Morphological comparison and analysis of the causes of pothole formation in karst cave: An example from Shuanghe Cave of Guizhou Province

Shuanghe Cave is located in Wenquan town, 12 km west of Suiyang county, Guizhou Province. It is a multi-layer cave system, developed in the dolomite strata in the upper Cambrian Loushanguan group. The landscape of the area comprises peak-cluster depression, peak-cluster valley and peak-cluster canyon. Faults and joints of cave area are well developed, of which joints trend in the direction of NS and NW. Controlled by the lithologies and geological structures, the underground river has been developed, where the potholes occur along the underground river of Yinhe and Xiangshui caves in Shuanghe Cave system. The annual mean temperature of the area is 15.5 ℃ and annual precipitation is about 1,210 mm. In order to compare the difference in pothole morphology and formation cause in the two caves, the pothole geometric features including the length of hole axes, hole depth and trend direction of the potholes long axis were measured in the field, by using measuring tape and laser range device. Statistical results show that distribution area of the potholes in Yinhe cave is small, with a considerable number of the pothole. However, potholes in Xiangshui cave are widely distributed, with thousands of the holes occur along both sides of the cave channel. Geometrically, the pothole oblateness of Yinhe cave is generally higher than that of Xiangshui cave, while the hole depth/width ratio of theYinhe cave is higher than that of Xiangshui cave. Morphologically, the potholes are dominated by both “V” and inverted “Ω” types in the Yinhe cave, while in the Xiangshui cave the potholes of inverted “Ω” type are predominant. This is closely related to the two cave water dynamic condition, geological structure, bed load, bedrock, weathering.