The aggregate movement during hillslope erosion process reflects the interaction among the aggregate breakage

raindrop impact and runoff transportation.The simulated rainfall experiment was designed to quantify movement characteristics of variously sized aggregates on hillslope farmlands of the black soil region

Northeast China.The results showed that the content of 0.25 mm water-stable soil aggregate was about 52%

24% lower than the contents obtained through dry sieving

while 1 mm soil aggregates contents was 83.8% lower.The majority of the water-stable soil aggregates was 0.25 mm aggregates.Under rainfalls of 50 and 100 mm/h intensities

0.25 mm aggregates contributed most of the aggregate loss

accounting for more than 80% of the total aggregate loss.The micro-aggregate loss rates were found significantly positively correlated with sediment concentrations under both rainfall intensities.As the rainfall time extended

the loss rate of micro-aggregate rapidly increased from the initial stage and then decreased in a short period of time and reached a relatively stable stage under 50 mm/h rainfall intensity;while under 100 mm/h rainfall intensity

the micro-aggregate loss rate increased quickly and increased slowly after the peak value was reached.The proportion of 0.25 mm aggregates loss and MWD of aggregates losses decreased with the increase of rainfall intensity

indicating that raindrop impact had played a great role in separating aggregates.