The influence of loess cave development upon landslides and geomorphologic evolution: A case study from the northwest Loess Plateau, China

Loess caves, landslides, collapses, bank erosion and soil erosion, which are independently and interactively shaping the modern loess landscape, are widely distributed across the Chinese Loess Plateau. The study area is located in a small watershed in Huining County, Gansu Province, which is one of the areas with the strongest development of loess caves across the Loess Plateau. This area is an ideal site for studying geological hazards and geomorphic evolution on the Loess Plateau. Seventeen landslides and 176 loess caves with a density of 887 units/km2 were investigated with a UAV (unmanned aerial vehicle) and mapped by GIS (geographic information system). Using high-resolution UAV images and topographic data, we carried out an interpretation of loess caves, bank erosion and landslides; studied the spatial distribution and developmental patterns of loess caves, landform morphology and the relationship between loess caves and landslides based on GIS spatial analysis, mathematical statistics and field surveys; and analyzed the influence of loess microtopography on slope landforms. Finally, six typical evolutionary models of soil erosion-loess cave development-landslide occurrence-barrier dam formation are preliminarily proposed: the primary slope stage, early cave stage, accelerated cave stage, cave connecting stage, landslide creeping stage, and landslide-dam forming stage. This study is a useful exploration and an attempt to reveal the influence of loess cave development on slope stability and disaster chain effects.