Study On The Influence Of Plant Roots On The Development Process Of Rills On Dump Slope In Mining Area

The Erdos region has a large number of soil dumping sites formed by coal mining,which are widely distributed and serve as important geomorphological units that contribute to soil erosion in the area.Among them,gully erosion is one of the main ways in which the soil on the slopes of the dumping sites is eroded,accounting for about 70% of the total slope erosion.Plant measures play an important role in preventing slope gully erosion,especially the plant root system can improve soil properties and structure,and effectively inhibit the development of gullies.However,the mechanism by which plant root systems affect slope gully erosion in dumping sites is still poorly understood,which directly affects the effectiveness of soil and water conservation and ecological environment construction in the area.Therefore,this study selected the typical dumping site slopes in a typical mining area in the Erdos region as the research object,and chose Suaeda salsa and Artemisia ordosica as typical representatives of fibrous and taproot plants,respectively.Using the in situ scouring test method,the study investigated the impact of these two different types of plant root systems on the development of gullies,runoff and sediment yield,and hydraulic characteristics on the slopes of dumping sites.The study aimed to clarify the mechanism by which plant root systems affect gully erosion,and to provide scientific reference for the effective configuration of soil and water conservation measures on dumping site slopes in mining areas.The main conclusions drawn from the study are as follows:(1)The gully width,depth,area,and volume were positively correlated with scouring flow rate.The effects of oilseed root systems,the mixed root systems of Suaeda salsa and Artemisia ordosica,and Artemisia ordosica root systems on controlling gully width development were not significantly different.However,the effect of the Suaeda salsa root system was the best,reducing the gully width by 31% compared to the bare land area.Plant root systems effectively inhibited the development of gully depth,reducing it by 14% to 75.3%compared to the bare land area.The average width-to-depth ratio of the bare land area was less than 1,and the gully type was "narrow and deep".The other three vegetation root zone areas had an average width-to-depth ratio greater than 1,and the gully type was "wide and shallow".Under the scouring flow rate of 2 L/min,plant root systems had a weaker inhibitory effect on gully area development.Under the scouring flow rate of 4 L/min,plant root systems effectively inhibited the development of gully area,with the Suaeda salsa root system and the mixed root system of Suaeda salsa and Artemisia ordosica having better inhibitory effects,reducing the gully area by 58.9% to 59.% compared to the bare land area.The Suaeda salsa root system had the best inhibitory effect on gully volume development,reducing it by up to77.1%compared to the CK area.(2)The root systems of plants effectively weaken the shear force and power of runoff,increase the runoff resistance coefficient,and the effectiveness of the action is ranked in ascending order as follows: Artemisia ordosica root system,a mixture of Caragana microphylla and Artemisia ordosica root system,and Caragana microphylla root system.The runoff rate and sediment yield of each plot are highly positively correlated with the scouring flow rate.The plant root systems significantly reduce the runoff rate and sediment yield of each plot,and the effectiveness of the action is ranked in ascending order as follows: Artemisia ordosica root system,a mixture of Caragana microphylla and Artemisia ordosica root system,and Caragana microphylla root system.The plant root systems have certain inhibitory effects on the erosion of gullies on the soil dump slope,and the effect of Caragana microphylla root system is the greatest,followed by a mixture of Caragana microphylla and Artemisia ordosica root system,and the effect of Artemisia ordosica root system is weakest.The sediment yield is linearly correlated with the shear force,power of runoff,resistance coefficient,and runoff rate(R2=.44 to.84,P<.05).The sediment yield increases with the increase of the shear force,power of runoff and runoff rate,and decreases with the increase of the resistance coefficient.Gully width,area,and volume(except for the CK plot)are significantly correlated with the shear force,power of runoff,runoff rate,and sediment yield.(3)The clay content,soil organic matter,and soil porosity between different soil layers in the same plot reach their maximum value in the-10 cm soil layer and their minimum value in the 20-30 cm soil layer.There is no significant difference in the soil particle composition,soil organic matter,and soil porosity between different soil layers in the bare plot.The root morphology index between different soil layers within the same plot is generally the highest in the-10 cm soil layer,and the deeper the soil layer,the lower the index value.The four root characteristic parameters,namely root surface area density,root volume density,root length density,and root mass density,between the plots in the-10 cm soil layer,which are most closely related to gully development,have significant differences,and the various root characteristics parameters basically follow the order of Caragana microphylla plot > mixture of Caragana microphylla and Artemisia ordosica plot > Artemisia ordosica plot.(4)Gully depth and volume are significantly or highly significantly correlated with the soil particle composition,organic matter content,and soil porosity of each plot.The larger the soil clay and silt content,organic matter content,and soil porosity,the smaller the soil sand content,and the stronger the inhibitory effect on the development of gully depth and volume.The inhibitory effect of plant root systems on gully erosion is ranked as follows: Caragana microphylla root system > a mixture of Caragana microphylla and Artemisia ordosica root system > Artemisia ordosica root system.(5)The gully depth,area,and root surface area density,root volume density,root length density,and root mass density are highly negatively correlated,and all root characteristic parameters are significantly negatively correlated with sediment yield,with the correlation coefficient showing r(root volume density)> r(root mass density)> r(root length density)>r(root surface area).The influence of plant root systems on the development of gullies mainly depends on changing soil characteristics.Both plant root systems and soil have important effects on the development of gullies.On the one hand,they directly participate in the development of gullies and affect the morphology of gullies.On the other hand,they indirectly affect the development of gullies through the influence on surface runoff(runoff power and resistance coefficient).