| Most of the old industrial cities in Northeast China experienced the trend of population loss and urban shrinkage while experiencing the―Northeast Phenomenon‖and―New Northeast Phenomenon‖,and urban shrinkage is a double-edged sword for urban development.The population density of the city has been reduced,and a large amount of idle land has been generated,which has brought about the possibility of adjustment of\industrial structure and land use structure,but this"probability"is based on the correct cognition and effective grasp of urban shrinkage.Therefore,master the characteristics,types,and driving mechanisms of the shrinkage of the old industrial cities in Northeast China,seize the opportunity of urban shrinkage,and use the theme of―smart shrink‖to transform the land use structure and improve land use efficiency,thereby realizing the optimization of industrial structure and promoting the city benign development is particularly necessary.The study took Siping City,a typical old industrial city in Northeast China,as a research area.The spatial and temporal evolution characteristics of land use and urban land use in Siping City were explored from two different perspectives:macro and micro.On this basis,quantitative study on the phenomenon of urban shrinkage in Siping City was carried out from three aspects of population,economy and land use,and the existing problems were deeply analyzed,and the driving mechanism and type characteristics of urban shrinkage of Siping City were determined.Based on the effective mode of developed countries to cope with urban shrinkage,and aimed at the phenomenons and characteristics of urban shrinkage of Siping City,the feasibility model of the smart shrink of the land in the old industrial city of Northeast China was proposed,based on this model,the study used the SD-MOP model to simulate the smart shrink of the land in Siping City.The aim was to provide a theoretical basis for the shrewd shrinkage and sustainable development of the land of old industrial cities in the northeast under the background of urban shrinkage.The main conclusions were as follows:(1)In 2001-2016,the construction land in Siping City increased sharply,and the total area increased by 3441.05 hm~2,and the area ratio increased from 11.5%to 16.1%.From2001 to 2016,the conversion between various types of land in Siping City was relatively frequent.The conversion of cultivated land,forest land and grassland to construction land,and the conversion of forest land and grassland to cultivated land were the main directions.There were 20 land conversion trajectories in Siping City from 2001 to 2009.In2009-2016,there were 11 land conversion trajectories in Siping City,and the spatial trajectories of conversion of cultivated land,forest land and grassland to construction land were mainly distributed in the periphery of the built-up area of Siping City.(2)The intensity of urban land expansion in Siping City from 2001 to 2009 was higher than that in 2009-2016.From 2001 to 2009,the urban land expansion direction of Siping City was mainly located in the east-south east,west-northwest,north-northwest,southeast-south and north-northeast..In 2009-2016,the main expansion direction of urban land in Siping City was located in three directions:east-southeast,west-southwest,west-northwest.With the adjustment of the urban development center,The center of gravity of urban land use in Siping City was constantly shifting.From 2001 to 2009,the center of urban land use in Siping City gradually moved to the northeast.From 2009 to2016,the center of gravity of urban land moved to the northwest,and mainly in the direction North Mobile was the mainstay.In addition,the land use structure of urban land in Siping City was not reasonable,and the land occupied by residential land,public management and public service industry was too high,and the proportion of industrial and mining land was high too.In 2016,the proportions of green and square land,roads and transportation facilities land in Siping City were only 7.35%and 8.38%,which did not meet the proportion of the corresponding urban land use standards in the<Urban land classification and construction land planning standards>(GB50137-2011).(3)In 2001-2016,there was a multi-dimensional shrinking phenomenon of population loss,economic downturn and idle land in the city of Siping,and the shrinkage mainly occurred in 2010-2016.In 2010 and 2011,Siping City experienced a loss of registered population and permanent resident population,and a decline in the size of the population.The decline in the population size of Siping City occurred simultaneously in the overall and urban central areas of Siping City.At the same time that the population size of Siping City was declining,the degree of population structure aging and degeneration were increasing.The proportion of the population over 60 years old in the total population had increased from 10.14%in 2001 to 21.41%in 2016.From the spatial analysis of population shrinkage,the population shrinkage in Siping City had experienced a period of change in the―central city-suburban township area-central urban area-total shrinkage‖,and the areas with high contraction were mainly concentrated in the central city;The growth rate of total GDP and total fixed asset investment in Siping City from2001 to 2016 were declined and reduced.As a typical old industrial city in Northeast China,Siping City has a single industrial structure.The proportion of the secondary industry in the national economy was much higher than that of the primary and tertiary industries.The traditional industries,especially the heavy chemical industry,dominated the industrial development.The area of urban idle land in Siping City had increased significantly from 2001 to 2016,from 47.34hm~2 in 2001 to 583.00 hm~2 in 2016,and the industrial and mining warehousing land,residential land were mainly idle,the idle land mainly concentrated in the old city area in 2001.The concentrated distribution of idle land in 2001-2016 was highly spatially overlapping with areas with high population shrinkage and heavy chemical industry clusters.(4)The driving forces of urban shrinkage in Siping City from 2001 to 2016 mainly included industrial structure,people’s living standards,infrastructure construction,land use,population structure and employment divisors in economic,social and demographic factors.Among them,the industrial structure and living standards were the main controlling divisors and the main driving force.Infrastructure construction was the second main component,land use was the third main component,and the population was the fourth main component.Through further analysis of the driving mechanism,the lower economic development and people’s living standards were regarded as the imbalance of regional development.The driving factors were interrelated and interacting with each other and cause each other.The single industrial structure of Siping City was the root of other drivers.Judging from the formation of the urban shrinkage type in Siping City,Siping City was a unban shrinkage under the influence of the industrial decline of the old industrial city in Northeast China.Judging from the spatial form of idle land,the urban shrinkage of Siping City experienced the evolution process of―Perforated Type-Circle Type-Circle Cake Type‖.Judging from the coordination relationship between population,economy and land use,the coordination relationship between population,economy and land use in Siping City was in a stage of serious disharmony.(5)A sustainable and high-density smart development model of land use was proposed.The primary problem to be solved was to deal with the large amount of idle assets generated by the decline of leading industries and population loss in Siping City.According to the proposed feasibility model of smart shrink of land use,the SD-MOP model was used to construct the smart shrink system model based on Siping City’s overall land use and urban land use,namely the macro and micro land use smart shrink model.From the perspective of economic efficiency and the coordinated development of―economic-ecological‖benefits,the SD optimization scheme and SD-MOP optimization scheme of land smart shrinking were obtained through simulation of the system.Through the comparative analysis of the operation results of the two schemes,it was believed that the SD-MOP land use optimization plan aiming at the coordinated development of―economic-ecological‖effectively solved the problem of excessive land use rate,population density,excessive expansion of construction land,and unreasonable land use structure in the urban shrinkage process in Siping City.It would help to optimize the quantitative structure,hierarchical structure and benefit structure of land resources in the old industrial city of Northeast China.On the basis of improving land use efficiency,ecological security and food security were maintained,industrial structure was optimized,and environmental pollution was alleviated.So the SD-MOP optimization program was a scientific and feasible plan to achieve sustainable,high-density and shrewd land use in Siping City. |
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