Background Gully erosion is an important cause of land degradation. In urban mountain parks, gully erosion is easy to occur due to its special topography and tourist influence. Longevity Hill in the Summer Palace is a typical urban mountain park. Under the influence of natural and human factors, especially the frequent tourist activities and engineering construction, the mountain channel erosion is frequent and the soil erosion is aggravated. Therefore, we chose the Longevity Hill as the research object, and analyzed the gully erosion intensity characteristics of the mountain as well as the distribution and morphological characteristics of the eroded gullies, aiming to provide reference for its mountain gully management.
Methods Based on the characteristics of roads, natural topography and landscape, the Longevity Hill was divided into 37 study plots. The eroded gully was investigated one by one with the plot as the unit. The gully density index was used to evaluate the erosion intensity of the gully in each plots. The distribution characteristics and morphological characteristics of the Longevity Hill erosion gully were statistically analyzed by SPSS27 software.
Results 1) The average gully density of 29 gully plots in the Longevity Hill is 3.19 km/km², and the average erosion intensity is intense. The average gully density of 37 plots in the whole study area is 2.50 km/km², and the average erosion intensity is moderate. 2) Gully erosion generally occurs in the Longevity Hill, and the more serious plots are mainly distributed in the north and south sides of the eastern mountain, and the gully erosion intensity of the eastern mountain is generally greater than that of the western mountain. 3) The distribution of eroded gullies in the Longevity Hill is more in the south slope than in the north slope, and more in the north slope than in the east slope. 83.4% of eroded gullies are distributed in the slope of 15°–30°. The development of gullies in the Longevity Hill is mainly manifested by the development of gullies, and the changes of gullies width and depth are not different.
Conclusions The distribution of eroded gullies in the Longevity Hill is mainly affected by the comprehensive influence of engineering construction and tourist activities. The development of gullies is mainly manifested in the development of gully length. Attention should be paid to the guidance of tourist routes and the regulation of hydrological paths. The results may provide reference for the gully management of the Longevity Hill.
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