GEO-ENVIRONMENTAL PROBLEMS OFURBANIZATION IN CHINA
中国城市发展中的地质环境问题

Urbanization appears as a common trend in the development of various countries in the world, and particularly, the progress of urbanization is mostly prominent in the developing countries. In the last two decades the number and size of cities in China greatly expanded. The total number of cities in China increased from 213, including 11 with a population of more than one million, in 1970 to 622 at present, including 32 with a population of more than one million, presently. With the ongoing deepening of economic reforms and opening-up, urbanization will no doubt symbolize an important economic development of China in the coming century.City is a complex systerm incorporating physical environment with social environment. Large scale socio-economic activities and densely concentrated population in urban areas require the support of large scale engineering constructions, which have been becoming an iportant agent to utilize and rebuild nature' Thus, attention should be paid to environmental issues induced by engineering constructions in urbanization so as to provide the environmental conditions for urban sustainable development by coordinating engineering constitutions with the environment' The geoenvironment is one of important components of the physical environment, and macroscopically dominates the overall environment on a certain scope.The overall regionality of the physical environment in China, as a result of the interactions between the atmosphere, the hydrosphere, the biosphere and the lithosphere, is obviously governed by crustal endogenetic dynamics. The modern crustal geodynamic pattern of China continent dominates the overall terrain pattern that the terrain is steppedly distributed from the east to the west, forming three order terrain steps. The west part of the territory is the Qinghai-Tibetan plateau, while the east is marked by depressions of North China and Northeast China and formation of lowlands. Under the influence of the characteristics of terrain mentioned above, dry climatic condition was formed in the northwest part of China, whereas the southeast part is dominated by humid climate due to the intrusion of the oceanic atmospheric currents' The above terrain and climatic patterns control the overall physical environmental pattern and the distribution of natural disasters, and constitute the physical setting of urban geoenvironment.Various physical geologic and geographic settings usually are characterized by specific types of geoenvironment and combinations of environmental hazards. For instance, cities located in coastal lowland areas, such as Tianjin and Shanghai, are perplexed by land subsidence, seawater intrusion, flooding and plastic soft clay, while those in coastal hilly areas are additionally by landslide disaster. In cities situated in inland alluvial plains or inland basins, such as Xi'an and Beijing, ground crackings,surface collapse, desertification, salinization, swamping, landslide and debris flow are relatively