【作者】 杨波；

【导师】 王文龙；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2019， 硕士

【摘要】 神府东胜煤田因其巨大的煤储量成为世界七大煤田之一,露天开采是神东煤田主要开采方式,在开采过程中产生的大量弃土弃渣堆积而成排矸场和排土场,在晋陕蒙矿区星罗棋布地分布着大大小小的排土场超过几百个。排土场边坡土质松散,在暴雨和大风等气候条件下容易产生剧烈的水土流失。目前,植被措施已被广泛应用于排土场边坡防护和矿区土地复垦治理中。已有众多学者对排土场边坡水土保持进行了大量研究,但当前关于不同植被配置模式对排土场边坡的防蚀效益和防蚀机制尚不明晰。因此,本文以露天煤矿排土场边坡为研究对象,采用野外原位“放水冲刷”试验方法,以裸坡（LP）为对照,研究了9种植被配置模式（上冰草下沙蒿面积比例3:7坡面（CH7）;上冰草下沙蒿面积比例约为7:3坡面（CH3）;冰草坡面（QC）;冰草沙棘混合坡面（CG）;上裸坡下冰草面积比例1:3坡面（LC）;鹅绒藤坡面（ER）;上沙打旺下冰草面积比例1:3坡面（SC）;沙蓬沙打旺混合坡面（SS）;沙打旺坡面（SD））的排土场边坡产流产沙规律、坡面径流水动力学特征及侵蚀动力机制。阐明不同植被配置坡面的减水减沙效益和及其在各放水阶段的产流产沙贡献率,分析不同植被配置模式坡面植被根系差异特征及其对坡面产流产沙的影响,揭示排土场边坡不同植被配置模式的防蚀机理。研究结果可为矿区水土流失治理和生态修复提供一定的参考和指导。主要结论如下:（1）不同放水流量条件下,各坡面的径流率均在产流前期呈急剧上升的状态,后呈稳定波动的变化趋势;侵蚀速率随产流历时的延长呈先快速增长后波动减小的趋势。在5²5 L/min五种放水流量条件下,裸坡平均径流率、平均含沙量和平均侵蚀速率分别分布在2.40¹5.16 L/min、0.02⁰.91 g/ml和279.55¹0900 g/min之间;不同植被配置坡面平均径流率、平均含沙量和平均侵蚀速率分别分布在在0.07²0.57 L/min、0.001¹.36g/ml、0.48¹1162.32 g/min之间。植被配置模式防护坡面平均径流产沙均小于未防护的裸坡,而部分枯萎植被配置模式坡面则大于未防护的裸坡。（2）不同流量下,裸坡坡面径流流型均为紊流,而QC、CG、ER、SC、SS和SD植被配置模式坡面径流流型均随放水流量的递增由层流过渡到紊流状态。不同植被配置模式下坡面径流流态不同,随着放水流量的增大,各坡面径流流态均由急流变为缓流。各坡面径流剪切力、水流功率和径流动能随放水历时的变化过程差异较大,而裸坡的径流动能显著大于其它植被配置模式坡面,其中裸坡坡面径流剪切力、水流功率和径流动能分别分布在5.93⁷5.21 Pa、0.002⁰.079 N·m^-1·s^-1和0.015⁰.116 J,各植被配置模式坡面径流剪切力、水流功率和径流动能分别分布在0.09¹25.38 Pa、0.001⁰.234 N·m^-1·s^-1和0.004⁰.054 J之间。（3）QC、CG、ER、SS和SD各坡面土壤剥蚀率与径流剪切力、水流功率、径流动能和阻力系数之间呈极显著的幂函数或指数函数关系,其中土壤剥蚀率随着阻力系数的增大而减小,即土壤剥蚀率均可用径流剪切力、水流功率等水动力参数进行较好预测。（4）不同植被配置坡面在各放水阶段（5²5 L/min）的产流贡献率随放水流量的增大而增大,产沙贡献率在各放水阶段波动变化,且不同植被配置模式坡面各阶段贡献率差异较大。其中裸坡在各放水阶段的产流和产沙贡献率分别为5.46%³5.98%和7.60%²1.63%,CH7、CH3、QC、CG、LC、ER、SC植被配置坡面在各阶段的产流和产沙贡献率分别为0.21%⁵1.19%和0.10%⁶0.86%,而枯萎植被配置模式SS和SD坡面为1.38%³5.57%和1.83%³5.60%。坡面的侵蚀速率和径流率之间均呈极显著（R²=0.2696⁰.8603,P<0.01）的幂函数关系。（5）各防护坡面的根系特征指标差异明显。其中各植被坡面生物量密度和根系平均直径分别为0.15¹.09 kg/m³和0.88¹.48 mm;随着根系径级的逐渐增大,各防护坡面根长密度表现为“先增后减”的变化趋势,总的根长密度分布在634.8³357.83 m/m³之间;根表面积密度表现为“上升-下降-上升-下降”的变化趋势,总的根表面积密度分布在2.6¹1.39 m²/m³之间;根体积密度随根系径级的增大表现为“两侧小中间大”的特征,总根体积密度分布在为1472.24⁸509.29 cm³/m³之间。（6）相对于裸坡,CH7、CH3、QC、CG、LC、ER、SC配置坡面总的减水和减沙效益分别为25.58%、28.95%、20.68%、26.67%、15.39%、30.17%、42.01%和79.39%、87.44%、84.47%、49.96%、47.31%、54.83%和89.97%,而枯萎植被SS和SD配置坡面的产流和产沙分别增大6.40%、2.42%和30.81、21.17%%,其中直根系沙打旺和须根系冰草面积比例1:3配置模式减水减沙效益最好,具有最好的坡面防护能力。研究表明,植被混合配置坡面比单一植被坡面防护效果要好,且配置的比例因子不同坡面防护效益不同。而可能存在土壤退化和植被枯萎坡面无防护效益,会加速侵蚀的发生。（7）不同植被配置模式坡面的减沙效益受坡面植被根系的生物量、根长密度和根体积密度大小影响,当单位土体内植物的根系质量和根系总长度以及根系体积越大时则该植被配置模式坡面的抗侵蚀能力越强,当坡面土壤质地较差,且植被枯萎时,其各项根系指标均显著降低,导致坡面侵蚀加剧。更多还原

【Abstract】 Due to its huge coal reserves,Shenfu Dongsheng Coalfield has become one of the seven largest coalfields in the world.Open-pit mining was the main mining method of Shendong Coalfield.A large amount of spoil ground slag generated during the mining process is piled up into a gangue field and a waste dump,more than a few hundred large and small waste dumps were scattered in the Jinshanmeng Mining Area.The slope of the waste dump was loose,and it is prone to severe soil erosion under climatic conditions such as heavy rain and strong winds.At present,vegetation measures have been widely used in the slope protection of waste dumps and land reclamation in mining areas.Many scholars have done a lot of studies on soil and water conservation on the slope of waste dump,however,the current control erosion benefits and erosion-preventing mechanisms of different vegetation allocation models on waste dump slopes are still unclear.Therefore,this paper taken the slope of open pit mine waste dump site as the research object,and used in-site scouring method.Based on Plot BS（Bare slope）as control,We studied the regulation of runoff and sediment of the waste dump slope,flow hydraulic characteristics of slope and erosion dynamic mechanism of 9 planting patterns（the ratio of the Agropyron planted on the upper slope and Artemisia desertorum on the lower slope was 3:7（CH7）;the ratio of the Agropyron planted on the upper slope and Artemisia desertorum on the lower slope was 7:3（CH3）;Agropyron planted on the whole slope（QC）;Agropyron mixed with Artemisia desertorum in plantation（CG）;the ratio of the no planted on the upper slope and Agropyron on the lower slope was1:3（LC）;Cynanchum chinense planted on the whole slope（ER）;the ratio of the Astragalus adsurgens planted on the upper slope and Agropyron on the lower slope was 1:3（SC）;Agriophyllum squarrosum mixed with Astragalus adsurgens in plantation（SS）;Astragalus adsurgens planted（SD）on the whole slope）.Explain the water reduction and sediment reduction benefits of different vegetation configurations on the slope and the contribution rate of runoff and sediment yield in each discharge stage,and analyze the differences of vegetation root system characteristics and their effects on runoff and sediment yield on different slopes.Revealing the anti-erosion mechanism of different vegetation allocation patterns on the slope of waste dump.The research results can provide some reference and guidance for soil erosion control and ecological restoration in mining areas.Main conclusions are as follows:（1）Under different discharge flow conditions,the runoff rate of each slope shows a sharp rise in the early stage of runoff production,and then shows a trend of stable fluctuation.The erosion rate first increased rapidly and then decreased fluctuately with the prolongation of runoff duration.Under the five kinds of discharge flow conditions of 5²5 L/min,the average runoff rate,average sediment concentration and average erosion rate of bare slopes were distributed between 2.40¹5.16 L/min,0.02⁰.91 g/ml and 279.55¹0900 g/min,respectively.The average runoff rate,average sediment concentration and average erosion rate of vegetation slopes are distributed between 0.07²0.57 L/min,0.001¹.36 g/ml and 0.48¹1162.32 g/min,respectively.Among them,the average runoff sediment of the protected slopes of the non-degraded vegetation configuration pattern are smaller than the unprotected bare slopes,while the average runoff sediment of the degraded vegetation protected slope was larger than the unprotected bare slope.（2）Under different flow rates,the runoff flow patterns of bare slopes are all turbulent.In plot differernt vegetation（QC,CG,ER,SC,SS and SD）,runoff flow pattern of the slope transitions from laminar to turbulent flow with the increase of the discharge flow.Different vegetation allocation modes have different flow patterns of runoff on slopes.With the increase of discharge flow,the runoff flow patterns of each slope change from rapid flow to slow flow.The runoff shear force,stream power and runoff energy of each slope were different with the change process of water discharge duration,while the runoff energy of bare slope was significantly larger than other vegetation protected slopes.Among them,the runoff shear force,stream power and runoff energy of bare slope were distributed in 5.93⁷5.21 Pa,0.002⁰.079N·m^-1·s^-1 and 0.015⁰.116 J,respectively,the runoff shear force,stream power and runoff energy of non-degraded vegetation slopes were distributed in 0.09¹25.38 Pa,0.001⁰.234N·m^-1·s^-1 and 0.004⁰.041 J,respectively.（3）There was no significant relationship between the soil erosion rate of LP and SC slope with the Froude number and drag coefficient.In plot QC,CG,ER,SS and SD,soil detachment rate had a very significant power or exponential function relationship between runoff shear force,stream power,runoff energy,Froude number,Reynolds number and drag coefficient,in which soil detachment rate decreases with the increase of the drag coefficient,that is,the soil detachment rate can be better predicted by hydrodynamic parameters such as runoff shear force and stream power.（4）In plot bare slope,CH7,CH3,QC,CG,LC,ER,SC,SS,SD,the contribution rate of runoff increased with the increase of discharge flow rate at each water release stage（5²5L/min）,and the contribution rate of sediment yield varies fluctuated in each stage of water release,and the contribution rate of each stage of slope in different vegetation allocation modes varied greatly.Among them,The contribution rates of runoff and sediment yield of bare slopes in each discharge stage were 5.46%³5.98%and 7.60%²1.63%,respectively.The contribution rates of runoff and sediment yield of non-degraded vegetation slopes at each stage were 0.21%⁵1.19%and 0.10%⁶0.86%,The contribution rates of runoff and sediment yield of degraded vegetation slopes at each stage were 1.38%³5.57%and 1.83%³5.60%.In all the slopes,regardless of vegetation pattern,erosion rate and runoff rate formed an extremely significant power function relationship.（5）The root characteristics of each slope were significantly different,and the root characteristics of the non-degraded vegetation slopes were larger than that of the degraded vegetation slopes.The biomass density and root diameter of each vegetation slopes were0.15¹.09 kg/m³ and 0.88¹.48 mm,respectively.With the gradual increase of root diameter,the root length density of each protective slope shows the change trend of"increasing first and then decreasing".The total root length density ranged from 634.8 to 3357.83 m/m³;the root surface area density shows the trend of“rise-down-rise-fall”,and the total root surface area density was distributed between 2.6 and 11.39 m²/m³;The root bulk density showed the characteristic of"small on both sides and large in the middle"with the increase of root diameter,and the total root volume density was distributed between 1472.24⁸509.29cm³/m³.（6）Compared with the bare slope,runoff of the non-degraded vegetation slopes of CH7,CH3,QC,CG,LC,ER and SC was reduced by 25.58%,28.95%,20.68%,26.67%,15.39%,30.17%and 42.01%and sediment was reduced by 79.39%,87.44%,84.47%,49.96%,47.31%,54.83%and 89.97%.The runoff and sediment yield of the degraded vegetation SS and SD configuration slopes increased by 6.40%,2.42%and 30.81,21.17%%,respectively.Among them,the straight root system of Astragalus adsurgens and the fibrous root system of the Agropyron ratio of 1:3 configuration mode had the best effect of reducing water and reducing sand,and had the best slope protection ability.The research shows that the slope protection effect of the vegetation mixed configuration was better than that of the single vegetation slope,and the slope protection benefit was different with different proportion factor.The degraded vegetation slope had no protective benefits,which will accelerate the occurrence of erosion.（7）The sediment reduction benefit of different vegetation allocation patterns was affected by the biomass,root length density and root volume density.When the root quality of the plant in the unit soil and the total length of the root system and the root volume were larger,the erosion resistance of the vegetation slope was stronger.When the vegetation on the slope was withered and degraded,the soil and various root indicators were significantly reduced,resulting in increased erosion.更多还原