Response of Road Rill Erosion to Rainfall Types and Road Maintenances on the Loess Plateau: Implications for Road Erosion Control

Although road erosion represents a threat to regional environmental and ecological security, limited evidence exists on the relationship between road erosion, rainfall and road maintenances. This study was monitored rill erosion intensity and road fragmentation of petroleum transportation roads and agricultural production roads in the hilly and gully region on the Loess Plateau of China, over a three-year period from 2019 to 2021. During the study period, 30 natural rainfall events were occurred and classified into four rainfall types by K-means clustering analysis, namely large precipitation and high intensity rainfall events (LH-R), large precipitation and low intensity rainfall events (LL-R), small precipitation and high intensity rainfall events (SH-R) and small precipitation and low intensity rainfall events (SL-R). Among them, LH-R cause the most serious road rill erosion and road surface fragmentation. The road erosion caused by small precipitation and low intensity rainfall events with the highest frequency is also worth focus on. Besides, we found that the erodibility of unpaved roads with drainage systems and regular maintenances activities is weaker than that of unpaved roads without drainage systems and regular maintenances. And compared with the natural hillslopes and monitored bare runoff plots, unpaved roads have become predominant sediment source of the watershed. On this basis, the unpaved roads erosion intensity and road fragmentation under different rainfall types were determined, the influence of rainfall types and maintenances activities on road erosion were assessed, and the suggestions for road erosion mitigation were proposed. Findings from our study indicate that, increasing more efficient drainage systems and providing artificial road surface recovery, which can be a promotion on road rill erosion control.