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List of Contents
Page
Acknowledgements... iii
Abstract in English... vi
Abstract in Thai... viii
List of Tables... x
List of Figures... xiv
Chapter I Introduction... 1
1.1 Background... 1
1.2 Rationale... 2
1.3 Objectives... 2
1.4 Assumptions... 3
Chapter II Literature Review... 4
2.1 Concept of erosion... 4
2.2 Soil erosion driving forces and its studies in the northern Vietnam 4 2.2.1 Driving forces of the soil erosion... 4
2.2.2 Measuring the soil loss... 6
2.2.3 Measuring the losses of nutrients... 6
2.2.4 Soil erosion modeling... 7
2.3 Model for soil erosion study... 8
2.4 Roles of GIS technology in soil erosion studies... 9
2.5 Universal Soil Loss Equation (USLE) ... 10
2.6 Soil Loss Estimation Model for Southern Africa (SLEMSA) ... 19
2.7 Morgan, Morgan and Finney Model (MMF) ... 22
2.8 Model comparison... 26
2.9 Extra production cost estimation... 27
Chapter III Study Area... 31
3.1 Physical characteristics... 31
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3.1.1 Geographical location and administrative setting... 31
3.1.2 Topographic conditions... 33
3.1.3 Land use characteristics ... 35
3.1.4 Soil types... 37
3.1.5 Rainfall regime... 40
3.1.6 Direction of the surface runoff... 40
3.2 Socio-economic conditions... 41
3.2.1 Population growth... 42
3.2.2 Shifting cultivation and agriculture... 43
Chapter IV Research Methods... 44
4.1 Data collection... 45
4.2 Soil Loss Estimation Models... 45
4.2.1 Universal Soil Loss Equation ... 45
4.2.2 Soil Loss Estimation Model for Southern Africa ... 50
4.2.3 Morgan, Morgan and Finney Model... 52
4.3 Model comparison... 53
4.4 Extra production cost estimation... 54
Chapter V Results and Discussion... 56
5.1 Universal Soil Loss Equation... 56
5.1.1 Factor maps... 56
5.1.1.1 Rainfall erosivity index... 56
5.1.1.2 Soil erodibility index... 57
5.1.1.3 Factors of slope length and slope steepness... 58
5.1.1.4 Crop management factor... 59
5.1.2 Spatial distribution of the potential soil loss... 60
5.2 Soil Loss Estimation Model for Southern Africa... 62
5.2.1 Factor maps... 62
5.2.1.1 K factor... 62
5.2.1.2 Topographic factor... 64
5.2.1.3 Crop management factor... 65
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5.2.2 Spatial distribution of the potential soil loss... 66
5.3 Morgan, Morgan and Finney Model... 68
5.3.1 Factor maps... ... 68
5.3.1.1 Soil detachment index... ... 68
5.3.1.2 Kinetic energy of rainfall... ... 70
5.3.2 Spatial distribution of the potential soil loss... 72
5.4 Model comparison... ... 74
5.5 Extra production cost estimation... ... 79
5.5.1 Loss of nitrogen... ... 79
5.5.2 Loss of phosphorus... ... 81
5.5.3 Loss of Potassium... ... 83
Chapter VI Conclusions and Recommendations... 86
6.1 Conclusions... ... 86
6.2 Recommendations... ... 87
References... ... 88
Appendices... ... 94
Curriculum Vitae... ... 102
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List of Tables
Page
Table 3-1 Distribution of the land in the PARC area... 32
Table 3-2 Types of land use in the PARC area... 37
Table 3-3 Population density and land allocation in the PARC area... 39
Table 3-4 Area, yield and productivity of main crops in PARC in 1995... 42
Table 5-1 The potential soil loss estimated by USLE... 60
Table 5-2 The potential soil loss and its proportion estimated by SLEMSA... 68
Table 5-3 The potential soil loss and its proportion estimated by MMF... 72
Table 5-4 Comparison between measured and estimated values by USLE... 75
Table 5-5 Comparison between measured and estimated values by SLEMSA.. 76
Table 5-6 Comparison between measured and estimated values by MMF... 78
Table 5-7 The estimated potential soil loss and loss of nitrogen in SMUs... 80
Table 5-8 The cost of the loss of nitrogen in SMUs... 81
Table 5-9 The estimated potential soil loss and loss of potassium in SMUs... 82
Table 5-10 The cost of the loss of phosphorus in SMUs... 83
Table 5-11 The estimated potential soil loss and loss of phosphorus in SMUs... 84
Table 5-12 The cost of the loss of potassium in SMUs... 85
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List of Figures
Page
Figure 2-1 The estimation of cost of soil erosion... 28
Figure 3-1 The geographical location of the study area... 32
Figure 3-2 The elevation map in the study area... 33
Figure 3-3 The slope map in the study area... ... 35
Figure 3-4 The map of the land use in the study area... 36
Figure 3-5 The map of the soil types in the study area... 38
Figure 3-6 The dynamics of the rainfall in the study area... 40
Figure 3-7 The direction of the surface flow in the study area... 41
Figure 4-1 The steps of the soil loss estimation and its extra cost... 44
Figure 4-2 A cartographic model for estimating LS factor... 46
Figure 4-3 A cartographic model of the Universal Soil Loss Equation... 48
Figure 4-4 A cartographic model of SLEMSA... 50
Figure 4-5 A cartographic model of Morgan, Morgan and Finney model... 52
Figure 4-6 Steps in the estimation of cost of NPK in soil mapping units... 55
Figure 5-1 The soil erodibility index... ... 57
Figure 5-2 The topographic factor... ... 58
Figure 5-3 The crop management factor... ... 59
Figure 5-4 The spatial distribution of soil loss estimated by USLE... 61
Figure 5-5 The K factor... ... 63
Figure5-6 The topographic factor... ... 64
Figure5-7 The crop management factor... ... 65
Figure5-8 The spatial distribution of soil loss estimated by SLEMSA... 67
Figure5-9 The soil detachment index (K) ... ... 69
Figure 5-10 The parameter of rainfall interception and steam flow... 71
Figure 5-11 The spatial distribution of soil loss estimated by MMF model.... 73
