Karst distribution and development in the Pearl River Delta

The karst formation and development in the Pearl River Delta can be divided into three zones which have been developed in three geological stages and controlled by geological structure, ancient hydrological network and groundwater circulation. The area with strong karst is mainly distributed in the Hutian and Shidengzi formation. The horizontal distribution of karst is controlled by the petrochemistry which is the internal factor and plays a decisive role; and geological structure provides a channel for groundwater and plays a leading role in the development of karst. Vertically, the karst can be divided into four layers. The elevation of -35 m to -80 m is the space range where karst is extremely intense and is susceptible to underground construction. The zones with elevations of above -35 m and between -100 m and -400 m fall in the areas with moderate karst, where some constructions with appropriate protection measures may be done. Below the elevation of -400 m, karst still occurs but is very weak. The factors mentioned above should be taken into account in land planning and utilization of underground space in karst areas.