scholarly journals Rill Erosion on Slope of Spoil tips: experimental study of runoff scouring erosion in multiple times

2021 ◽  
Author(s):  
Yongcai Lou ◽  
Zhaoliang Gao ◽  
Fuyu Zhou ◽  
Jianwei Ai ◽  
Yunfeng Cen ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Morphological Characteristics ◽  
Development Stage ◽  
Scientific Basis ◽  
Rill Erosion ◽  
Transition Flow ◽  
Stream Power ◽  
Runoff Simulation ◽  
Experimental Conditions ◽  
Erosion Mechanism

Abstract. The soil erosion of the spoil tips seriously threatens the safety of people's lives and property and the surrounding ecological environment. Rill erosion is an important cause of water and soil loss in spoil tips. This study was conducted to investigate the process of rill erosion on the slopes of spoil tips, changes in the morphological characteristics of rills and the mechanisms of rill erosion. A Field runoff plot (5 m long, 1 m wide and 0.5 m deep) with three inflow rates (1.6, 2 and 2.4 mm min−1) and three typical slopes (28°, 32° and 36°) was used for runoff simulation experiments. The results showed that, compared with the slope and scouring times, inflow rate was the most important factor affecting rill erosion of the spoil tips. The development of rill mainly goes through three stages: the rill formation stage, the rill development stage and the rill adjustment stage. The overall predominance of parallel-shaped rills at all experiments suggested that the formation of rills was dominated by concentrated runoff. The average rill depth was the best indicator of rill morphology for evaluating rill erosion. The flow regimes under the experimental conditions were supercritical-laminar flow and supercritical-transition flow. The Reynolds number was the best hydraulic parameter for predicting rill erosion. The stream power was the best hydrodynamic parameter to describe rill erosion mechanism. These results contributed to further revealing the rill erosion mechanism on the slope of the spoil tips and provided a scientific basis for its soil erosion control.

scholarly journals Development of Rill Erosion On Bare Sloping Farmland Under Natural Rainfall Conditions

2021 ◽  
Author(s):  
Jingling Zhang ◽  
Lili Zhou ◽  
Donghao Huang
Keyword(s):  
Soil Erosion ◽  
Morphological Characteristics ◽  
Side Wall ◽  
Bare Soil ◽  
Scientific Basis ◽  
Initial Slope ◽  
Rill Erosion ◽  
Rainfall Events ◽  
Natural Rainfall ◽  
Sloping Farmland

Abstract Rill erosion is an important type of soil erosion and provide a basis for preventing and controlling soil loss on sloping farmland. This study was conducted in a standard runoff plot of bare soil (20 m length, 5 m width with a slope of 10 degrees) to monitored runoff and sediment processes during two continuous and two intermittent natural rainfall events, and observed the rill morphological characteristics after multiple rainfall conditions. We observed the runoff and sediment processes presented a pattern of multi-peaks for continuous rainfall events, and a pattern of single or two peaks during two intermittent rainfall events. The sediment yield rate with instantaneous rainfall intensity and runoff rate exhibited a peak lag phenomenon with 1–6 min. After multiple rainfall events, rill were identified as strip-shaped, V-shaped, and tree-branched distribution, and rills were mainly distributed in 5–20 cm width and 0–10 cm depth, and the mean rill length, width and depth increased 2.27, 0.30 and 0.16 times compared to the initial slope (R0). The side-wall collapse erosion was mostly greater than downcutting erosion in the slope section I, II and III. In conclusion, this study help to understanding the slope runoff and erosion mechanisms, and provide a scientific basis for soil erosion model on sloping farmland.

scholarly journals The effects of three micro-catchment practices on erosion and runoff dynamics for a typical soil slope on the Loess Plateau of China

2019 ◽  
Vol 99 (1) ◽  
pp. 46-59 ◽  
Author(s):  
Liquan Sun ◽  
Shufang Wu ◽  
Robert Lee Hill ◽  
Huili Guo ◽  
Hao Feng
Keyword(s):  
Soil Erosion ◽  
Loess Plateau ◽  
Crop Production ◽  
Linear Functions ◽  
Fish Scale ◽  
Transition Flow ◽  
The Loess Plateau ◽  
Stream Power ◽  
Cumulative Rainfall ◽  
Reduction Effect

Three micro-catchment measures that are named fish-scale pits (FSPs), artificial digging (AD), and contour plowing (CP) for soil erosion prevention are widely used in the Loess Plateau. To clarify the effectiveness of these measures in intercepting runoff and reducing erosion and the mechanism of water flow movement, intermittent simulated rainfall events was carried out in the 15° slopes with FSPs, AD, CP, and control slope (CK). The results demonstrated the following. (1) For cumulative rainfall <83 mm, three measures effectively intercepted runoff and reduced sediment compared with the CK. The runoff and sediment reduction effect of three measures gradually disappeared when cumulative rainfall increased to 83, 99, and 108 mm, and the sediment generation of the three measures successively exceeded that of the CK and was more than two times higher. (2) Laminar or transition flow occurred for the CK, and the flow pattern changed from subcritical to supercritical at 101 mm of cumulative rainfall. For three measures, the flow patterns became turbulent within a short time but remained subcritical. (3) A correlation analysis showed that the soil detachment rate, hydraulic shear stress, and stream power in the micro-catchment measures can be described using linear functions, which reduced the rill erodibility and enhanced the soil’s resistance to concentrated flow erosion. This research has important guiding significance on the rational and effective implementation of micro-catchment practices to prevent severe soil erosion and increase water storage for crop production on the Loess Plateau of China.

THE PHYSICAL BASIS OF SOIL EROSION: MECHANISM, PATTERNS OF EXPRESSION AND PREDICTION

2021 ◽  
Author(s):  
Valeriy Demidov ◽  
Oleg Makarov
Keyword(s):  
Soil Erosion ◽  
Soil Cover ◽  
Physical Basis ◽  
Soil Science ◽  
Educational Institutions ◽  
Soil Protection ◽  
Erosion Mechanism ◽  
The Past ◽  
Erosion Processes ◽  
Wide Range

The monograph summarizes the information over the past 20 years on the currently widely used. The textbook is intended for students of higher educational institutions, studying in the specialty of soil science, as well as specializing in erosion and soil protection. The textbook describes the physical basis and mechanism of erosion processes, based on some sections of hydraulics, hydrology, hydro-and aeromechanics, knowledge of which is necessary to understand the mechanism of water, wind and irrigation soil erosion. The main mathematical models and principles of forecasting the values of soil losses as a result of erosion processes are considered. The textbook will be useful not only for students and postgraduates studying in the specialty of soil science, but also for geographers, ecologists and a wide range of specialists interested in the problems of soil cover conservation and environmental protection.

The influence of different roll erosion control products to the particle size distribution of the soil sediment eroded on artificial slopes

2021 ◽  
Author(s):  
Romana Kubínová ◽  
Petr Kavka ◽  
Martin Neumann ◽  
Jan-František Kubát
Keyword(s):  
Particle Size ◽  
Soil Erosion ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Soil Aggregates ◽  
Erosion Control ◽  
Initial Condition ◽  
Rill Erosion ◽  
Rainfall Simulator ◽  
Soil Sediment

&lt;p&gt;In this contribution the particle size distributions of the soil sediment obtained from soil erosion experiments were analysed. All the tests were done on arable topsoil&amp;#8217;s, separately the size distribution of the soil aggregates and individual soil particles were evaluated. Soil erosion was initiated under the controlled conditions. CTU Prague laboratory rainfall simulator and field laboratory in Jirkov were used for this research. The rainfall was artificially generated with use of a nozzle type rainfall simulator. The sediment transported due to the surface runoff and rill erosion was collected from the discharge of the inclined soil erosion plots (slopes 20 &amp;#8211; 34&amp;#176;, slope length 4 m).&lt;br&gt;During each experiment, eight samples were collected. Four samples were collected during the first experimental rainfall. For the next ten days, the container was kept aside the rainfall. Afterwards, the raining with the rainfall simulator on plot (which now had different initial condition compared to the plot during the first experimental rainfall as the plot already contained erosion rills from the previous episode) has been resumed and another four samples were collected.&lt;br&gt;Experimental plots were vertically divided into two parts. On one part was an eel and on the second part were different types of rolled erosion control products (RECPs) &amp;#8211; Enkamat 7010, and 7020, Biomac-C, coir fibres K700 and K400, jute, Macmat 8.1, mulch, hay, nonwoven, fortrac 3D and triangle. The influence of RECPs to the particle size distribution was investigated.&lt;br&gt;Laser diffraction has been selected as a method to determine particle size distribution and device Mastersizer 3000 was used. By the comparison of the particle size distribution, of more than five hundred samples, the different response to the soil erosion mechanism and the influence of external factors (slope of the experimental plot, initial condition and presence of RECPs) on the particle size distribution and soil aggregates content in eroded sediment were investigated. It has been found that both the particle size and aggregates size distribution of the eroded sediment changes considerably in time.&lt;br&gt;This research is funded by the TH02030428 - &amp;#8222;Design of technical measures for slopes stabilization and soil erosion prevention&amp;#8221; and by the International CTU grant SGS20/156/OHK1/3T/11.&lt;/p&gt;

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;

Haematotoxicology: Scientific Basis and Regulatory Aspects

2002 ◽  
Vol 30 (2_suppl) ◽  
pp. 111-113 ◽  
Author(s):  
Laura Gribaldo
Keyword(s):  
Target Genes ◽  
Cell Types ◽  
Scientific Basis ◽  
Cancer Drugs ◽  
Experimental Conditions ◽  
Clinical Drug Development ◽  
Anti Cancer ◽  
Starting Dose ◽  
Life Threatening

Haematopoietic tissues are the targets of numerous xenobiotics. The purpose of in vitro haematotoxicology is the prediction of adverse haematological effects from toxicants on human haematopoietic targets under controlled experimental conditions in the laboratory. Building on its foundations in experimental haematology and the wealth of haematotoxicological data found in experimental oncology, this field of alternatives toxicology has developed rapidly during the past decade. Preclinical and clinical drug development for anti-cancer drugs differs from that for other pharmaceuticals, because of the life-threatening nature of the disease. Treatment with anti-cancer drugs at clinically efficacious doses usually induces serious side-effects. The design of preclinical toxicology studies for anti-cancer drugs is intended to identify a safe clinical starting dose, characterise toxicities that could be encountered in human clinical trials, and determine whether these toxicities are reversible, manageable, and predictable. Although the myeloid colony-forming unit (CFU-GM) progenitor is most frequently evaluated, other defined progenitors and stem cells, as well as cell types found in the bone-marrow stroma, can now be evaluated in vitro. Genetic damage to haematopoietic cells can occur in the absence of any overt haematological signs. The development of tissue-specific screening systems that are able to give information about the toxic effects of chemicals, drugs and environmental hazards on target genes is needed, in order to make preliminary decisions or to set priorities for selection among large groups of chemicals and possible drugs.

scholarly journals Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

2016 ◽  
Vol 64 (3) ◽  
pp. 237-245 ◽  
Author(s):  
Feng Qian ◽  
Dongbin Cheng ◽  
Wenfeng Ding ◽  
Jiesheng Huang ◽  
Jingjun Liu
Keyword(s):  
Soil Erosion ◽  
Sediment Yield ◽  
Rainfall Intensity ◽  
Purple Soil ◽  
Three Gorges ◽  
Slope Gradient ◽  
Stream Power ◽  
Yield Rate ◽  
The Three Gorges ◽  
Subsurface Runoff

Abstract Hydrological processes play important roles in soil erosion processes of the hillslopes. This study was conducted to investigate the hydrological processes and the associated erosional responses on the purple soil slope. Based on a comprehensive survey of the Wangjiaqiao watershed in the Three Gorges Reservoir, four typical slope gradients (5°, 10°, 15°and 20°) were applied to five rainfall intensities (0.6, 1.1, 1.61, 2.12 and 2.54 mm·min-1). The results showed that both surface and subsurface runoff varied greatly depending on the rainfall intensity and slope gradient. Surface runoff volume was 48.1 to 280.1 times of that for subsurface runoff. The critical slope gradient was about 10°. The sediment yield rate increased with increases in both rainfall intensity and slope gradient, while the effect of rainfall intensity on the sediment yield rate was greater than slope gradient. There was a good linear relationship between sediment yield rate and Reynolds numbers, flow velocity and stream power, while Froude numbers, Darcy-Weisbach and Manning friction coefficients were not good hydraulic indicators of the sediment yield rate of purple soil erosion. Among the three good indicators (Re, v and w), stream power was the best predictor of sediment yield rate (R2 = 0.884). Finally, based on the power regression relationship between sediment yield rate, runoff rate, slope gradient and rainfall intensity, an erosion model was proposed to predict the purple soil erosion (R2 = 0.897). The results can help us to understand the relationship between flow hydraulics and sediment generation of slope erosion and offer useful data for the building of erosion model in purple soil.

Vertical variation of soil erosion resistance in the water-level fluctuation zone of the Three Gorges Reservoir, China

2020 ◽  
Author(s):  
Hai Xiao
Keyword(s):  
Soil Erosion ◽  
Three Gorges Reservoir ◽  
Erosion Resistance ◽  
Three Gorges ◽  
Stream Power ◽  
Vertical Variation ◽  
The Three Gorges ◽  
Unit Energy ◽  
Water Level Fluctuation Zone ◽  
Soil And Water

&lt;p&gt;The operation of the Three Gorges Reservoir (TGR) altered the distribution of the soil properties, the plant community composition and biomass in the water-level fluctuation zone (WLFZ). However, the vertical variation of&amp;#160;soil erosion resistance in the WLFZ of the TGR is still unclear and need to be further evaluated. The objectives of this study were to assess&amp;#160;the&amp;#160;vertical&amp;#160;variation of soil resistance to rill erosion in the WLFZ of the TGR and to identify the factors influencing these variations. Soil samples from 150-155 m, 155-160 m, 160-165 m, 165-170 m and 170-175 m were taken along a slope profile at the same time from the WLFZ of the TGR area. All the samples subjected to scour under the combinations of five slope gradients (8.74%, 17.63%, 26.79%, 36.40% and 46.63%) and five flow rates (5, 10, 15, 20 and 25 L min&lt;sup&gt;&amp;#8211;1&lt;/sup&gt;) by using a slope-adjustable steel hydraulic flume (4 m length, 0.4 m width, 0.2 m depth).&amp;#160;The results showed that&amp;#160;soil properties and biomass parameters were affected by the elevations of the WLFZ.&amp;#160;The average&amp;#160;soil detachment capacity&amp;#160;fluctuated with the increase of elevation,&amp;#160;maximum and minimum value of&amp;#160;&amp;#160;which were located&amp;#160;at&amp;#160;the 165-170 m and 155-160 m,&amp;#160;respectively. The soil detachment capacity was significantly negatively correlated with MWD&amp;#160;(P&lt;0.05), but not positively correlated with other properties&amp;#160;(P&gt;0.05). &amp;#160;The rill erodibility also&amp;#160;fluctuated with the increase of elevation. Correlation analysis showed that rill erodibility&amp;#160;corresponding to runoff shear stress and stream power respectively had significantly negative correlation with&amp;#160;MWD&amp;#160;(P&lt;0.05), and rill erodibility&amp;#160;corresponding to unit energy of water-carrying&amp;#160;section had significant negative correlation with MWD&amp;#160;(P&lt;0.01). Therefore, the soil aggregate stability&amp;#160;was&amp;#160;the&amp;#160;major factor responsible for the vertical variation in soil erosion resistance.&amp;#160;In addition,&amp;#160;critical shear stress, critical stream power&amp;#160;and&amp;#160;critical unit energy of water-carrying section&amp;#160;ranged from&amp;#160;1.1950&amp;#160;to&amp;#160;1.6427 Pa,&amp;#160;from&amp;#160;0.0132&amp;#160;to&amp;#160;0.3045 N&amp;#8226;m&lt;sup&gt;-1&lt;/sup&gt;&amp;#8226;s&lt;sup&gt;-1&lt;/sup&gt;&amp;#160;and&amp;#160;from&amp;#160;0.0052&amp;#160;to&amp;#160;0.0062 m,&amp;#160;respectively,&amp;#160;all&amp;#160;of&amp;#160;them&amp;#160;showed obvious fluctuations with the increase of elevation.&amp;#160;These research results highlighted&amp;#160;the effect of&amp;#160;elevation&amp;#160;on&amp;#160;soil erosion resistance in the WLFZ and provide theoretical guidance for the establishment of soil and water loss prediction model as well as the development of soil and water conservation planning and controlling in the TGR area.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Effects of freeze-thaw on soil properties and water erosion

2021 ◽  
Author(s):  
Baoyang Sun ◽  
Feipeng Ren ◽  
Wenfeng Ding ◽  
Guanhua Zhang ◽  
Jinquan Huang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Erosion ◽  
Soil Properties ◽  
Field Experiments ◽  
Organic Matter Content ◽  
Chemical Properties ◽  
Water Erosion ◽  
Matter Content ◽  
Experimental Conditions ◽  
Freeze Thaw

Freeze-thaw erosion occurs primarily at high latitudes and altitudes. Temperature controlled freeze-thaw events dislodge soil particles and serve as a catalyst for erosion. This review paper provided an overview of the effects of freeze-thaw on soil properties and water erosion. The process of freeze-thaw cycles results in temporary and inconsistent changes in the soil moisture, and affects the soil’s mechanical, physical and chemical properties, such as the soil moisture content, porosity, bulk density, aggregates stability, shear strength and organic matter content and so on. The variation trend and range of the soil properties were related to the soil texture, water content and freeze-thaw degree. Furthermore, the soil erosion was affected by the freeze-thaw processes, as thawing and water erosion reinforce each other. However, research of different experimental conditions on indoor simulations have numerous limitations compared with field experiments. The use of indoor and field experiments to further reveal the freeze-thaw effect on the soil erosion would facilitate improved forecasting.

scholarly journals Morphological characteristics and transcriptome analysis at different anther development stages of the male sterile mutant MS7–2 in Wucai (Brassica campestris L.)

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Jian Wang ◽  
Yitao Yang ◽  
Lei Zhang ◽  
Shaoxing Wang ◽  
Lingyun Yuan ◽  
...  
Keyword(s):  
Male Sterility ◽  
Brassica Campestris ◽  
Morphological Characteristics ◽  
Development Stage ◽  
Phenylpropanoid Metabolism ◽  
Male Sterile ◽  
Pollen Abortion ◽  
Flower Buds ◽  
Flower Bud ◽  
Sterile Mutant

Abstract Background The discovery of male sterile materials is of great significance for the development of plant fertility research. Wucai (Brassica campestris L. ssp. chinensis var. rosularis Tsen) is a variety of non-heading Chinese cabbage. There are few studies on the male sterility of wucai, and the mechanism of male sterility is not clear. In this study, the male sterile mutant MS7–2 and the wild-type fertile plant MF7–2 were studied. Results Phenotypic characteristics and cytological analysis showed that MS7–2 abortion occurred at the tetrad period. The content of related sugars in the flower buds of MS7–2 was significantly lower than that of MF7–2, and a large amount of reactive oxygen species (ROS) was accumulated. Through transcriptome sequencing of MS7–2 and MF7–2 flower buds at three different developmental stages (a–c), 2865, 3847, and 4981 differentially expressed genes were identified in MS7–2 at the flower bud development stage, stage c, and stage e, respectively, compared with MF7–2. Many of these genes were enriched in carbohydrate metabolism, phenylpropanoid metabolism, and oxidative phosphorylation, and most of them were down-regulated in MS7–2. The down-regulation of genes involved in carbohydrate and secondary metabolite synthesis as well as the accumulation of ROS in MS7–2 led to pollen abortion in MS7–2. Conclusions This study helps elucidate the mechanism of anther abortion in wucai, providing a basis for further research on the molecular regulatory mechanisms of male sterility and the screening and cloning of key genes in wucai.

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