Distinguishing transport-limited and detachment-limited processes of interrill erosion on steep slopes in the Chinese loessial region

Distinguishing transport- and detachment-limited processes of interrill erosion on the basis of the ratio of interrill erosion rate (Q) to splash detachment rate (D) was investigated to fully understand interrill erosion processes. A modified experimental device was used to measure interrill erosion and splash detachment rates simultaneously at 12.23%, 17.63%, 26.8%, 36.4%, 40.40% and 46.63% slope gradients under rainfall intensities of 48 and 120 mm h−1. Results showed that the transport-limited (Q < D), detachment-limited (Q > D), and transport- and detachment-limited (Q < D & Q > D) processes were respectively included in individual rainfall event, which were influenced by slope gradient and rainfall intensity, and the transport-limited process changed to a detachment-limited process early when the slope gradients were steep. Furthermore, the ratio of interrill erosion rate to splash detachment rate under rainfall intensities of 48 and 120 mm h−1 increased from 0.006 to 36.91 and from 0.14 to 15.65 as the slope gradient increased from 12.23% to 46.63%, respectively. The research findings emphasise the importance of quantifying transport- and detachment-limited processes on steep slopes.