Development of Rill Erosion On Bare Sloping Farmland Under Natural Rainfall Conditions

Rill erosion is an important type of soil erosion and provide a basis for preventing and controlling soil loss on sloping farmland. This study was conducted in a standard runoff plot of bare soil (20 m length, 5 m width with a slope of 10 degrees) to monitored runoff and sediment processes during two continuous and two intermittent natural rainfall events, and observed the rill morphological characteristics after multiple rainfall conditions. We observed the runoff and sediment processes presented a pattern of multi-peaks for continuous rainfall events, and a pattern of single or two peaks during two intermittent rainfall events. The sediment yield rate with instantaneous rainfall intensity and runoff rate exhibited a peak lag phenomenon with 1–6 min. After multiple rainfall events, rill were identified as strip-shaped, V-shaped, and tree-branched distribution, and rills were mainly distributed in 5–20 cm width and 0–10 cm depth, and the mean rill length, width and depth increased 2.27, 0.30 and 0.16 times compared to the initial slope (R 0 ). The side-wall collapse erosion was mostly greater than downcutting erosion in the slope section I, II and III. In conclusion, this study help to understanding the slope runoff and erosion mechanisms, and provide a scientific basis for soil erosion model on sloping farmland.