The style of soil collapse in Yuanmou valley and influencing factors of its formation

Gully erosion is the dominant process causing soil loss in Yuanmou valley, Yunnan, China. Soil collapse is a common process involved in gully development, yet has not been understood very well. Investigation of soil collapse leads to four different collapse types: falling, toppling, sliding, and exfoliating, each of which has unique characteristics of geology, topography, and soil. Examination of their characteristics indicates that the occurrence of soil collapse is controlled by the three factors: the typical geological structure of the Yuanmou Formation represented by the alternating layers of sand and clay, the vertical development of joints, and the specific soil properties under the special weather conditions, including a dry-hot climate and distinct wet and dry seasons.