Soil colloids mobilized from a sloping farmland during the flow process can act as a carrier of agricultural chemicals. On a purple soil sloping farmland( 1500 m2) in Sichuan Basin,fracture flow water sources were identified using the18 O tracing technique,and the dynamics of colloid transport were explored for two rain events on August 29 thand September 10 th,2014. The results showed that,in response to the rain events,both hydrograph and colloid concentrations of fracture flow showed a pattern of early r...