異重流(或濁流)是陸緣沉積物被帶往海底峽谷及深海平原之重要傳輸媒介，同時也是影響海底峽谷形貌演化的重要因素。雖然海底峽谷是大陸棚上的重要特徵，但是關於海底峽谷之起源及發展至今仍了解有限。本研究透過一維的物理模型實驗以探究異重流下切海底峽谷的機制及其演化過程。實驗模擬海底峽谷之縱剖面，透過連續的異重流及持續增加的地勢差距兩項機制，讓我們有機會重現在持續發展的大陸坡上，受異重流下切之一維海底峽谷演化過程。實驗過程中，我們以間隔攝影記錄海底峽谷完整的演化過程，並透過數位影像處理技術獲得定量之地形資料。我們追蹤峽谷頭隨時間之變化過程，並從中觀察海底峽谷下切機制與掏刷坑之關係。實驗結果發現海底峽谷之剖面於每個演化階段的後期，都會達到一個穩定的底床坡度，且此穩定剖面經無因次化分析後，皆出現高度之自我相似性。我們也求得不同流量與掏刷坑波長之趨勢，並計算異重流沿著地形剖面之密度福祿數變化。期待本研究之初步成果能夠對海底峽谷之生成與演化做出進一步的了解，也期許此成果能引發更多研究投注在海底峽谷之形貌動力學領域。

Hyperpycnal flows (or turbidity currents) are important in oceanic transportation, they carry subaerial turbidites into deep sea area and are also essential to submarine canyon development. Although submarine canyons are ubiquitous, the mechanism of canyons evolution is still a matter of debate. In this study, one dimensional micro-scale tank experiment was conducted to investigate the mechanism by which turbidity currents erode and incise the canyon floors. During the process of the experiment, we use time-lapse photograph to record the overall process of canyons’ evolution, and analyze them by image analysis methods to obtain quantitative topographical data. The experiment results indicate that submarine canyons will reach stable slope eventually in each evolution period with the growing of continental slope. The result also shows highly self-similarity in these cross sections by dimensional analysis. Furthermore, by tracing the tine series of bedform profiles we observe the correlation between the scours' wavelength and flow rate. Base on this finding, we calculate the Densimetric Froude number of turbidity currents along the section and manifest them to be supercritical flow. Among such analysis above, we hope that this study can facilitate the understanding of submarine canyons and arise more attention toward morphological study.

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