Effects of extreme rainfall on the morphological characteristics and spatial distribution of shallow landslides under different land use patterns in the loess region of western Shanxi Province, northern China

Objective This paper aims to explore the influence of extreme rainfall on the morphological characteristics and spatial distribution of shallow landslides under different land use patterns.

Method In this paper, the morphological characteristics and spatial distribution of shallow landslides were investigated by UAV photogrammetry after the extreme rainfall from October 3 to 6, 2021 in the Small Watershed of Caijiachuan Farmland, secondary forest and plantation in Jixian County, Shanxi Province of northern China.

Result (1) Extreme rainfall induced 425 shallow landslides in three small watersheds, with a total volume of 82 000 m³. Among them, there were 179 landslides with a volume of 43 138 m³ in the small watershed of farmland, 196 landslides with a volume of 33 489 m³ in the small watershed of planted forests, and 50 landslides with a volume of 5 373 m³ in the small watershed of secondary forest. (2) The analysis of kernel density showed that the shallow landslides in the small watershed of farmland had the highest density, and the peak of kernel density reached 714 per km², and most of them were located on the erosion slope and the slope between farmlands. Most of the shallow landslides in the small watershed of secondary forest were distributed along ravines, and the shallow landslides in the small watershed of plantation were distributed in strips along the northwest-southeast ridge line. (3) Shallow landslides in small watershed of farmland were mainly concentrated in the slope range of 20°−50° and the slope direction mainly due east and southeast. Landslides in small watersheds of secondary forests were mainly distributed in slopes of 40°−50° and were less affected by slope aspects. Landslides in the small watershed of plantation were concentrated in the slope of 50°−60° and the slope aspects mainly due east and west.

Conclusion This survey shows that vegetation can effectively reduce the shallow landslides caused by extreme rainstorms in small watershed scale, especially the secondary forest has a better effect on preventing shallow landslides. Therefore, under the background of global climate change, it is of great significance to build imitation natural vegetation on the Loess Plateau to improve the function of soil and water conservation.