Environmental-geological problems impacting sustainable urbanization in the Pearl River Delta Economic Zone, Guangdong, China.

The urbanization of the Pearl River Delta (PRD) Economic Zone is progressing rapidly. Environmental-geological problems are the "by-product" in the process of rapid urbanization and a reflection of disharmony among man, geo-environment and ecosystem in the pan-metropolitan trend. The main environment-geological problems that have wide impacts on the sustainable urbanization include ground deformation in areas of soft soils, siltation of harbors, river courses and mouths and flooding-waterlogging induced by abnormal coastline shifts, contamination of water and soils, water shortages in terms of poor quality, tectonic instability and hidden karst collapses. According to the genetic types, these problems can be divided into the primary-dominant type, secondary-dominant type and primary-secondary mixing type. The key to sustainable urbanization lies in scientific utilization of environmental resources and reduction of the risk of environmental-geological problems (including geohazards). Due to negligence of applications of the results of urban geoscience work in the urbanization decision-making and practice and lacking of systematic urban geological work, the author suggests that it is necessary to carry out systematic urban geological work centering on environmental geology as rapidly as possible.