Search

Different karst water features and related water resources are present both in southern and northern China. There are over 3,358 well-developed karst ground river systems with total discharges in the dry season of about 420times108 m3 in the main karst regions in the southern part of China. Exploitation rates are only 8–15%. Over 100 larger karst spring systems in the main karst regions of northern China cover a catchment area from 500 km2 to over 4,000 km2, of which the average discharge appears to be from about 1 m3/s to 13 m3/s and the exploitation rates are 70–80%. Six aspects of the eco-hydrological features of some typical karst regions in China comprising water environment, ecological features, materials and structures between parent rock and soil, bio-geological processes and palynological studies (spore-pollen) are discussed. Qualitative evaluation of eco-geology and rocky desertification in the karst regions should be based on the main karst ecological conditions as well as artificial, i.e., man-made impacts.

Karst collapse, caused by natural or artificial abstraction of groundwater, has been a focus of environmental geological problems for its ever-increasing hazardousness. The potential erosion theory and vacuum suction erosion theory, which reveal the origin of karst collapse macroscopically, are popularly accepted. However, a mathematic prediction criterion for karst collapse cannot be established only by these two theories. From a new perspective, this paper attempts to explain the microcosmic mechanism of karst collapse on the basis of these two theories. When the shear stress surpasses the shear strength of soil, a certain point or a certain plane in the unconsolidated soil covering karst caves will fail under the mechanical effects of water and air as well as its load-pressure, and with the increase of damaged points, a breaking plane appears and the soil on karst caves is completely damaged; as a result, the karst ground collapses. On the basis of the Mohr-Coulomb failure theory and previous studies, the paper presents a prediction criterion of karst collapse. Finally, by taking, for example, nine typical cases of collapse caused by pumping tests in Guizhou, the paper gives the calculation process of the model and proves its reliability.