Change detection in piping, gully head forms, and mechanisms

Loess-derived soils in semi-arid regions are valuable resources. These regions have erosional landforms (e.g., piping, gully heads, and gullies) complexly produced by geo-environmental forces. Identification of the connections between landform patterns and the underlying geomorphological mechanisms is essential for understanding how erosive rainfall creates blind gully heads from pipes and gullies from gully heads. The goal of this study was to clarify the complex spatial interactions between geomorphological processes resulting from extremely intense extreme rainfall events. Fieldwork was conducted to map all collapsed pipes (single and multiple sinkholes), closed depressions, and gully heads using photogrammetric drones in 2018 and 2019 in a 2700-hectare area of loess-derived soils. In 2018, 837 pipes and 283 gully head locations were identified. In 2019, these numbered 1034 and 549. Geomorphic transformations were described statistically and the erosional landforms were compared to land-degradation trends. Piping and head-cut types are reflections of specific geomorphic conditions in the hilly loess topography. A conceptual model is proposed to characterize the landform shifts in loess deposits in four dynamic states. The spatial processes and interactions of collapsed pipes and gully heads reveal the natural processes underlying their formation and provide insights that my help to identify solutions to curtail destructive activities and mitigate the forces driving erosion in regions similar to the study area.