scholarly journals Inhibiting Effects of Vegetation on the Characteristics of Runoff and Sediment Yield on Riparian Slope along the Lower Yellow River

2019 ◽  
Vol 11 (13) ◽  
pp. 3685 ◽  
Author(s):  
Yifan Zhang ◽  
Qinghe Zhao ◽  
Zihao Cao ◽  
Shengyan Ding
Keyword(s):  
Sediment Yield ◽  
Riparian Vegetation ◽  
Yellow River ◽  
Vegetation Coverage ◽  
Hydraulic Characteristics ◽  
Slope Gradient ◽  
The Lower Yellow River ◽  
Inhibiting Effect ◽  
Slope Sediment ◽  
Runoff And Sediment Yield

Riparian vegetation plays a vital role in soil and water conservation and river health maintenance. However, its inhibiting effects on water and soil loss are limited by different factors, such as slope gradient, vegetation coverage and their interaction. Therefore, this study quantified the inhibiting effect of riparian vegetation on the runoff, sediment and hydraulic characteristics of overland flow, and assessed its relative contribution to slope gradient. Specifically, we selected a riparian slope along the lower Yellow River as a case, and used a field-simulated rainfall experiment under specific rainfall intensity (90 mm/h), different vegetation coverage (0%, 15% and 30%) and slope gradients (5°, 10°, 15° and 20°). The results showed that the presence of vegetation can reduce the slope runoff rate and erosion rate. However, greater slope gradients can result in a lowering of the inhibiting effects of riparian vegetation on sediment yield. There was a critical value of vegetation coverage for inhibiting eroded sediments which was influenced by the degree of slope gradient. At 15% vegetation coverage, vegetation inhibited the slope sediment yield greatly at a slope gradient of less than 8°; while at 30% vegetation coverage, vegetation greatly inhibited the slope sediment yield at slope gradients <11°. Hydraulic characteristics were closely related to the slope gradient and vegetation coverage by the power function. Grey correlation analysis revealed that, with increasing of vegetation coverage, the effect of stream power on slope sediment yield decreased, while the effect of the friction coefficient on slope sediment yield increased. In summary, riparian vegetation can effectively inhibit slope runoff and sediment yield, but its inhibiting effect is notably affected by slope gradient.

scholarly journals The relative contributions of slope gradient and vegetation cover on erosion characteristics of riparian slopes along the lower Yellow River, China

2021 ◽  
Author(s):  
Zihao Cao ◽  
Qinghe Zhao ◽  
Shengyan Ding ◽  
Yifan Zhang
Keyword(s):  
Particle Size ◽  
Soil Erosion ◽  
Sediment Yield ◽  
Vegetation Cover ◽  
Yellow River ◽  
Size Composition ◽  
Steep Slope ◽  
Slope Gradient ◽  
Lower Yellow River ◽  
The Lower Yellow River

Slope gradient and vegetation cover play key roles in soil erosion process. Exploring the effects of slope gradient and vegetation cover on runoff and sediment yielding characteristics is therefore of great importance for minimizing soil erosion. In this work, based on field scouring experiments on the riparian slopes of the lower Yellow River, China, variation in total runoff, accumulative runoff sediment concentration, erosion sediment yield, and sediment particle size composition under four slope gradients (5°, 10°, 15°, 20°) and three vegetation cover levels (0%, 15%, 30%) were analyzed. Runoff and sediment yield were greatly influenced by slope gradient at steep slope gradients (15° and 20°), while they were mainly affected by vegetation cover at medium slope gradients (5° and 10°). The main enriched particle size of the eroded sediment showed a trend of first increasing and then decreasing with the increasing slope gradient. There was an interaction between slope gradient and vegetation cover, the effect of vegetation cover on erosion sediment yield weakened gradually with increasing slope gradient (at medium slope gradients of 5° and 10°), while the effect of slope gradient increased at steep slope gradients (15° and 20°).

Soil Erosion Process in Sloped Shrub Plots under Simulated Rainfall

2011 ◽  
Vol 347-353 ◽  
pp. 2094-2097 ◽  
Author(s):  
Pei Qing Xiao ◽  
Wen Yi Yao ◽  
Chang Gao Wang
Keyword(s):  
Soil Erosion ◽  
Sediment Yield ◽  
Rainfall Intensity ◽  
Infiltration Rate ◽  
Simulated Rainfall ◽  
Slope Gradient ◽  
Erosion Process ◽  
Infiltration Process ◽  
Negative Relation ◽  
Runoff And Sediment Yield

Runoff, sediment yield and infiltration process of shrub plots were studied under rainfall intensities of 45, 87 and 127 mm/h with 20° slope gradient using simulated rainfall experiment. The results showed that cumulative runoff and cumulative sediment yield of shrub plot had an obvious positive correlation with rainfall time. Under rainfall intensity of 45 mm/h, runoff and sediment yield of shrub plot kept a constant level. Under rainfall intensity of 87 mm/h, runoff kept a fluctuant increase, whereas sediment yield basically kept steady. Under rainfall intensity of 127 mm/h, runoff and sediment yield of shrub plot increased evidently due to the formation of erosion pits. Infiltration rate of shrub plot had a negative relation with runoff as well as sediment yield.

Effect of Shrub Planting on Runoff and Sediment under Simulated Rainfall

2012 ◽  
Vol 212-213 ◽  
pp. 141-144
Author(s):  
Pei Qing Xiao ◽  
Wen Yi Yao ◽  
Chang Gao Wang
Keyword(s):  
Shear Stress ◽  
Sediment Yield ◽  
Simulated Rainfall ◽  
Slope Gradient ◽  
Flow Shear ◽  
Sediment Yields ◽  
Hydraulic Mechanism ◽  
Flow Shear Stress ◽  
Sediment Reduction ◽  
Runoff And Sediment Yield

Effect of shrub on runoff and sediment yield and its hydraulic mechanism of shrub were studied under rainfall intensities of 45, 87 and 127mm/h with 20°slope gradient using simulated rainfall experiment. the results showed that average runoff rates ranged from 39.7 to 126.0 L/min for bare plots and 0.77 to 4.83 L/min for shrub plots, and the runoff rates from shrub plots were much less than from bare plots. Average sediment yields varied from 3636.7 to 9436.3 g/min for bare plots and from 28.0 to 421.6 g/min for shrub plots. The critical flow shear stress of 1.65 N/m2 on shrub slope and 0.861 N/m2 on bare slope were got under experiment condition. The sediment yield increased with the increase of flow shear stress. The experiment results are meaningful for quantifying runoff and sediment reduction and deepening soil erosion mechanical process also.

Effects of rainfall intensity and slope gradient on runoff and sediment yield from hillslopes with weathered granite

2019 ◽  
Vol 26 (31) ◽  
pp. 32559-32573
Author(s):  
Longzhou Deng ◽  
Liping Zhang ◽  
Xiaojuan Fan ◽  
Tianyu Sun ◽  
Kai Fei ◽  
...  
Keyword(s):  
Sediment Yield ◽  
Rainfall Intensity ◽  
Slope Gradient ◽  
Weathered Granite ◽  
Runoff And Sediment Yield

scholarly journals Relationships between Riparian Vegetation Pattern and the Hydraulic Characteristics of Upslope Runoff

2019 ◽  
Vol 11 (10) ◽  
pp. 2966 ◽  
Author(s):  
Qinghe Zhao ◽  
Yifan Zhang ◽  
Shanshan Xu ◽  
Xiaoyu Ji ◽  
Shuoqian Wang ◽  
...  
Keyword(s):  
Shear Stress ◽  
Vegetation Cover ◽  
Riparian Vegetation ◽  
Flow Resistance ◽  
Overland Flow ◽  
Vegetation Pattern ◽  
Hydraulic Characteristics ◽  
Slope Gradient ◽  
Flow Shear ◽  
Flow Shear Stress

Riparian vegetation plays a vital role in inhibiting soil and water loss, but few studies have quantified the relationships between vegetation spatial pattern and the hydraulic characteristics of upslope runoff. This study investigated how hydraulic characteristics (e.g., runoff coefficient, flow regime, flow resistance, and flow shear stress of overland flow) responded to differences in vegetation cover (15% and 30%), slope gradient (5°, 10°, 15°, and 20°), and vegetation pattern in the riparian zone along the lower Yellow River, China, based on landscape pattern analysis and a runoff scouring experiment with flow rates of 9 and 15 L/min and an experimental plot size of 1 m × 3 m. We found that runoff generation on shallow slopes was moderated by increasing vegetation cover, but that this moderating effect decreased on steeper slopes. The regime of overland flow switched from laminar and subcritical on the 5° slope (Fr = 0.56–0.87) to laminar and critical on the 10°, 15°, and 20° slopes (Fr = 1.02–2.18). Flow resistance increased with vegetation cover and flow rate and decreased with slope gradients, and it was larger on shallow slopes with high vegetation cover. Flow shear stress had a range of 1.42–3.55 N m−2, and it increased with increasing slope gradient, vegetation cover, and flow rate. The hydraulic characteristics of upslope runoff, especially flow resistance, were significantly related to vegetation pattern at both the landscape and class levels. Flow resistance was negatively related to patch density, and positively related to perimeter–area fractal dimension and connectance index. The influencing mechanism of landscape patterns on soil erosion processes is dependent on the landscape scale, since the relationships between flow resistance and some landscape pattern indices (aggregation index, effective mesh size, and splitting index) were opposite at the landscape level compared to the class level. We conclude that fragmented vegetation distributions reduce flow resistance, and that riparian vegetation could be managed to inhibit slope erosion by increasing flow resistance.

scholarly journals Effects of Slope Gradient on Runoff and Sediment Yield on Machine-Induced Compacted Soil in Temperate Forests

Forests ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 49
Author(s):  
Meghdad Jourgholami ◽  
Sara Karami ◽  
Farzam Tavankar ◽  
Angela Lo Monaco ◽  
Rodolfo Picchio
Keyword(s):  
Critical Point ◽  
Sediment Yield ◽  
Surface Runoff ◽  
Soil Loss ◽  
Temperate Forests ◽  
Runoff Coefficient ◽  
Slope Gradient ◽  
Runoff And Soil Loss ◽  
Runoff And Sediment Yield ◽  
Runoff Plot

There has been a severely negative impact on soil water resources in temperate forests caused by the introduction of the type of heavy machinery in the forestry sector used for forest harvesting operations. These soil disturbances increase the raindrop impact on bare mineral soil, decrease infiltration rate, detach soil particles, and enhance surface flow. According to several studies, the role of slope gradient influence on runoff and soil loss continues to be an issue, and therefore more study is needed in both laboratory simulations and field experiments. It is important to define and understand what the impacts of slope gradient in harvesting practices are, so as to develop guidelines for forest managers. More knowledge on the key factors that cause surface runoff and soil loss is important in order to limit any negative results from timber harvesting operations performed on hilly terrains in mountainous forests. A field setting using a runoff plot 2 m2 in size was installed to individualize the effects of different levels of slope gradient (i.e., 5, 10, 15, 20, 25, 30, 35, and 40%) on the surface runoff, runoff coefficient, and sediment yield on the skid trails under natural rainfall conditions. Runoff and sediment yield were measured with 46 rainfall events which occurred during the first year after machine traffic from 17 July 2015 to 11 July 2016 under natural conditions. According to Pearson correlation, runoff (r = 0.51), runoff coefficient (r = 0.55), and sediment yield (r = 0.51) were significantly correlated with slope gradient. Results show that runoff increased from 2.45 to 6.43 mm as slope gradient increased from 5 to 25%, reaching to the critical point of 25% for slope. Also, further increasing the slope gradient from 25 to 40% led to a gradual decrease of the runoff from 6.43 to 4.62 mm. Runoff coefficient was significantly higher under the plot with a slope gradient of 25% by 0.265, whereas runoff coefficient was lowest under the plot with a slope gradient of 5%. Results show that sediment yield increased by increasing the slope gradient of plot ranging 5% to 30%, reaching to the critical point of 30%, and then decreased as the slope gradient increased from 35% to 40%. Runoff plot with a slope gradient of 30% (4.08 g m−2) ≈ plot length of 25% (3.91 g m−2) had a significantly higher sediment yield, whereas sediment yield was lowest under the plot with a slope gradient of 5% and 10%. A regression analysis of rainfall and runoff showed that runoff responses to rainfall for plots with different slope gradients were linearly and significantly increased. According to the current results, log skidding operations should be planned in the skid trails with a slope gradient lower than the 25 to 30% to suppress the negative effect of skidding operations on runoff and sediment yield.

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