(6)
Where S1 is the surface area of the runoff plot, S2is the projected area of the runoff plot.
Runoff path referred to the shallow trench formed by surface runoff, while the runoff path density was the total length of the runoff path per unit area. In this study, RTK-GPS was used to measure the runoff path, and hydrological analysis tool in ArcGIS was used for secondary inspection: