Study On The Expansion And Driving Forces Of Construction Land In Case Of Taiyuan Urban

At the end of the 20 th century,along with the deepening of the global urbanization process,China’s urbanization has gradually entered a period of accelerated development.The Party’s 18 th National Congress has increased urbanization into a national strategy,which has further driven the pace of urbanization.Rapid urbanization has caused a series of urban problems such as the increase of urban population and the continuous growth of urban construction land.Therefore,it is particularly important to study urban expansion and its driving factors in making sustainable urban development decisions.Firstly,the paper combs the development of spatial pattern since the city of Taiyuan was built,and then based on multi-source data such as Landsat remote sensing imagery,DEM data,and statistical yearbook,further analyzes and studies the spatial and temporal expansion characteristics and driving forces of construction land in Taiyuan City after 1990.The main research results are as follows: 1.From the perspective of time and space,the characteristics of the expansion of construction land in the urban area of Taiyuan in the 1990 s to the present are analyzed.From a time perspective: Taiyuan’s urban construction land area has expanded from 195.78 square kilometers in 1990 to 416.50 square kilometers in 2015.It has grown by a total of 220.72 square kilometers in 25 years,with an average annual expansion area of 8.83 square kilometers,and an average annual expansion intensity of 0.63.The dynamic degree of expansion is 4.51%.Among them,the largest expansion area was between 2000 and 2005,reaching 57.37 square kilometers,with an expansion rate of 11.47 square kilometers each year and an expansion intensity of 0.82;the period with the smallest expansion area was from 1995 to 2000,and the area of expansion during the five years was only 30.47 square kilometers.The difference between the expansion speed and the maximum expansion speed is 5.38 square kilometers each year,and the expansion strength is also the smallest.In terms of expansion dynamics,the maximum expansion dynamics during the period of 1990-1995 was 4.40%,followed by the period 2000-2005,with the smallest being 2010-2015,and the expansion dynamics at this stage was only 2.49%.From the perspective of space: The center of gravity of construction land in Taiyuan City has shifted 1425.81 meters to the southeast in the past 30 years,and the largest transfer distance has reached 742.35 meters in 2000-2010.In the direction of each quadrant,there is a positive trend of expansion,with the largest expansion area to the south(57.57 square kilometers).The high-speed expansion areas are mainly distributed in Jiancaoping District,Xiaodian District,and Jinyuan District;the quadrants with high expansion intensity are concentrated in the southeast.Departments,southern and northern regions are distributed in small shops and sharp grasslands.The average annual expansion strength in the southeast is much higher than that in other quadrants.The average annual expansive intensity index is 1.52,which is a type of higher intensity expansion.After 1990,the fractal dimension of construction land in Taiyuan City has been below 1.5,except for a slight increase from 2000 to 2005,the overall showing gradually decreased.The compactness index was a minimum of 0.044 in 2005,and reached a maximum of 0.051 in 2015.Although there was a slight fluctuation in 25 years,the overall performance was an upward trend.Generally speaking,from 1990 to 2015,the expansion area,expansion speed,and expansion intensity of construction land in Taiyuan City are basically the same,while the change in expansion dynamics is different.The main direction of expansion of construction land in Taiyuan City is North and South.The direction and secondary direction are east-west direction.The high-speed expansion areas are mainly distributed in Jiancaoping District,Xiaodian District,and Jinyuan District.The trend of decreasing fractal dimension and increasing the degree of compactness indicates that the spatial irregularity of the construction land margin in Taiyuan City is As a result,urban land tends to be compact and economical.2.The expansion of construction land in Taiyuan City is the result of a combination of factors,including natural and human factors.The development and expansion are inseparable with many factors such as the physical and geographical environment,social and economic conditions,policies and planning of the region.In this paper,DEM data is used to obtain altitude and topographic gradient in Taiyuan City.Based on this analysis,we can see that the natural geography of Taiyuan City’s “three sides surrounded by mountains” influences the direction,form,and trend of urban expansion to the greatest extent.Policy and planning factors play a specific role in guiding the expansion of construction land in Taiyuan City within a certain period of time.Because the physical geography environment and policy and planning factors cannot be quantified,this study uses social and economic conditions to construct the driving force index system.Through the principal component analysis and linear regression analysis the core social economic driving factors for the expansion of construction land in Taiyuan City are the improvement of living standards of residents,rapid economic development,growth of fiscal trade,expansion of urban roads,population growth and investment in fixed assets.The all factors are highly correlated with the expansion of urban construction land,and the fitting coefficient is as high as 0.95 or more.