, petroleum and gold reservoirs. Previous studies pointed out sediment-laden turbidity currents could be one of the major sources. However, little research addresses submarine braided turbidity currents. Most of the understanding of braided turbidities are still based on terrestrial braided rivers. In this study, we use small-scaled physical experiments to investigate the evolution of saline-driven submarine braided channels on an inclined plastic bed. Detailed evolving processes are recorded by time-lapse photography. Bed topography of each experimental stage is then scanned and reconstructed to get high resolution digital elevation models. Our results show that the bed forms dynamic submarine braided channels under altering turbidity flow discharge and slope. The braided channels diverge and converge to form several active channels and bars. This characteristics similar of terrestrial braided rivers. The ratio of braiding index from experiments stabilized at 0.5 at equilibrium. We hope our results can stimulate new questions and motivate more future research.

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