在複雜的板塊運動和氣候的交互作用下，地表形貌隨時間而改變，並產生數量可觀的沈積物，由陸地傳輸到海底，每年約有超過200億噸的輸出到海洋，其中約有70%的河流沈積物由造山運動活躍的南亞進入太平洋和印度洋。此外，山棲型小河沈積物的輸出對海洋沈積物的貢獻一直被低估，因此，有必要透過山棲型小河的沈積動力研究，重新估算此類小河的沈積物入海的收支量。
高屏溪具有全世界第12高的沈積物產率，且與相鄰只有1公里的高屏海底峽谷直接相連，而高屏海底峽谷又切入高屏陸棚與陸坡，匯入下面的馬尼拉海溝後進入南海盆，因此，這是一個研究源到匯之沈積物動力的理想場域。
由於高屏河-海系相當複雜，本論文運用多種不同的研究工具與手段，調查了高屏溪下游河口和沖淡水區的水文及水動力之時空變化；而在峽谷區，則用沈積物收集器搭配温深鹽儀、濁度計、都卜勒流剖儀來研究枯水期、豐水期、以及颱風過後的沈積物動力作用。
調查結果顯示，河川涇流與潮汐的交互作用下，在河口區產生了上層向外而底層向內的兩層式的河口環流，同時，在離河口約1.5 km處，有一個動態的沈積顆粒屏障，是海水入侵最裏的位置。除非是暴洪事件，一般狀況下河川輸出的沈積物會隨沿岸噴射流擴散到沿岸地區沈降下來。在高屏海底峽谷內，細顆粒沈積物通常會懸浮在峽谷底層，形成底霧濁層，此時的懸浮沈積物的傳輸趨勢是往峽谷頭向上輸送；另一種在洪水暴發後產生的高濁度重力流，將陸地上的沈積物透過海底峽谷直接運送到深海去，這種偶發的現象，亦將較輕的暖水帶到深海底。

The complex interplay between tectonic and climate activities shapes the Earth’s surface and produces large amounts of sediments conveying from land to the sea. Therefore, more than 20 billion tons of sediments is exported to the ocean each year. There is approximately 70% of the global fluvial sediment discharge from the orogens in southern Asia and high-standing islands fringing the Pacific and Indian Oceans. The contribution by small mountainous rivers (SMR) to the world ocean’s sediment budget in this region, although significant, has often been underestimated. Therefore, the research in the sediment dynamics is necessary for evaluating the sediment budget from SMR to the basin.
The Gaoping River (GPR) has high sediment yield whose ranking is the 12th in the world and connects to the head of the Gaoping Submarine Canyon (GPSC) just 1 km apart. Moreover, the GPSC cuts through the Gaoping shelf and slope and merges into the Manila Trench which eventually links to the South China Sea. Therefore, this dispersal system is an ideal play for studying the dynamics of the source-to sink (S2S) processes.
This dissertation presents field investigations in the GPR estuary, hypopycnal plume area, and GPSC. Because of the complexity of the GPR-GPSC dispersal system, multidiscipline and different approaches were adopt in the different region in the system. In the estuary and the plume area, both temporal and spatial schemes were conducted to measure the hydrodynamic, hydrographic, water samples, and sediment samples. In the GPSC, three sediment trap moorings with CTD, OBS, and ADCP were deployed during the dry, flood season, and after the typhoon, respectively.
In the estuary, the interaction between river flow and tidal oscillation produces two layered circulation which flows downstream in the top-core layer and upstream in the near bed layer. A dynamic sediment barrier was found in the lower reach of the estuary. Except extreme floods, river effluents spread over the coast seawater through the hypopycnal processes. Most effluent sediments transport along the coastal jet and deposit in the coastal or near-shore ocean. In the GPSC, canyons, major sediment transport and rapid sediment deposition occur in the benthic nepheloid layer (BNL). Sediments in the hyperpycnal plume are trapped in the head region of the submarine canyon during the normal condition and flow down the canyon conduit to the deep basin during extreme floods. We also captured the warm water and suspended sediment carried by passing turbidity currents that originated in the adjacent GPR.

論文審定書 i
摘　　要 ii
Abstract iii
誌　　謝 v
Contents vi
List of Figures ix
List of Tables xvii
Chapter 1 Introduction 1
1.1 River-sea systems in the source-to-sink perspective 2
1.2 Sediments contribution from small mountainous rivers to the ocean 3
1.3 Aims 4
Chapter 2 Study area and methods 5
2.1 Study areas 5
2.1.1 Fates of Taiwan Rivers 5
2.1.1.1 Influence of Taiwan orogeny 5
2.1.1.2 Influence of monsoon and typhoons 6
2.1.2 The Gaoping River (GPR) 8
2.1.2.1 Geographic settings 8
2.1.2.1 Hydrological characteristics 10
2.1.3 Gaoping Submarine Canyon (GPSC) 12
2.1.3.1 Geological setting 12
2.1.3.2 Geographic and geophysical properties in the GPSC 14
2.2 Innovative techniques 15
2.2.1 Estimation of floc density and porosity 15
2.2.1.1 Floc porosity (n) estimation 17
2.2.1.2 Bulk floc density (ρF) estimation 18
2.2.1.3 Necessary for on-board filtration 18
2.2.1.4 Suggestions for further application 19
2.2.2 Modification of Sediment traps 20
2.2.2.1 Problems for fixed-volume type sediment trap 20
2.2.2.2 Advantages of the Non sequential sediment traps (NSST) 21
2.2.2.3 Standard operation procedure (SOP) of the NSSTs’ sediment sampling 23
2.2.2.4 Improvements on the NSST 25
2.2.2.5 Suggestions for future modification 26
2.3 Sampling locations and methods of field studies 28
2.3.1 GPR estuary 28
2.3.2 GPR mouth 29
2.3.3 GPSC 30
2.3.3.1 Sediment trap mooring deployment in the dry season 30
2.3.3.2 Sediment trap mooring deployment in the flood season 32
2.3.3.3 Sediment trap moorings deployment after Typhoon Fanapi 35
Chapter 3 Results 38
3.1 Particle dynamics in the estuary 38
3.1.1 Three layered estuarine circulation 38
3.1.2 Dynamic barrier of the seawater intrusion 39
3.2 River plume dynamics 40
3.2.1 Hypopycnal plume structure of the GPR 40
3.3 Dynamics of settling particles in the GPSC 43
3.3.1 Sinking particle dynamics in the normal condition 43
3.3.1.1 Tidal dominated regime 44
3.3.2 Hyperpycnal turbidity currents (HTC) in the GPSC 46
3.3.2.1 Waxing and waning signatures in the turbidity currents 47
3.3.2.2 Hyperpycnal turbidity currents in the wake of typhoon floods 49
Chapter 4 Discussions 59
4.1 Interplay between the GPR plume and GPSC internal tidal flows 59
4.2 Capturing hyperpycnal turbidity current in the GPSC 65
4.3 The retarded HTC by the internal tidal flow 67
4.4 Estimate the terrestrial fraction carried by the HTC 68
Chapter 5 Conclusions 69
References 70

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