Studies On The Environmental Impact Assessment Of Urbanization Development In The Pearl River Delta

As a social change phenomenon through the planet during the 20th century, urbanization is one of the most important research fields interested by socialists all the time. However, the scienctists were not interested in urbanization study. The researches of social change, population migration, life style change, agglomeration effect of economic activities, productive made transformation, change of social structure, organization and culture have been conducted relatively deeper. In developed country, urbanization had already completed during the course of industrial revolution. Therefore, the researchers of urbanization focus their eye in developing and new industrialised country at present.As the gradual propel of urbanization, urban population dilates promptly. And urban land expands rapidly. Some problems that will impede urban development emerge one another. In the course of practising urban sustainable development, some urban environmental problems became critical. So, the environmental impact of urbanization attracted attention from all people. The synthetical environmental impact assessment of urbanization becomes as a matter of course one of the experts' research fields.On the technical support of Remote Sensing (RS), Geographical Information System (GIS) and Global Positioning System (GPS), the urbanization process from late 1970s was investigated through the aspects of urban population and urban land used the method that combined social science with natural science in this thesis. The environmental impact of urbanization process was analysed through the aspects such as economic, traffic, urban district environment, geochemistrical environment of river water, population quality and so on. An environmental impact assessment model - "urban environment entropy model" was created on the base of thermodynamics entropy principle. And it was applied in the comprehensive assessment of environmental impact of urbanization in the Pearl River Delta Economic Zone. Through overall analysis and discussion, the following conclusions were drawn. Up to 2000, the Pearl River Delta Economic Zone has approached its seniorphase of urbanization. The population urbanization level was above 70%. Buturbanization developed rather uneven in the study area. Most of the regionswere in their middle phase of urbanization. Urbanization level of some counties was much higher than 70%. However, some counties still stayed at their junior phase of urbanization (urbanization level below 30%). While the process of population urbanization, urban land expansion appeared different spatial pattern at different period. At late 1970s, Guangzhou was the only center in the whole Pearl River Delta Economic Zone. To late 1980s, Shenzhen became another new urban expanding center. A new urban pattern, two-center, has formed in the Pearl River Delta Economic Zone. Urban land expanding shows a new situation that flowered all over the region at late 1990s. In the Pearl River Delta Economic Zone, there existed three typical spatial pattern of urban land expansion in late 1990s. They are: high density urban group along the belt of Guangzhou-Foshan; a spiderweb spatial urban land expanding pattern appeared along the belt of Shenzhen-Dongguan; in the two limbs of east and west of the Pearl River Delta Economic Zone, urban land of each county appeared a dotted and scattered form. During the period, urbanization led to large reduction of cropland in the Pearl River Delta Economic Zone. But as urbanization develops further, urban development will be not necessary to occupy lots of excellent land or cropland. It is completely possible to meet the land demand for urbanization through excavating the internal potential of urban land. And then urbanization would be favorable to improve the intensification degree of land use. In general, the increase of urban land and urban population tends to co-ordinate gradually. Urban land use will become reasonable. The integrated assessment model for environmental impat of urbanization base on the thermodynamics entropy principle - urban environment entropy model is reliable and available. Furthermore, the data needed in the model are easy to collect, that indicates the urban environment entropy model could be used in practice widely. Urbanization advanced the fast development for the regional economy, traffic and urban environment extremely in the Pearl River Delta Economic Zone. Furthermore, urbanization promoted the improvement of population quality to a very high extent simultaneously. But urban construstion deteriorated river water to some high extent. It led to qualitive water shortage locally in the Pearl River Delta Economic Zone. Though the river wate quality in most of the rural rivers can satisfy the standard for drinking water source. Most river sections in urbanarea were contaminated seriously. And resulted in strong stress on the regional water resource.This thesis was partially supported by the "Key program of NSF of Guangdong Province (021446)" and the "key program of the Geological Survey Bureau of Chinese (20001500012041-08)".