Transportation of fine particles controlled by particles flocculation is a key feature of soil erosion on gentle slope land

•Distribution and sorting of sediments from gentle slope land were investigated.•The migration of fine particle sediments was more pronounced on gentle slope land.•Aggregation behaviour of particles controls the selective transport of sediment.•Sediments were predominantly transported as aggregates besides 2–20 μm particles. During water erosion, selective transport of eroded sediments reduces the fertility of surface soil and exacerbates the risk of waterbody pollution. At present, sloping farmland >10° (SFL10), which easily causes soil erosion, is the main research object. However, there has been relatively little focus on gentle slope lands (GSL). GSL refers to large fields with slope gradients of