To explore the changes in rill erodibility (K value) 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 600 ml/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

K values were estimated at 0.000 2 m/s

0.000 5 m/s

and 0.000 9 m/s under drainage state

saturated state and seepage state

respectively

while the K values for soil of cultivated land were estimated at 0.000 3 m/s

0.000 9 m/s

and 0.001 8 m/s

respectively. Meanwhile

for the soil of waste dump land

K values were estimated at 0.002 3 m/s

0.066 9 m/s

and 0.094 6 m/s under drainage state

saturated state and seepage state

respectively. Those results indicated that K values 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 3 land use types due to different soil particle sizes. For all soils

soil K values were the highest under seepage condition due to high vertical hydraulic pressure

while soil K values were the lowest under drainage condition due to low vertical hydraulic pressure. At the same time

K values for soil under saturated condition was 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 K values 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.