以攀枝花市盐边县红格龙蟒矿山李家河排土场、未被开采过的矿区灌草地和耕地3种土壤为研究对象,基于土壤水蚀预报模型(WEPP)中的细沟侵蚀模型,采用100,200,300,400,500,600ml/min的流量对灌草地、耕地和矿山排土场土壤分别进行排水、饱和以及渗流状态下的冲刷试验,查明其可蚀性(Kr)的变化。结果表明:(1)径流剪切力与土壤剥蚀率之间存在较显著的指数关系(P<0.01);(2)流量与土壤剥蚀率之间存在较为显著的指数关系(P<0.01),土壤剥蚀率随流量的增加呈指数形式增加;(3)在排水、饱和及渗流3种水文条件下,灌草地土壤Kr值分别为0.000 2,0.000 5,0.000 9m/s,耕地土壤Kr值分别为0.000 3,0.000 9,0.001 8m/s,排土场土壤Kr值分别为0.002 3,0.066 9,0.094 6m/s。可见,在同一水文条件下,土壤Kr值均表现为排土场>耕地>灌草地;(4)在同一土地利用类型下,土壤Kr值均表现为渗流状态>饱和状态>排水状态,这是由于渗流状态下土壤同时受到垂直方向和地表径流的双重作用,导致土壤可蚀性最差,在饱和状态下,土壤抗蚀性也相应地变差,在排水状态下,由于地表径流可以自由下渗,土壤抗蚀性相对较好。综上可见,土壤中垂直水力梯度的变化会显著影响土壤可蚀性,矿山土壤经过人为扰动之后抗蚀性也会呈显著降低趋势,在未来土壤侵蚀研究中亟需进一步开展深入研究。

To explore the changes in rill erodibility(Krvalue)among soils in waste dump land,shrub grassland and cultivated land,soil samples were collected in the shrub grassland and cultivated land without mining, and waste dump land of Hongge Longmang Mine of Yanbian County,Panzhihua City.A series of scour experiments were carried out to simulate rill erosion process under water discharge rates ranging from 100 ml/min to 600ml/min in the study area.Changes in soil detachment rate under drainage,saturated and seepage conditions were also measured.Results showed that a significant exponential relationship between flow shear stress and soil detachment rate appeared (P <0.01).Meanwhile,a significant exponential relationship between flow discharges and soil detachment rates was also observed(P<0.01).For the soil of shrub grassland,Krvalues were estimated at 0.000 2m/s,0.000 5m/s,and 0.000 9m/s under drainage state,saturated state and seepage state,respectively,while the Krvalues for soil of cultivated land were estimated at 0.000 3m/s,0.000 9m/s,and 0.001 8m/s,respectively.Meanwhile,for the soil of waste dump land,Krvalues were estimated at 0.002 3m/s,0.066 9m/s,and 0.094 6m/s under drainage state, saturated state and seepage state,respectively.Those results indicated that Krvalues for the soil of waste dump land were higher than those for the cultivated land and shrub grassland.Significant differences in the rill erodibility were observed among soils in the three land use types due to different soil particle sizes.For all soils,soil Krvalues were the highest under seepage condition due to high vertical hydraulic pressure,while soil Krvalues were the lowest under drainage condition due to low vertical hydraulic pressure.At the same time,Krvalues for soil under saturated condition were higher than that under drainage condition,which may be because higher vertical hydraulic pressure appeared under saturated condition than under drainage condition. These results indicated that Krvalues of rill erosion varied among different vertical hydraulic conditions and impacts of hydraulic gradient of groundwater on soil erosion process should be paid more attention in further studies.