Response of rill erosion to rainfall types and maintenance on the Loess Plateau: Implications for road erosion control

Abstract

Although road erosion represents a threat to regional environmental and ecological security, limited evidence exists regarding the relationship between road erosion, rainfall, and road maintenance. In this study, we investigated the effects of different rainfall types on rill erosion and the degree of rill dissection of roads involving petroleum transportation and agricultural production in the hilly and gully region on the Loess Plateau of China from 2019 to 2021. During this period, 30 natural rainfall events occurred that were classified into four rainfall types using K-means clustering analysis.The results indicated that road erosion caused by large amount of rainfall with high intensity (LH-R) was 4.31, 3.82, and 3.48 times higher than that with small amount of rainfall with high intensity (SH-R), small amount of rainfall with low intensity (SL-R), and large amount with low intensity (LL-R), respectively. This highlighted the devastating impact of the LH-R on road erosion (the most severe of all types), with an average erosion rate of 527.04 t ha−1. Road erosion caused by SL-R events (most frequent) during the rainy season also deserves attention because of its cumulative impact on rill erosion. Moreover, compared to bare runoff plots and sloping farmlands, unpaved roads experienced a greater erosion rate due to upslope drainage areas and frequent human disturbance. In addition, the drainage system mitigates road erosion under LH-R, thereby reducing the average erosion rate by 56.42 %. We also found that road rehabilitation impedes the development of rills and diminishes the rate of road erosion compared to road segments without road rehabilitation.Collectively, the effects of rainfall types and maintenance activities on road erosion were assessed. The findings indicate that strengthening water and land management of upslope drainage areas, complementing the drainage system of unpaved roads, maintaining appropriate maintenance activities, and promoting vegetation coverage on the downslope of roads mitigate the resistance of unpaved roads to LH-R.