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

Abstract 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.