| Urbanization refers to the historical process of the transformation of human production and life style from rural to urban or town,which is manifested in the transformation of rural population to urban population and the continuous development and improvement of cities.In recent years,the urbanization in Hexi area of Gansu Province has developed rapidly with the urban boundary having been expanding in a large scale and the urban area has been increasing continuously.The study of the spatio-temporal change process of urban expansion in this region and the analysis of its changing characteristics at different stages have certain reference value for coordinating the balanced development between towns and rationally utilizing land resources and optimizing the spatial distribution of cities and towns.It also has important significance to speed up the rapid development of urban economy in Hexi region.The aims of our study is to extract the urban boundaries,the spatial and temporal distribution of urban areas,and the change of urban area by using the image data in the years 1986,1990,1995,2000,2005,2010,2015 of Hexi region.The average annual change speed and intensity,the standard deviation of urban spatial form,the shape exponent-circular ratio and so on,are statistically analyzed,and the spatial-temporal process and characteristics of urbanization in Hexi region are analyzed and summarized.We draw the conclusions as following:1.As to urban spatial pattern,There are more cities and towns in the eastern part of Hexi,and the distribution is relatively concentrated,and the number of towns in the west region is less and the distribution is scattered.Unlike the cities with large area,the town is relatively small which mainly Expand along the roads.Most of the expanding urban areas in Hexi are encroaching on farmland,while only a few are spreading to desert areas.2.In the past 30 years,the urban area in Hexi area has increased by about 28794.18 ha,about3.6 times that of 1986,with an annual average growth speed of 959.81 ha/a and an average growth rate of 12%.we find that the average area of city,county and town is increasing and the increasing range is decreasing in turn,the increase multiple is 4.4 times and 3.1 times?2.6 times,respectively.We alse find that the increment of average area of cities is extremely remarkable and the average area ratio of town in eastern region is larger than that of the middle,the west region.3.The urbanization process can be divided into three stages: 1986-2005(the intensity of expansion is weaker),2005-2010(the intensity of expansion is increased),2010-2015(the intensity of expansion becomes weaker),among those stage,the period of 2005-2010 is the most rapid stage of urban expansion in Hexi region).In the past 30 years,the speed of urban development in Hexi region has slowed down from Wuwei city in the east to Jiayuguan city in the west,and the region with intense urban expansion has shifted from the central and western regions of the Hexi Corridor to the central and eastern regions,the eastern region;The change speed of cities' s urban area is faster but the change intensity is low,to the town,the opposite is ture.4.The disequilibrium of the size of the urban area is significant in the city level and the county level which are in a discrete state,and the degree of dispersion of town is smaller.Among the cities,the circular characteristic of Jiayuguan city is remarkable,the other four cities is not.Considering the county-level cities,urban's circular characteristic of Wuwei and Jinchang is not obvious,Zhangye city and the circular characteristic in Jiuquan county city relatively tend to be obvious;The circular characteristics of town-level urban area are less significant than that of county(county-level city). |
PDF Full Text Request