Title Page
ABSTRACT
국문 초록
Contents
NOMENCLATURE 14
CHAPTER 1. INTRODUCTION 16
1.1. Landscape Evolution Problems 16
1.2. Mechanism of Sediment Transport 17
1.3. Study Objectives 18
CHAPTER 2. LITERATURE ABOUT SEDIMENT TRANSPORT 21
2.1. Types of Sediment Transport 21
2.2. Grain Size 22
2.3. Transport Rate 24
2.4. Incipient Motion 27
2.5. Layering Algorithms 29
CHAPTER 3. MODEL DEVELOPMENT 31
3.1. LEGS 31
3.2. Fluvial Processes 32
3.3. Layering Algorithms 37
3.3.1. Erosion 37
3.3.2. Deposition 39
CHAPTER 4. MODEL PERFORMANCE 43
4.1. Simulation Condition 43
4.2. Fractional Transport Rate 47
4.3. Layering Algorithm Sensitivity 51
4.4. Computation Time Comparison 55
CHAPTER 5. LONG TERM SIMULATION 57
5.1. Simulation Condition 57
5.2. Topographic Relief and Sediment Yield 57
5.3. Grain Size Distribution and Limitation 63
CHAPTER 6. CONCLUSION 75
REFERENCES 77
Table 1. Computation time (sec) for each equation. 56
Table 2. Local slope of highest point for each iteration in the case of 2mm and 8mm. 62
Figure 2.1. An illustration of cumulative curve for grain size distribution. 23
Figure 2.2. Particle-weight effect (solid line), hiding-sheltering effect (broken line) and rollability effect (dotted line) of large particle (A) and small particle (B) in mixed-size grain. 28
Figure 3.1. Comparison of surface-based sediment transport equation of Parker et al (1982) and Wilcock and Crowe (2003). 35
Figure 3.2. Comparison of hiding function of Schvidchenko et al (2001) and Wilcock and Crowe (2003). 36
Figure 3.3. Dimensionless reference shear stress according to the sand ratio in the streambed. 36
Figure 3.4. Schematic of erosion within the surface layer (The dotted line represents eroding sediment). 38
Figure 3.5. Schematic of deposition within the surface layer in MT algorithm (The dotted line represents deposited sediment). 41
Figure 3.6. Schematic of deposition within the surface layer in ML algorithm (The dotted line represents deposited sediment). 42
Figure 4.1. (a) Initial domain of simulation and (b) expanded view of initial domain. 46
Figure 4.2. Sediment transport rate of 2mm in (a) homogeneous condition and (b) heterogeneous condition 49
Figure 4.3. Sediment transport rate of 4mm in (a) homogeneous condition and (b) heterogeneous condition. 50
Figure 4.4. Sediment yield of two layering algorithms. 53
Figure 4.5. Erosion schematic diagram after new deposited material is deposited by (a) MT algorithm and (b) ML algorithm, respectively. 54
Figure 5.1. Topographic relief of three cases. 60
Figure 5.2. Contour line and flow path for each iteration in the case of 2mm and 8mm. 61
Figure 5.3. Sediment yield for each case of three cases. 62
Figure 5.4. Elevation and median grain size in 2mm and 8mm condition 69
Figure 5.5. Elevation and median grain size in 2mm, 4mm, and 8mm condition 74