Background Gravity erosion is one of the prevalent types of soil erosion in the hilly-gully region of Loess Plateau, which causes a large amount of soil erosion and serious harm. Gravity erosion inducing factors are very numerous and have complex interrelationships, which makes it difficult to study. Figuring out the environment in which gravity erosion exists and occurs, so as to construct more scientific and effective prevention and control methods, is an issue that needs to be solved urgently in the current research on soil erosion in hilly and gully areas of the Loess Plateau.

Methods We systematically studied the spatial distribution of 78 landslides, 26 collapses, and 108 slumps, the quantitative characteristics of erosion, and the relationship between erosion and gully in Wangjiagou watershed of Lüliang city, Shanxi province, by using unmanned aerial vehicle (UAV) measurements, remote sensing interpretation, and field surveys.

Results 1) Gully types had an impact on the extent of gravity erosion hazards. The classification of gully types was helpful in identifying areas where gravity erosion was active, with head-water gullies and valley-side gullies accounting for 88.5% and 81.4% of the corresponding number of gullies in the study area in terms of gravity erosion weight and area, respectively. 2) There was a correlation between gravity erosion and gully slope, and it showed significant variability in different types of gullies. The region of slope 30°-60° was the most serious area of gravity erosion in the hill-side gullies and head-water gullies, respectively, with approximately 2.57 and 1.19 times higher occurrence rate than the other regions. Gravity erosion in valley-side gullies and head-water gullies mainly occurred in the region of slope 0-30°. 3) The level of damage and type of occurrence of gravity erosion varied significantly across slope composition types, which may be directly related to the types of soils that make up the slope and the spatial distribution of soils.

Conclusions This study revealed the main areas and environments where gravity erosion exists and occurs in the loess hilly gully area, and by classifying the gully and slope refinement, the degree of influence of the gully-slope system on gravity erosion could be further quantified, which may provide a theoretical basis for the prevention and management of gravity erosion in the hilly-gully region of Loess Plateau.