Research On Hangzhou Urban Expansion And It's Driving Mechanism Based On Remote Sensing

With the rapid development of urbanization, urban development has become the theme of global development in the 21st century. It is not only reflected in the rapid development of urban population and economy, but also rapid expansion of the urban space. A research on process and trend and driving mechanism of urban expansion has caused wide attention in academic circles.Remote sensing is a new science and technology as 1960s.Because of its strong timeliness, comprehensive and comparability, high efficiency, accuracy, macro dynamic, large-area of synchronous observation etc; remote sensing has become an important means of monitoring uran expansion.This paper takes Hangzhou city as researched area and extracts remote sensing information of its urban expansion from MSS/TM remote sensing image in 1984,1994 and 2005, by visual interpreting method, NDBI index method and maximum likelihood method. By remote sensing information extracted, this paper analyzes Hangzhou urban expansion characteristics using qualitative and quantitative methods from its space, quantity, dynamic attitude and intensity.Combined with social and economic statistical data, this paper further explores the driving factors of Hangzhou urban expansion by PCA model, and predicts three major social and economic factors which influence Hangzhou urbanization by BP neural network model.The research gets the following main conclusions:(1)Analysis of remote sensing information of Hangzhou urban extracted, the result shows that:①From the analysis of space:In addition to the southwest direction of Hangzhou urban where the Xihu Lake and Beigaofeng located in, other direction is remarkable expansion from 1984 to 2005, especially from 1994 to 2005. The appearance of Hangzhou urban belongs to "fan-shaped expansion" with "axial extension". Future expansion towards Xiao Shan and Yu hang district will be rapid, especially towards Xiao Shan district.②From the analysis of urban expansion area:Urban area expands 72.38 square kilometers from 1984 to 1994, and 116.08 square kilometers from 1994 to 2005. Visibly, the annual increased area is 6.58 square kilometers in the first 11 years; and 10.55 square kilometers in the last 11 years. Annual average speed of Hangzhou urban expansion is from fast into high.③From the analysis of urban expansion dynamic attitude:It is respectively 10.51% and 7.82% from 1984 to 1994 and from 1994 to 2005. Visibly, if the area of the former period takes as the benchmark, annual average growth rate of Hangzhou urban area is from the original medium-speed into slow. Dynamic attitude can also have another kind of formula; the calculation result shows that percentage of urban area change is respectively 115.57% and 85.98%. Urban area expands 1.2 times in the first 11 years, and 0.86 times in the last 11 years. Visibly, if the area of the former period takes as the benchmark, its expansion also becomes slow.④From the analysis of urban expansion intensity:if the total land area of Hangzhou urban takes as a benchmark, the intensity is respectively 1.04% and 1.55% from 1984 to 1994 and from 1994 to 2005. The intensity of Hangzhou urban expansion is from medium-speed into fast.(2)The paper reduces 15 major social and economic factors which influence Hangzhou urban expansion to four comprehensive driving force factors by PCA model.The research result shows that economic growth and industrial development is the first driving force, economic growth is the most fundamental and important factor which cause Hangzhou urban expansion, the development of industries especially industrial structure change, to some extent, accelerates urban expansion. Urban basic construction is the second driving force; it is direct driving force which leaded to urban expansion. The development of urban population is the third driving force; it is an original driver of Hangzhou urban expansion. Traffic development is the forth driving power; it has directionality role in Hangzhou urban expansion and influences the external form of Hangzhou urban. In addition, the result shows that their driving role in Hangzhou urban expansion has been enhanced each year by the analysis of the comprehensive score of the four comprehensive driving forces. Finally, the paper forecasts GDP, the third industry production value and the non-agricultural population which influence Hangzhou urban expansion by BP neural network model. Prediction result provides scientific reference for Hangzhou municipal government formulating relevant decisions and urban expansion project.The research in this paper provides some reference for scientific management and planning of Hangzhou urban construction land, and for the reasonable control of urban expansion, makes Hangzhou keep healthy and rapid development momentum in urbanization process in the future. At the same time, it can provide reference for the research of other coastal cities expansion.