xi
Contents
1 Introduction and Background of Rainfall Erosivity Processes
and Soil Erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Rainfall Erosivity Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Impacts of Climate Change on Rainfall Erosivity . . . . . . . . . . . . . . . . 2
1.3 Soil Erosion Processes and Models . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Natural Conditions in Central Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 Topography and Climatic Conditions in Central Asia . . . . . . . . . . . . . 9
2.2 Description of Central Asian Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3 Data Sources and Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1 Projected and Observed Rainfall Data . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2 RUSLE Model and Its Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2.1 Rainfall–Runoff Erosivity (R) Factor . . . . . . . . . . . . . . . . . . 19
3.2.2 Soil Erodibility Factor (K) . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2.3 Slope Length and Steepness (LS) Factor . . . . . . . . . . . . . . . . 21
3.2.4 Cover Management (C) Factor . . . . . . . . . . . . . . . . . . . . . . . 23
3.2.5 Conservation Practice (P) Factor . . . . . . . . . . . . . . . . . . . . . . 24
3.3 Annual Erosivity Density Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.4 Trend Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.5 Model Evaluation Rainfall Erosivity . . . . . . . . . . . . . . . . . . . . . . . . . 25
4 Projected Rainfall Erosivity and Soil Erosion in Central Asia . . . . . . . 27
4.1 RUSLE Model Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.2 Current Rate of Soil Erosion in Central Asia . . . . . . . . . . . . . . . . . . . 30
4.3 Rainfall Erosivity Analysis Under Baseline and Projected
Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.4 Annual Erosivity Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.5 Projected Future Soil Erosion Potential in Central Asia . . . . . . . . . . 35
4.6 Rainfall Erosivity and Soil Erosion at the National Level . . . . . . . . . 38
Contents
1 Introduction and Background of Rainfall Erosivity Processes
and Soil Erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Rainfall Erosivity Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Impacts of Climate Change on Rainfall Erosivity . . . . . . . . . . . . . . . . 2
1.3 Soil Erosion Processes and Models . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Natural Conditions in Central Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 Topography and Climatic Conditions in Central Asia . . . . . . . . . . . . . 9
2.2 Description of Central Asian Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3 Data Sources and Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1 Projected and Observed Rainfall Data . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2 RUSLE Model and Its Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2.1 Rainfall–Runoff Erosivity (R) Factor . . . . . . . . . . . . . . . . . . 19
3.2.2 Soil Erodibility Factor (K) . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2.3 Slope Length and Steepness (LS) Factor . . . . . . . . . . . . . . . . 21
3.2.4 Cover Management (C) Factor . . . . . . . . . . . . . . . . . . . . . . . 23
3.2.5 Conservation Practice (P) Factor . . . . . . . . . . . . . . . . . . . . . . 24
3.3 Annual Erosivity Density Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.4 Trend Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.5 Model Evaluation Rainfall Erosivity . . . . . . . . . . . . . . . . . . . . . . . . . 25
4 Projected Rainfall Erosivity and Soil Erosion in Central Asia . . . . . . . 27
4.1 RUSLE Model Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.2 Current Rate of Soil Erosion in Central Asia . . . . . . . . . . . . . . . . . . . 30
4.3 Rainfall Erosivity Analysis Under Baseline and Projected
Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.4 Annual Erosivity Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.5 Projected Future Soil Erosion Potential in Central Asia . . . . . . . . . . 35
4.6 Rainfall Erosivity and Soil Erosion at the National Level . . . . . . . . . 38