Development characteristics and causal analysis of karst collapses in Chengnan community, Yingde City, Guangdong Province

This research endeavors to investigate the development characteristics, spatial-temporal distribution, and cause of karst collapses in Chengnan community, Yingcheng Street, Yingde City, Guangdong Province. Various technological means such as ground investigation, geophysical exploration, and drilling were employed to examine the collapses discovered in the study area, along with systematic data collection on environmental geologic conditions, historical disasters, and water-level monitoring in the study area and its surrounding areas. The results show that: (1) The karst collapses in the study area constitute an extremely large geological disaster, affecting an area of 0.6 km², with 31 consecutive eruptions. Most of the surface collapse pits in the study area are small-scale, while a few are medium and large-scale. The planar shape of the collapse pits is primarily circular and elliptical, while the cross-section shape is mainly cylindrical. (2) The occurrence of karst collapses in the study area is influenced by geological structure, covering-layer of soil, atmospheric rainfall, hydrogeological characteristics, and human activities. Among these factors, geological structure, covering-layer of soil, and hydrogeological characteristics are considered as primary factors, whereas atmospheric rainfall and human activities act as inducing factors after a comprehensive assessment. (3) To conclude, the karst collapses erupted in the study area can be categorized as “the mode of collapse near rivers in subsurface karst areas”. During the causal analysis, priority should be given to considering water level fluctuations, pumping, and drainage. Subsequently, other influencing factors should be taken into account based on specific conditions, providing valuable insights for future research on karst collapses erupted near rivers.