Journal of Geographical Sciences >
Spatio-temporal characteristics of soil protection efforts of the Grain for Green Project in northern Shaanxi Province
Liu Wenchao (1986–), PhD and Lecturer, specialized in remote sensing of natural resources and environment, land use and cover change (LUCC) and ecological effect. E-mail: dorayliu@163.com |
Received date: 2019-04-16
Accepted date: 2019-06-22
Online published: 2020-05-25
Supported by
National Key Research and Development Program of China(No.2016YFC0500204)
Doctor Foundation of Tianjin Normal University(No.52XB1622)
Copyright
This paper looks at the Green for Grain Project in northern Shaanxi Province. Based on remote sensing monitoring data, this study analyzes the locations of arable land in northern Shaanxi in the years 2000, 2010 and 2013 as well as spatio-temporal changes over that period, and then incorporates data on the distribution of terraced fields to improve the input parameters of a RUSLE model and simulate and generate raster data on soil erosion for northern Shaanxi at different stages with a accuracy verification. Finally, combined with the dataset of farmland change, compared and analyzed the characteristics of soil erosion change in the converted farmland to forest (grassland) and the unconverted farmland in northern Shaanxi, so as to determine the project’s impact on soil erosion over time across the region. The results show that between 2000 and 2010, the soil erosion modulus of repurposed farmland in northern Shaanxi decreased 22.7 t/ha, equivalent to 47.08% of the soil erosion modulus of repurposed farmland in 2000. In the same period, the soil erosion modulus of non-repurposed farmland fell 10.99 t/ha, equivalent to 28.6% of the soil erosion modulus of non-repurposed farmland in 2000. The soil erosion modulus for all types of land in northern Shaanxi decreased by an average of 14.51 t/ha between 2000 and 2010, equivalent to 41.87% of the soil erosion modulus for the entire region in 2000. This suggests that the Green for Grain Project effectively reduced the soil erosion modulus, thus helping to protect the soil. In particular, arable land that was turned into forest and grassland reduced erosion most noticeably and contributed most to soil conservation. Nevertheless, in the period 2010 to 2013, which was a period of consolidation of the Green for Grain Project, the soil erosion modulus and change in volume of soil erosion in northern Shaanxi were significantly lower than in the previous decade.
LIU Wenchao , LIU Jiyuan , KUANG Wenhui . Spatio-temporal characteristics of soil protection efforts of the Grain for Green Project in northern Shaanxi Province[J]. Journal of Geographical Sciences, 2020 , 30(3) : 401 -422 . DOI: 10.1007/s11442-020-1734-7
Figure 1 Location and topography of the Loess Plateau, northern Shaanxi |
Figure 2 Terracing identification process |
Figure 3 Relationship between the area of terrace walls and fields |
Figure 4 Interpreted terraced field data (a) and 1 km×1 km grid showing percentage of terraced fields (b) in the Loess Plateau, northern Shaanxi |
Table 1 National soil erosion classification system |
Primary | Secondary | Intensity |
---|---|---|
1 Water erosion | 11 Surface erosion | 111Trace 112 Slight 113 Moderate |
114 High 115 Severe 116 Extreme | ||
12 Gullying | 121Trace 122 Slight 123 Moderate | |
124 High 125 Severe 126 Extreme | ||
2 Wind erosion | 20 No sub-classes | 201Trace 202 Slight 203 Moderate |
204 High 205 Severe 206 Extreme | ||
3 Freeze-thaw erosion | 30 No sub-classes | 301Trace 302 Slight 303 Moderate |
304 High | ||
4 Gravitational erosion | 40 No sub-classes | No intensity grading |
5 Man-made erosion | 50 No sub-classes | No intensity grading |
Table 2 Soil erosion classification standards |
Level | Average erosion modulus (t/ha·a) |
---|---|
1 Trace erosion | < 10 |
2 Slight erosion | 10-25 |
3 Moderate erosion | 25-50 |
4 High erosion | 50-80 |
5 Severe erosion | 80-150 |
6 Extreme erosion | ≥ 150 |
Figure 5 Spatial distribution of erosion verification points in the Loess Plateau, northern Shaanxi |
Table 3 RUSLE model simulation results |
Erosion level | Theoretical value (t/ha) | Verification points | No. of points with simulated values within the theoretical value range | Correct judgement rate (%) | 2005 model simulated average (t/ha) |
---|---|---|---|---|---|
Trace | <10 | 50 | 38 | 76.00 | 7.89 |
Slight | 10-25 | 46 | 33 | 71.74 | 17.90 |
Moderate | 25-50 | 56 | 39 | 69.64 | 37.29 |
High | 50-80 | 46 | 28 | 60.87 | 61.61 |
Severe | 80-150 | 50 | 37 | 74.00 | 89.43 |
Extreme | ≥ 150 | 73 | 38 | 52.05 | 123.42 |
Figure 6 Location of the hydrological stations and sediment runoff moduli in northern Shaanxi |
Table 4 Hydrological station data |
Station name | Catchment area (104 ha) | Sediment runoff (108 t) | Sediment runoff modulus (t/ha) |
---|---|---|---|
Wenjiachuan | 86.45 | 0.11 | 12.72 |
Baijiachaun | 296.62 | 0.96 | 32.36 |
Ganguyi | 58.91 | 0.22 | 37.35 |
Huangfuchuan | 31.99 | 0.14 | 43.76 |
Zhuangtou | 251.54 | 0.70 | 27.83 |
Longmen | 4975.52 | 2.36 | 4.75 |
Table 5 Statistical analysis of soil erosion in Yan’an and Yulin in 2000, 2010 and 2013 |
2000 | 2010 | 2013 | ||||
---|---|---|---|---|---|---|
Soil erosion (104 t) | Proportion* (%) | Soil erosion (104 t) | Proportion* (%) | Soil erosion (104 t) | Proportion* (%) | |
Yan’an | 11856.38 | 43.13 | 6484.56 | 40.59 | 5503.15 | 35.46 |
Yulin | 15631.69 | 56.87 | 9493.14 | 59.41 | 10016.61 | 64.54 |
* Ratio of soil erosion before to soil erosion after the change of land use |
Figure 7 Soil erosion moduli for northern Shaanxi in 2000, 2010 and 2013 |
Table 6 Soil erosion moduli change of repurposed farmland in northern Shaanxi between 2000 and 2010 |
Type of change | Region | Yan’an | Yulin | |||
---|---|---|---|---|---|---|
Soil erosion (104 t) | Proportion* (%) | Soil erosion (104 t) | Proportion* (%) | Soil erosion (104 t) | Proportion* (%) | |
Farmland→Forest | -217.11 | -43.91 | -129.05 | -43.18 | -88.06 | -45.02 |
Farmland→Grassland | -654.29 | -48.51 | -391.28 | -47.93 | -263.01 | -49.39 |
Farmland→Water body | -0.26 | -24.49 | -0.10 | -33.99 | -0.16 | -20.94 |
Farmland→Construction | -13.84 | -38.31 | -7.57 | -43.10 | -6.28 | -33.79 |
Farmland→Unutilized | -0.40 | -28.14 | -0.19 | -25.72 | -0.21 | -30.75 |
Total reductions | -885.90 | -47.08 | -528.18 | -46.59 | -357.71 | -47.82 |
* Ratio of soil erosion before to soil erosion after the change of land use |
Figure 8 Change in soil erosion moduli of repurposed farmland in northern Shaanxi between 2000 and 2010 (a) and between 2010 and 2013 (b) |
Table 7 Changes in soil erosion resulting from repurposing farmland in northern Shaanxi between 2010 and 2013 |
Type of change | Region | Yan’an | Yulin | |||
---|---|---|---|---|---|---|
Soil erosion (t) | Proportion* (%) | Soil erosion (t) | Proportion* (%) | Soil erosion (t) | Proportion* (%) | |
Farmland→Forest | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
Farmland→Grassland | -45.50 | -51.98 | 0.00 | 0.00 | -45.50 | -51.98 |
Farmland→Water body | -295.72 | -7.24 | -44.67 | -4.67 | -251.05 | -8.02 |
Farmland→Construction | -2162.13 | -15.32 | 130.87 | 3.05 | -2293.00 | -23.35 |
Farmland→Unutilized | 1880.37 | 10.26 | -193.36 | -43.39 | 2073.73 | 11.59 |
Total reductions | -622.97 | -1.70 | -107.17 | -1.88 | -515.81 | -1.67 |
* Ratio of soil erosion before to soil erosion after the change of land use |
Figure 9 Change in soil erosion moduli in northern Shaanxi between 2000 and 2010 (a) and between 2010 and 2013 (b) |
Figure 10 Variation of vegetation cover fraction (a) and mean precipitation (b) in northern Shaanxi between 2000 and 2013 |
Figure 11 Comparison of variation of mean annual precipitation and vegetation cover fraction in northern Shaanxi from 2000 to 2010 (a, b) and from 2010 to 2013 (c, d) |
Table 8 Changes in the soil erosion moduli of different regions of northern Shaanxi between 2000 and 2010 |
2000 mean soil erosion modulus (t/ha) | 2010 mean soil erosion modulus (t/ha) | 2000-2010 change in soil erosion modulus (%) | |
---|---|---|---|
Repurposed farmland | 48.22 | 25.52 | -47.08 |
Non-repurposed farmland | 38.41 | 27.43 | -28.60 |
Whole of northern Shaanxi | 34.66 | 20.15 | -41.87 |
Table 9 Changing soil erosion moduli of terraced and sloping farmland in northern Shaanxi between 2000 and 2010 |
2000 mean soil erosion modulus (t/ha) | 2010 mean soil erosion modulus (t/ha) | 2000-2010 change in soil erosion modulus (%) | |
---|---|---|---|
Repurposed terraced farmland | 15.21 | 14.58 | -4.17 |
Repurposed sloping farmland | 50.66 | 26.30 | -48.09 |
Non-repurposed terraced farmland | 16.74 | 15.84 | -5.38 |
Non-repurposed sloping farmland | 41.57 | 29.12 | -29.95 |
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