关键词: 城镇扩展, 生态环境效应, 监督分类法, LandsatTM, 西安

Abstract: In recent years,the research on Land Use/Cover Change(LUCC) and its effects on eco,environment has attracted more and more scientists to pay attention to it.However,the ecological effects induced by urban expansion were seldom covered.The objective of this paper is to reveal the urban expansion(1988～2003) in Xi'an region and the impacts it has on eco,environment by using Landsat TM satellite images. In this study,two TM images of the study area were used.After imagery pre,processing,which included atmospheric correction,geometric correction,and orthographic correction,super,vised classification was used to retrieve urban land use information,for it is the most common me,thod in obtaining land use/cover information.Then training samples were selected according to spectrum features,and the TM images of Xi'an region in 1988 and 2003 were classified into six land use types respectively,namely woodland,farmland,orchard,urban areas,water,body and uncultivated.Thus the urban expansion of Xi'an during the 15 years was acquired.Through the analysis of urban land use of Xi'an region in 1988 and 2003,it showed that during the 15 years,urban expansion in Xi'an was very quick.The urban area of Xi'an in 1988 was 59 711.31hm₂,but in 2003 it reached 75 043.53hm₂.With the help of transfer matrix of land use changes,the relationship between urban expansion and the other five land uses was also analyzed.This could tell us where the expansion came from.Finally,using related statistical data that we collected,the effects of urban expansion on eco,environment were analyzed. The main conclusions demonstrate that:(1)During the 15 years,the urban area of Xi'an region increased 25.68% from 1988 to 2003.(2)The urban expansion area was mainly converted from farmland,uncultivated land,orchard and water,body.A total of 23 718.60ha farmland was converted into urban area,which made the most important contribution to urban expansion.(3)The eco,environmental effects of urban expansion in the study area were not very optimistic.The pollution of water resources,Heat Island Effect and geological hazards were the three most obvious problems.Because of urban expansion and economic development,water pollution has induced water supply shortage in Xi'an region;with the continual increase of urban area which changed the ground feature,the annual mean temperature of Xi'an city has increased 1.9℃ from 1989 to 1999;and urban expansion also needed more water supplies,which resulted in overexploiting ground water that caused many geological problems like ground subsidence and split.

Key words: urban expansion, eco,environment, supervised classification, Landsat TM, Xi'an