Soil Water Erosion and Its Hydrodynamic Characteristics in Degraded Bald Patches of Alpine Meadows in the Yellow River Source Area, Western China
Abstract
:1. Introduction
2. Materials and Methods
2.1. Study Area
2.2. Experimental Design and Methods
2.3. Data Testing and Analysis
3. Results
3.1. Soil Water Erosion Patterns in Different Degraded Bald Patches
3.1.1. Soil Loss Status of Different Degraded Bald Patches
3.1.2. Soil Erosion Processes on Different Degraded Bald Patches
3.1.3. Surface Runoff Characteristics of Different Degraded Bald Patches
3.1.4. Relationship between Soil Erosion and the Degree of Meadow Degradation
3.2. Hydrodynamic Characteristics of Different Degraded Bald Patches
3.2.1. Flow Regime
3.2.2. Runoff Resistance
3.2.3. Runoff Shear Stress
3.3. Relationship between Soil Erosion and Hydrodynamic Characteristics of Bald Patches with Different Degrees of Degradation
3.3.1. Regression Equation of the Soil Erosion Rate and Hydrodynamic Parameters
3.3.2. Correlation Analysis of Soil Erosion Rate and Hydrodynamic Parameters
4. Discussion
4.1. Comparison with Existing Similar Studies
4.2. Effect of Vegetation Coverage and Slope on Hydrodynamic Characteristics
4.3. Implications of This Study for Sustainable Management of Meadow Ecosystems
5. Conclusions
- Vegetation coverage and slope are significant factors affecting soil erosion in degraded bald patches, and soil erosion and runoff rates increase exponentially as a result of meadow degradation (p < 0.01). Rodent activity can increase soil erosion compared to vegetated slopes;
- All slope flows are laminar, with Reynolds and Froude numbers decreasing exponentially and linearly, respectively, as a function of vegetation coverage (p < 0.01), both of which are positively correlated with slope gradients. The Darcy–Weisbach resistance and Manning roughness coefficients were found to be larger on densely vegetated and gently sloping surfaces and significantly affected by vegetation coverage and slope; (p < 0.05). Runoff shear stress is positively correlated with vegetation coverage and slope, with a greater effect on the slope than vegetation coverage (p < 0.05);
- The relationship between soil erosion rate and flow velocity, Reynolds number, Froude number, and runoff shear stress can be described by power, logarithmic, exponential and linear functions, respectively (p < 0.01). Based on the Pearson correlation and grey correlation analysis results, we tentatively determined that the Reynolds number is the most suitable hydrodynamic parameter to describe the soil erosion process.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Degraded Meadow Types | Moisture Content | Density | Porosity | Firmness | Cohesion | Less Than a Certain Soil Particle Size (%) | ||
---|---|---|---|---|---|---|---|---|
(%) | (g m−3) | (%) | (kPa) | (kPa) | d < 2 mm | d < 0.5 mm | d < 0.075 mm | |
Degraded bald patches | 15.16 ± 2.08 | 1.51 ± 0.15 | 11.38 ± 0.14 | 25.6 ± 2.38 | 26.61 ± 3.24 | 75.26 | 48.97 | 8.15 |
Zokor mound bare ground | 9.35 ± 1.75 | 1.43 ± 0.11 | 14.34 ± 0.16 | 10.21 ± 2.15 | 12.56 ± 1.12 | 88.79 | 59.72 | 8.88 |
Slope (°) | Vegetation Coverage (%) | Flow Velocity (v, cm s−1) | Runoff Depth (h, mm) | Reynolds Number (Re) | Froude Number (Fr) | Darcy–Weisbach Resistance (f) | Manning Roughness (n) | Flow Shear Stress (τ, N m−2) |
---|---|---|---|---|---|---|---|---|
10° | 0 | 4.42 ± 0.17 Ca | 1.85 ± 0.21 Ade | 87.29 ± 29.83 BCa | 0.315 ± 0.060 Ca | 25.27 ± 6.58 Ae | 0.211 ± 0.046 Ade | 1.71 ± 1.07 Cf |
10% | 3.79 ± 0.20 Cb | 1.72 ± 0.12 Ae | 71.82 ± 24.27 Cb | 0.286 ± 0.054 Cb | 29.52 ± 8.28 Ae | 0.196 ± 0.039 Ae | 2.32 ± 0.98 Ce | |
30% | 3.38 ± 0.22 Cc | 1.94 ± 0.22 Ad | 59.23 ± 22.60 Cc | 0.277 ± 0.053 Cbc | 44.78 ± 13.95 Ac | 0.233 ± 0.056 Ad | 2.67 ± 0.99 Cd | |
50% | 2.93 ± 0.18 Cd | 2.38 ± 0.23 Ac | 50.01 ± 19.80 Cd | 0.237 ± 0.050 Cd | 36.24 ± 11.09 Ad | 0.258 ± 0.063 Ac | 3.56 ± 1.04 Cc | |
70% | 2.38 ± 0.22 Ce | 2.85 ± 0.31 Ab | 40.96 ± 17.48 Ce | 0.195 ± 0.040 Ce | 56.77 ± 17.44 Ab | 0.292 ± 0.071 Ab | 3.92 ± 1.05 Cab | |
90% | 2.31 ± 0.20 BCf | 3.38 ± 0.25 Aa | 37.70 ± 16.53 Ce | 0.161 ± 0.032 BCf | 77.43 ± 26.35 Aa | 0.337 ± 0.090 Aa | 4.05 ± 1.11 Ca | |
20° | 0 | 4.89 ± 0.24 Ba | 1.68 ± 0.15 Be | 93.73 ± 32.78 Ba | 0.366 ± 0.078 Ba | 23.25 ± 5.40 ABde | 0.187 ± 0.038 Be | 2.34 ± 2.07 Bf |
10% | 4.48 ± 0.28 Bb | 1.62 ± 0.17 Ade | 80.60 ± 29.50 Bb | 0.353 ± 0.063 Bab | 22.17 ± 5.90 Be | 0.188 ± 0.034 ABe | 2.98 ± 1.82 Be | |
30% | 3.97 ± 0.25 Bc | 1.80 ± 0.19 ABd | 68.53 ± 26.11 Bc | 0.321 ± 0.065 Bc | 28.72 ± 7.61 Bd | 0.208 ± 0.043 Bd | 3.42 ± 1.95 Bd | |
50% | 3.39 ± 0.24 Bd | 1.94 ± 0.18 Bc | 59.35 ± 24.57 Bd | 0.279 ± 0.060 Bd | 39.32 ± 10.49 ABc | 0.239 ± 0.051 Bc | 4.08 ± 1.96 Bc | |
70% | 2.85 ± 0.24 Be | 2.38 ± 0.24 Bb | 51.78 ± 20.33 Bde | 0.228 ± 0.054 Be | 51.08 ± 17.17 ABb | 0.297 ± 0.068 Ab | 4.48 ± 2.23 Bb | |
90% | 2.32 ± 0.28 Bf | 2.71 ± 0.12 Ba | 46.63 ± 19.93 ABef | 0.181 ± 0.040 Bf | 63.05 ± 25.36 Ba | 0.313 ± 0.080 Ba | 4.74 ± 2.23 Ba | |
30° | 0 | 5.21 ± 0.24 Aa | 1.58 ± 0.10 Bd | 114.89 ± 34.60 Aa | 0.413 ± 0.084 Aa | 20.81 ± 3.70 Bcd | 0.171 ± 0.029 BCd | 2.61 ± 2.73 Af |
10% | 4.81 ± 0.23 Ab | 1.47 ± 0.18 ABd | 90.80 ± 30.06 Ab | 0.385 ± 0.087 Ab | 18.97 ± 4.3 BCd | 0.156 ± 0.031 Ce | 3.24 ± 2.92 Ae | |
30% | 4.31 ± 0.23 Ac | 1.64 ± 0.15 Bcd | 79.36 ± 29.42 Ac | 0.352 ± 0.091 Ac | 21.02 ± 5.28 Ccd | 0.168 ± 0.035 Cde | 3.77 ± 3.16 Ad | |
50% | 3.85 ± 0.23 Ad | 1.77 ± 0.14 Cc | 71.16 ± 27.35 Acd | 0.317 ± 0.081 Ad | 26.86 ± 7.64 Cc | 0.201 ± 0.044 Cc | 4.34 ± 3.19 Ac | |
70% | 3.53 ± 0.25 Ae | 1.98 ± 0.20 Cb | 64.84 ± 23.96 Ad | 0.281 ± 0.073 Ae | 39.74 ± 11.11 Cb | 0.243 ± 0.052 Bb | 4.68 ± 3.33 Ab | |
90% | 2.77 ± 0.21 Af | 2.38 ± 0.26 Ca | 53.69 ± 31.78 Ae | 0.244 ± 0.068 Af | 54.05 ± 15.48 Ca | 0.296 ± 0.063 Ca | 5.27 ± 3.45 Aa |
Hydrodynamic Parameters | Vegetation Coverage (%) | ||
---|---|---|---|
10° | 20° | 30° | |
Flow velocity (v, m s−1) | y = 4.2189e−0.007x (R2 = 0.9726) | y = 4.9502e−0.008x (R2 = 0.9938) | y = 5.2721e−0.007x (R2 = 0.9833) |
Reynolds number(Re) | y = 81.165e−0.009x (R2 = 0.9709) | y = 88.789e−0.008x (R2 = 0.9778) | y = 104.66e−0.007x (R2 = 0.9278) |
Froude number(Fr) | y = −0.0017x + 0.3146 (R2 = 0.9796) | y = −0.0018x + 0.4081 (R2 = 0.9976) | y = −0.0021x + 0.3746 (R2 = 0.9900) |
Darcy–Weisbach resistance coefficient(n) | y = 26.143e0.0113x (R2 = 0.9021) | y = 21.158e0.0122x (R2 = 0.9911) | y = 17.387e0.0114x (R2 = 0.9396) |
Manning roughness coefficient(n) | y = 0.1972e0.0057x (R2 = 0.9695) | y = 0.1742e0.0077x (R2 = 0.9608) | y = 0.1514e0.0067x (R2 = 0.9236) |
Runoff shear stress(τ, N m−2) | y = 0.0264x + 1.9382 (R2 = 0.9447) | y = 0.026x + 2.5893 (R2 = 0.9628) | y = 0.0276x + 2.8333 (R2 = 0.9781) |
Slope(°) | SD | VC | RR | v | h | Re | Fr | f | n | τ |
---|---|---|---|---|---|---|---|---|---|---|
10° | Grey correlation | 0.497 | 0.776 | 0.812 | 0.615 | 0.844 | 0.796 | 0.640 | 0.638 | 0.599 |
Pearson correlation | −0.998 ** | 0.993 ** | 0.994 ** | −0.914 * | 0.993 ** | 0.971 ** | −0.895 * | −0.931 ** | −0.987 ** | |
Sig.(2-tailed) | 0 | 0 | 0 | 0.011 | 0 | 0.001 | 0.016 | 0.007 | 0 | |
20° | Grey correlation | 0.508 | 0.830 | 0.848 | 0.658 | 0.842 | 0.84 | 0.590 | 0.638 | 0.636 |
Pearson correlation | −0.989 ** | 0.997 ** | 0.994 ** | −0.916 * | 0.993 ** | 0.974 ** | −0.946 ** | −0.917 * | −0.996 ** | |
Sig.(2-tailed) | 0 | 0 | 0 | 0.01 | 0 | 0.001 | 0.004 | 0.01 | 0 | |
30° | Grey correlation | 0.509 | 0.819 | 0.828 | 0.673 | 0.845 | 0.816 | 0.612 | 0.646 | 0.647 |
Pearson correlation | −0.994 ** | 0.998 ** | 0.992 ** | −0.910 * | 0.974 ** | 0.998 ** | −0.901 * | −0.905 * | −0.997 ** | |
Sig.(2-tailed) | 0 | 0 | 0 | 0.012 | 0.001 | 0 | 0.014 | 0.013 | 0 |
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Tong, S.; Li, G.; Li, X.; Li, J.; Zhai, H.; Zhao, J.; Zhu, H.; Liu, Y.; Chen, W.; Hu, X. Soil Water Erosion and Its Hydrodynamic Characteristics in Degraded Bald Patches of Alpine Meadows in the Yellow River Source Area, Western China. Sustainability 2023, 15, 8165. https://doi.org/10.3390/su15108165
Tong S, Li G, Li X, Li J, Zhai H, Zhao J, Zhu H, Liu Y, Chen W, Hu X. Soil Water Erosion and Its Hydrodynamic Characteristics in Degraded Bald Patches of Alpine Meadows in the Yellow River Source Area, Western China. Sustainability. 2023; 15(10):8165. https://doi.org/10.3390/su15108165
Chicago/Turabian StyleTong, Shengchun, Guorong Li, Xilai Li, Jinfang Li, Hui Zhai, Jianyun Zhao, Haili Zhu, Yabin Liu, Wenting Chen, and Xiasong Hu. 2023. "Soil Water Erosion and Its Hydrodynamic Characteristics in Degraded Bald Patches of Alpine Meadows in the Yellow River Source Area, Western China" Sustainability 15, no. 10: 8165. https://doi.org/10.3390/su15108165