scholarly journals Investigating rainfall duration effects on transport of chemicals from soil to surface runoff on a loess slope under artificial rainfall conditions

2019 ◽  
Vol 14 (No. 4) ◽  
pp. 183-194
Author(s):  
Yali Zhang ◽  
Xiaoyang Li ◽  
Xingchang Zhang ◽  
Huaien Li
Keyword(s):  
Soil Erosion ◽  
Power Function ◽  
Surface Runoff ◽  
Concentration Curve ◽  
Desorption Kinetics ◽  
Concentration Change ◽  
Rainfall Duration ◽  
Loess Slope ◽  
Artificial Rainfall ◽  
Sheet Erosion

The release and transport of soil chemicals in water erosion conditions are important for the local environment, soil and water resources conservation. According to the artificial rainfall experiments with a constant rainfall intensity of 90 mm/h and different rainfall duration (30, 60, 90, 120 and 150 min), the traits of soil PO<sub>4</sub><sup>3–</sup>, K<sup>+</sup>, and Br<sup>–</sup> release and transport from soil to surface runoff on the loess slope were analysed, and a model describing the chemical concentration change in surface runoff under soil erosion conditions was developed. The runoff coefficient quickly increased in 15 min or so, and then it was stable in the range of 0.60–0.85. The sediment intensity decreased in 30 min and soon increased after severe sheet erosion occurred on the slope. The concentration curve of Br<sup>–</sup> in surface runoff can be divided into two stages, quickly decreasing in the initial 30 min after the surface runoff occurred, and then stable. The concentration curve of PO<sub>4</sub><sup>3–</sup> and K<sup>+</sup> in surface runoff can be divided into three stages, quickly decreasing like Br<sup>– </sup>was decreasing, then stable, and increasing after severe sheet erosion began. Compared with the exponential function, the power function was found more suitable for fitting the change in chemicals in runoff with unsaturated soil; while neither of them could well fit the PO<sub>4</sub><sup>3–</sup> and K<sup>+</sup> concentration change after severe erosion occurred. The transport of chemicals under complex soil erosion conditions seems to be a dynamic release process between surface runoff and sediment. Based on the convection-dispersion mechanism and desorption kinetics, the polynomial model under soil erosion conditions was created. For adsorbed PO<sub>4</sub><sup>3–</sup> and K<sup>+</sup>, it is more suitable to simulate that process than the power function, while it is not so good for mobile Br<sup>–</sup>.  

Experimental study on dynamic mechanism of sheet erosion processes on steep grassland in the loess region of China

2021 ◽  
Author(s):  
Qi Guo ◽  
Zhanli Wang
Keyword(s):  
Shear Stress ◽  
Soil Erosion ◽  
Power Function ◽  
Erosion Rate ◽  
Dynamic Mechanism ◽  
Erosion Process ◽  
Stream Power ◽  
Study Results ◽  
Loess Region ◽  
Sheet Erosion

&lt;p&gt;Sheet erosion has been the major erosion process on steep grassland since the Grain-for-Green project was implemented in 1999 in the Loess Plateau with serious soil erosion, in China. Quantifying sheet erosion rate on steep grassland could improve soil erosion estimation on loess hillslopes and provide scientific support for effectively controlling soil erosion and rationally managing grassland. Simulated rainfall experiments were conducted on grassland plot with vegetation coverage of 40% under complete combination of rainfall intensities of 0.7, 1.0, 1.5, 2.0 and 2.5 mm min&lt;sup&gt;-1&lt;/sup&gt; and slope gradients of 7&amp;#176;, 10&amp;#176;, 15&amp;#176;, 20&amp;#176; and 25&amp;#176;. Results showed that sheet erosion rate (&lt;em&gt;SE&lt;/em&gt;), varying from 0.0048 to 0.0578 kg m&lt;sup&gt;-2&lt;/sup&gt; min&lt;sup&gt;-1&lt;/sup&gt;, was well described by binary power function equation (&lt;em&gt;SE&lt;/em&gt; = 0.0026 &lt;em&gt;I&lt;/em&gt;&lt;sup&gt;1.306&lt;/sup&gt;&lt;em&gt;S&lt;/em&gt;&lt;sup&gt;0.662&lt;/sup&gt;) containing rainfall intensity and slope gradient with &lt;em&gt;R&lt;sup&gt;2&lt;/sup&gt;&lt;/em&gt; = 0.940. The logarithmic equation of shear stress (&lt;em&gt;SE&lt;/em&gt; = 0.084 + Ln (&lt;em&gt;&amp;#964;&lt;/em&gt;)) and the power function equation of stream power (&lt;em&gt;SE&lt;/em&gt; = 1.141 &lt;em&gt;&amp;#631;&lt;/em&gt;&lt;sup&gt;1.073&lt;/sup&gt;) could be used to predict sheet erosion rate. Stream power (&lt;em&gt;R&lt;sup&gt;2&lt;/sup&gt;&lt;/em&gt; = 0.903) was a better predictor of sheet erosion than shear stress (&lt;em&gt;R&lt;sup&gt;2&lt;/sup&gt;&lt;/em&gt; = 0.882). However, predictions based on flow velocity, unit stream power, and unit energy were unsatisfactory. The stream power was an excellent hydrodynamic parameter for predicting sheet erosion rate. The sheet erosion process of grassland slope was also affected by the raindrop impact except the dynamic action of sheet flow. The combination of stream power and rainfall kinetic energy (&lt;em&gt;KE&lt;/em&gt;) among different rainfall physical parameters had the most closely relationship with the sheet erosion rates, which is also better than the stream power only, and a binary power function equation (&lt;em&gt;SE&lt;/em&gt; = 0.221 &lt;em&gt;&amp;#969;&lt;/em&gt;&lt;sup&gt;0.831&lt;/sup&gt;&lt;em&gt;KE&lt;/em&gt;&lt;sup&gt;0.416&lt;/sup&gt;) could be used to predict sheet erosion rate on grassland slope with &lt;em&gt;R&lt;sup&gt;2&lt;/sup&gt;&lt;/em&gt; = 0.930. The study results revealed the dynamic mechanism of the sheet erosion process on steep grassland in the loess region of China.&lt;/p&gt;

scholarly journals Karst bare slope soil erosion and soil quality: a simulation case study

Solid Earth ◽  
2015 ◽  
Vol 6 (3) ◽  
pp. 985-995 ◽  
Author(s):  
Q. Dai ◽  
Z. Liu ◽  
H. Shao ◽  
Z. Yang
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Infiltration Rate ◽  
Soil Infiltration ◽  
Seepage Rate ◽  
Rainfall Duration ◽  
Sediment Production ◽  
Correlation Degree ◽  
Slope Runoff

Abstract. The influence on soil erosion by different bedrock bareness ratios, different rainfall intensities, different underground pore fissure degrees and rainfall duration are researched through manual simulation of microrelief characteristics of karst bare slopes and underground karst crack construction in combination with artificial simulation of rainfall experiment. The results show that firstly, when the rainfall intensity is small (30 and 50 mm h−1), no bottom load loss is produced on the surface, and surface runoff, underground runoff and sediment production are increased with the increasing of rainfall intensity. Secondly, surface runoff and sediment production reduced with increased underground pore fissure degree, while underground runoff and sediment production increased. Thirdly, raindrops hit the surface, forming a crust with rainfall duration. The formation of crusts increases surface runoff erosion and reduces soil infiltration rate. This formation also increases surface-runoff-erosion-damaged crust and increased soil seepage rate. Raindrops continued to hit the surface, leading the formation of crust. Soil permeability showed volatility which was from reduction to increases, reduction, and so on. Surface and subsurface runoff were volatile with rainfall duration. Fourthly, when rock bareness ratio is 50 % and rainfall intensities are 30 and 50 mm h−1, runoff is not produced on the surface, and the slope runoff and sediment production present a fluctuating change with increased rock bareness ratio. Fifthly, the correlation degree between the slope runoff and sediment production and all factors are as follows: rainfall intensity-rainfall duration-underground pore fissure degree–bedrock bareness ratio.

scholarly journals Karst bare slope soil erosion and soil quality: a simulation case study

2015 ◽  
Vol 7 (2) ◽  
pp. 1639-1671
Author(s):  
Q. Dai ◽  
Z. Liu ◽  
H. Shao ◽  
Z. Yang
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Infiltration Rate ◽  
Soil Infiltration ◽  
Seepage Rate ◽  
Rainfall Duration ◽  
Sediment Production ◽  
Correlation Degree ◽  
Slope Runoff

Abstract. The influence on soil erosion by different bedrock bareness ratios, different rainfall intensities, different underground pore fissure degrees and rainfall duration are researched through manual simulation of microrelief characteristics of karst bare slopes and underground karst crack construction in combination with artificial simulation of rainfall experiment. The results show that firstly, when the rainfall intensity is small (30 and 50 mm h−1), no bottom load loss is produced on the surface, and surface and underground runoff and sediment production is increased with the increasing of rainfall intensity; secondly, surface runoff and sediment production reduced with increased underground pore fissure degree, while underground runoff and sediment production increased; thirdly, raindrops hit the surface, forming a crust with rainfall duration. The formation of crusts increases surface runoff erosion and reduces soil infiltration rate. Increasing of surface runoff erosion damaged crust and increased soil seepage rate. Raindrops continued to hit the surface, leading the formation of crust. Soil permeability showed volatility which were from reduction to increases and reduction, and so on. Surface and subsurface runoff were volatility with rainfall duration; fourthly, when rock bareness ratio is 50% and rainfall intensities are 30 and 50 mm h−1, runoff is not produced on the surface, and the slope runoff and sediment production presents a fluctuating change with increased rock bareness ratio; fifthly, the correlation degree between the slope runoff and sediment production and all factors are as follows: rainfall intensity > rainfall duration > underground pore fissure degree > bed rock bareness ratio.

scholarly journals Effect of tillage, slope, and rainfall on soil surface microtopography quantified by geostatistical and fractal indices during sheet erosion

2020 ◽  
Vol 12 (1) ◽  
pp. 232-241
Author(s):  
Na Ta ◽  
Chutian Zhang ◽  
Hongru Ding ◽  
Qingfeng Zhang
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Soil Surface ◽  
Rainfall Events ◽  
Tillage Practices ◽  
Surface Microtopography ◽  
Artificial Rainfall ◽  
Soil Surface Roughness ◽  
The Difference ◽  
Sheet Erosion

AbstractTillage and slope will influence soil surface roughness that changes during rainfall events. This study tests this effect under controlled conditions quantified by geostatistical and fractal indices. When four commonly adopted tillage practices, namely, artificial backhoe (AB), artificial digging (AD), contour tillage (CT), and linear slope (CK), were prepared on soil surfaces at 2 × 1 × 0.5 m soil pans at 5°, 10°, or 20° slope gradients, artificial rainfall with an intensity of 60 or 90 mm h−1 was applied to it. Measurements of the difference in elevation points of the surface profiles were taken before rainfall and after rainfall events for sheet erosion. Tillage practices had a relationship with fractal indices that the surface treated with CT exhibited the biggest fractal dimension D value, followed by the surfaces AD, AB, and CK. Surfaces under a stronger rainfall tended to have a greater D value. Tillage treatments affected anisotropy differently and the surface CT had the strongest effect on anisotropy, followed by the surfaces AD, AB, and CK. A steeper surface would have less effect on anisotropy. Since the surface CT had the strongest effect on spatial variability or the weakest spatial autocorrelation, it had the smallest effect on runoff and sediment yield. Therefore, tillage CT could make a better tillage practice of conserving water and soil. Simultaneously, changes in semivariogram and fractal parameters for surface roughness were examined and evaluated. Fractal parameter – crossover length l – is more sensitive than fractal dimension D to rainfall action to describe vertical differences in soil surface roughness evolution.

Surface runoff and soil erosion under eucalyptus and oak canopy

2016 ◽  
Vol 41 (8) ◽  
pp. 1018-1026 ◽  
Author(s):  
Arnold Thompson ◽  
Jerry D. Davis ◽  
Andrew J. Oliphant
Keyword(s):  
Soil Erosion ◽  
Surface Runoff

Integrated, spatial distributed modelling of surface runoff and soil erosion during winter and spring

CATENA ◽  
2018 ◽  
Vol 166 ◽  
pp. 147-157 ◽  
Author(s):  
Torsten Starkloff ◽  
Jannes Stolte ◽  
Rudi Hessel ◽  
Coen Ritsema ◽  
Victor Jetten
Keyword(s):  
Soil Erosion ◽  
Surface Runoff ◽  
Distributed Modelling

scholarly journals Hydrological Modeling in an Ungauged Basin of Central Vietnam Using SWAT Model

2016 ◽  
Author(s):  
Ammar Rafiei Emam ◽  
Martin Kappas ◽  
Linh Hoang Khanh Nguyen ◽  
Tsolmon Renchin
Keyword(s):  
Soil Erosion ◽  
Natural Hazards ◽  
Crop Yield ◽  
Surface Runoff ◽  
River Discharge ◽  
Hydrological Modeling ◽  
Assessment Tools ◽  
Actual Evapotranspiration ◽  
Ungauged Basin ◽  
Central Vietnam

Abstract. Hydrological modeling of ungauged basins which have a high risk of natural hazards (e.g., flooding, droughts) is always imperative for policymakers and stakeholders. The Aluoi district in Hue province is a representative case study in Central Vietnam, as it is under extreme pressure of natural and anthropogenic factors. Flooding, soil erosion and sedimentation are the main hazards in this area, which threaten socio-economic activities not only in this district but also those of the area downstream. To evaluate the water resources and risk of natural hazards, we used Soil and Water Assessment Tools (SWAT) to set up a hydrological model in the ungauged basin of Aluoi district. A regionalization approach was used to predict the river discharge at the outlet of the basin. The model was calibrated in three time scales: daily, monthly and yearly by river discharge, actual evapotranspiration (ETa) and crop yield, respectively. The model was calibrated with Nash-Sutcliff and an R2 coefficients greater than 0.7, in daily and monthly scales, respectively. In the yearly scale, the crop yield inside the model was calibrated and validated with RMSE less than 2.4 ton/ha, which showed the high performance of the model. The water resource components were mapped temporally and spatially. The outcomes showed that the highest mean monthly surface runoff, 700 to 765 mm, between September and November, resulted in extreme soil erosion and sedimentation. The monthly average of actual evapotranspiration was the highest in May and lowest in December. Furthermore, installing "Best Management Practice" (BMPs) reduced surface runoff and soil erosion in agricultural lands. However, using event-based hydrological and hydraulically models in the prediction and simulation of flooding events is recommended in further studies.

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