Unpaved road erosion after heavy storms in mountain areas of northern China

Abstract

More frequent extreme rainfall events associated with global climate change cause greater challenges for soil conservation. Severe erosion occurs on many unpaved roads since these structures create important water flow paths during heavy storms. The present research aimed to investigate the intensity and influencing factors of unpaved road erosion under varied land use and management conditions (sloping cropland, terraced cropland, forest & grass). The erosion occurred in the watersheds contributing runoff water to roads after the greatest rainfall event recorded in the mountain area of northern China caused by Typhon Lekima. The research was conducted in an agricultural-forest-dominated watershed based on field investigation and UAV-based image analysis. A road erosion level classification standard was given according to the occurrence of rills, ephemeral gullies, and gullies. Significant erosion happened on 67% of the unpaved roads; 42% of them suffered moderate to severe erosion in which ephemeral gullies or gullies developed. The average erosion amount from these roads was 2280.75 t ha-1 and was significantly influenced by the watershed land use type and management. The dominant factor governing unpaved road erosion associated with terraced cropland was vegetation coverage on roads. Drainage area was the most important factor for road erosion in sloping cropland and forest & grass land, and road gradient was also a critical factor. Terraces, and forest & grass in drainage areas significantly reduced unpaved road erosion by 85% and, 47%, respectively, compared to sloping cropland. More integrated measures should be used to prevent unpaved road erosion. The results of this research can be applied to road protection against erosion in heavy storms.