1 Introduction 1
References 3
Part I Theories and Methods for Soil Conservation Experiments
2 Similarity of Model Experiments 7
2.1 Development of the Experimental Erosion 7
2.2 Purpose and Significance 10
2.3 Similarity Requirements 11
2.4 Experimental Methods and Materials 13
2.4.1 Data for the Prototype Watershed 13
2.4.2 Landscape Simulator 14
2.4.3 Performance of the Landscape Simulator and Data
Collection 19
2.4.4 Executive Process 19
2.5 Results and Discussion 21
2.5.1 Counteraction of the Soil Loss Error Caused by Different Rainfall Intensity 21
2.5.2 Calculation of Soil Loss Scale Number and Relative Ratio 23
2.5.3 Validation of Soil Loss Scale Number 24
2.5.4 Qualitative Analysis of Erosion Depth 25
2.6 Conclusions 26
References 27
3 A Conventional Experimental Technique: Rainfall Simulation 29
3.1 Methods for Simulating the Rainfall 29
3.2 Rainfall Simulators with Thread Droppers or Needle Droppers 31
3.3 Rainfall Simulators with Spouts or Sprayers 36
3.4 Automated Rainfall-Simulation Hall 40
3.5 Conclusions 41
References 41
4 An Innovative Measurement Instrument: Topography Meter 45
4.1 Quantitative Monitoring of Gravity Erosion 45
4.2 Experimental Setup and Methods 47
4.3 Data Processing 50
4.3.1 Method to Calculate Gravity Erosion and Hydraulic Erosion 50
4.3.2 Method to Measure Slope Volume 50
4.4 Results and Discussion 53
4.4.1 Calibration Test for Measurement of the Slope Volume and Coordinates 53
4.4.2 Case Study for an Individual Failure 54
4.4.3 Case Study for the Total Amount of Erosion 56
4.4.4 Limitations and Future Developments 56
4.5 Conclusions 57
References 57
5 How to Conduct an Experiment in the Field: A Portable Laboratory 59
5.1 Difficulties to Conduct a Rainfall-Simulation Experiment in Situ 59
5.2 Design of the Measurement System 61
5.2.1 A Movable Tent for Field Study 61
5.2.2 Operating Principle of the MX-2010-G Topography Meter 61
5.2.3 Structure of the MX-2010-G Topography Meter 63
5.3 Applications in the Landslide Experiments 65
5.3.1 Results of the Landslide Experiments 65
5.3.2 Methods to Obtain Relatively Clear Video 67
5.3.3 Assessment of the MX-2010-G Topography Meter 70
5.4 Conclusions 71
References 72
Part II Soil Conservation Experiments: Case Studies on the Loess Plateau, China
6 A Close Look of the Gravity Erosion on the Loess Plateau of China 75
6.1 Gravity Erosion: Natural Hazard and Soil Erosion 75
6.2 Characteristics of the Loess Plateau 77
6.3 Methods and Materials 78
6.4 Results and Discussion 79
6.4.1 Analysis of the Catastrophic Loess Landslides 79
6.4.2 Soil Erosion Caused by Loess Landslides 87
6.4.3 Urgent Desires and Effective Measures to Prevent Landslides 90
6.5 Conclusions 91
References 91
7 Effects of Conservation Practices on Soil, Water,and Nutrients 95
7.1 Effects of Soil Conservation Practices 95
7.2 Characteristics of the Nanxiaohegou Catchment 97
7.3 Methods and Materials 97
7.4 Results and Discussion 101
7.4.1 Distributions of Water, Soil, Nutrients, and Total Retention Efficiency 101
7.4.2 Retention Ability and Retention Ratio 101
7.4.3 Positive Effects of the Conservation Practices 105
7.4.4 Negative Effects of the Conservation Practices 106
7.4.5 Role of Check Dam in Reducing Soil and Water Loss 107
7.4.6 Future Research Scenarios 108
7.5 Conclusions 109
References 109
8 Sediment-Storage Effects of Check-Dam System in the Small Watershed 113
8.1 Relative Stability and Optimum Programming of Check Dams on the Loess Plateau 113
8.2 Characteristics of the Yangdaogou Catchment 117
8.3 Experimental Methods 118
8.3.1 Runoff Simulation 119
8.3.2 Rainfall Simulation 122
8.4 Results and Discussion 125
8.4.1 Mechanism of the Relative Stability Development 127
8.4.2 Further Research on the Theory of Relative
Stability 130
8.4.3 Comparison of Sediment Loss and Dam-Land Area 132
8.4.4 Comparison of the Water Discharge and Sediment Concentration 134
8.4.5 Relationship Between the Dam-Land Increase and Erosion Reduction 136
8.5 Conclusions 136
References 137
9 Gravity Erosions on the Loess Gully Bank: Avalanche,Landslide, or Mudslide 141
9.1 Impact Factors of the Gravity Erosion 141
9.2 Method and Materials 143
9.3 Results and Discussion 144
9.3.1 Types of Observed Mass Failures 144
9.3.2 Triggers of the Gravity Erosion 146
9.3.3 Prevention and Control Measures 147
9.4 Conclusions 148
References 148
10 A Sensitivity Analysis on the Gravity Erosion on the Steep Loess Slope 151
10.1 Assessment of Soil Erosion Sensitivity 151
10.2 Gravity Erosion on the Loess Plateau 152
10.3 Experimental Methods 153
10.4 Results and Discussion 156
10.4.1 Occurrence and Behavior of the Gravity Erosion 156
10.4.2 Triggers: Rainfall Intensity and Duration 159
10.4.3 Triggers: Slope Height and Gradient 161
10.4.4 Causes of Different Failures: A Concise Discussion 162
10.4.5 Sensitivity Analysis 163
10.4.6 Problems and Suggestions 164
10.5 Conclusions 165
References 165
11 Detecting Fingerprints of Gravity Erosion Drivers: A Laboratory Experiment 169
11.1 A Retrospective Study on the Failure Scar on the Slope 169
11.2 Methods and Materials 172
11.3 Results and Discussion 174
11.3.1 Characteristics of Failure Scars 174
11.3.2 Impact Factors of Failure Scars 177
11.3.3 Sensitivity Analysis 180
11.3.4 Formation Mechanism of Scar Morphologies 181
11.3.5 Effects of Parameters on Scar Forms 182
11.3.6 Hazard Risks Suggested from the Scars 185
11.4 Conclusions 186
References 186
12 Effects of Gravity Erosion on Particle Size Distribution of Suspended Sediment 191
12.1 A Review on the Study of Particle Size Distribution of Suspended Sediment on Steep Slopes 191
12.2 Characteristics of the Liudaogou Catchment 193
12.3 Methods and Materials 193
12.4 Results and Discussion 196
12.4.1 Changes of PSDSS Affected by Gravity Erosion 196
12.4.2 Effects of Gravity Erosion on d50, H, D 198
12.4.3 Changes of Enrichment/Dilution Ratios by Water Erosion and Gravity Erosion 200
12.4.4 Causes of the Changes of PSDSS 201
12.4.5 Gravity Erosion and Hyper-Concentrated Flows 203
12.5 Conclusions 205
References 205
13 Tunnel Flow and Erosion Processes in an Experimental Catchment 209
13.1 A Brief Introduction on the Tunnel Erosion 209
13.2 Characteristics of the Wangjiagou Catchment 210
13.3 Field Study Methods 211
13.4 Results and Discussion 214
13.4.1 Hydrological Processes of Tunnel Flows 214
13.4.2 Sediment Processes of Tunnel Flows 219
13.4.3 Tunnel Sediment Contributions to Catchment Yield 222
13.5 Conclusions 223
References 223
Additional Material 227
