Water-eroded channels are focal points for water, wind, and tillage erosion processes as they can function as pathways for sediment transport, sources or traps of sediments and topography features that alter the nature of soil redistribution by tillage. The linkages and interactions of different erosion processes around the channel area are complex and dynamic, not only during the period when the channel is created but also after it is created. The effects of channels on subsequent water and tillage erosion and their contribution to total soil erosion have not been examined. To fill this knowledge gap, we carried out three studies, focusing on the role of channels in water and tillage erosion processes and the assessment of total soil erosion.

In the first study, we examined the effects of a channel on tillage translocation. For downslope tillage, channels reduced total translocation, whereas, for upslope tillage, channels increased total translocation. For contour tillage, channels increased total translocation as well. The patterns of tillage translocation can be well explained by the balance of the trapping effect versus the energy-intensity-increase effect. Soil movement decreases when the trapping effect dominates and increases when other effect dominates. Additionally, a plot experiment examined the effects of an existing channel and tillage on water erosion. With an existing channel, runoff discharge and sediment export increased, whereas, with tillage, runoff discharge and sediment export decreased. When an existing channel was tilled, the effects of tillage dominated, while the existing channel only demonstrated some minor impacts.

In the third study, a modeling procedure was developed to integrate the Raster-RUSLE2, Ephemeral Gully Erosion Estimator and Modified Directional Tillage Erosion Model for simulating water and tillage erosion. This integrated approach incorporated insights gained from previous studies on interaction effects. The individual models provided reasonable estimations for specific erosion processes, while the integrated model accurately estimated total soil erosion across most field areas. However, higher errors and uncertainties were observed in gully areas, potentially due to their dynamic erosion processes or limitations in input data resolution and accuracy, indicating that the gully area is a weak point for soil erosion modeling.