Urban Growth Simulation Based On Equalized Public Facility Allocation

Since the reform and opening up in the 1980s,China has experienced an unprecedented rapid urbanization process.By 2019,the urbanization rate has reached60.6%.Rapid urbanization has caused problems such as the incoordination between land urbanization and population urbanization,the low quality of urbanization,and the unbalanced development of urban basic public services.In recent years,China has begun to focus on promoting the construction of new urbanization,among which promoting the equalization of public service facilities is an important aspect of the new urbanization with people oriented.Therefore,the state has proposed the urbanization road of"promoting the integration of urban and rural planning,infrastructure and public services".It is imperative to take into account the reasonable supply of public service facilities while promoting urbanization.In the research on the interaction between cities and public services,a large number of studies have shown that public services play an important role in shaping the urban spatial pattern.However,most of the current researches on urban growth take the construction suitability evaluation or expansion potential as the basis for urban growth,but the impact of public service facilities is not considered enough,lack of evaluation of spatial matching degree between public services and residents'needs.Therefore,this paper takes Changzhou,which has a high level of urbanization as an example,combined with GIS spatial analysis,network analysis,accessibility evaluation and other methods,comprehensively evaluates the equalization level of public services,and simulates the future urban spatial pattern based on the comprehensive accessibility of public services.The main contents and conclusions are as follows:(1)Analysis of the current situation of public service facilities configuration.Firstly,the spatial distribution characteristics of residential areas and public service facilities are analyzed from two aspects:spatial density and spatial agglomeration.As for the spatial pattern,differences and correlations between public service facilities and residential areas coexist,they both show the characteristics of agglomeration distribution in the downtown as a whole;The agglomeration intensity of basic education facilities and community health service centers is lower than that of hospitals and recreational and sports facilities;urban residential areas are distributed in a dual core distribution,with a high level of agglomeration,while rural residential areas are widely distributed in the whole region,with a relatively lower level of agglomeration.Then,based on the traffic network,this research analyzes the shortest transit time from residential areas to the public service facilities.As for urban residential areas,basic education facilities and community health services can be reached by walking within30 minutes,and general hospitals and sports facilities can be reached by driving within15 minutes.Except for hospitals and sports facilities,the average shortest travel time of various public services in rural areas is more than 10 minutes than that of urban residential areas.Based on the residents'living circle,the coverage rate of public service facilities is analyzed.On the whole,the coverage of all kinds of public service facilities in the study area is relatively high,and the coverage rate of various facilities is in the order of kindergarten>community health service center>primary school>middle school,general hospital(cultural facilities)>sports facilities,but the difference between urban and rural areas is still obvious.Overall,the coverage rate basically follows the law of gradually decreasing from the urban center to the outside.(2)Comprehensive accessibility analysis of public service facilities.The two-step floating catchment area method is used to evaluate the spatial accessibility of urban and rural residential areas for each type of public service facilities in the study area.The results show that the spatial accessibility of educational facilities of urban suburbs and townships is better than that of urban centers,which indicates that educational resources in rural areas are sufficient,while educational resources in the main urban area are slightly insufficient;the spatial accessibility of medical facilities in the main urban district is better than that of the suburban and township areas,the spatial accessibility of recreational and sports facilities in the downtown and suburban areas is better than that in rural areas,and the difference is obvious.This paper constructs a evaluation model of comprehensive spatial accessibility of public service facilities in the study area,and evaluates the comprehensive accessibility according to the model.The results show that central region of Xin Bei District has a high comprehensive accessibility of public service facilities,which is a potential area for urban development.However,in the downtown area,due to the high concentration of population,the residents'demand for public services is more competitive,so the accessibility is at a low level.(3)Simulation of urban land use growth constrained by public services.The urban expansion intensity index and Markov chain method are used to analyze the urban land expansion and forecast the area of urban land in the future.From 2005 to 2017,urban land continued to expand,but expansion rate gradually decreased.This is related to the fact that under the background of"new urbanization",the growth mode of urban land has gradually changed from"extensive"growth to"combination of incremental supply and stock tapping".It is predicted that the total urban land will increase by 35.60km~2 in2025 compared with 2017.Based on the control parameters corrected by sleuth model,urban land growth in 2025 is simulated.The results show that under the constraints of public services,the new urban land area will be 35.83km~2 in 2025,which is mainly distributed in the south of Xinbei District,the north of Zhonglou District,the south of Wujin District,and the riverside zone of northeast Xinbei District;without considering the constraints of public services,the new urban land area will be 59.19km~2,and the spatial layout is scattered,which is distributed around the existing urban land in a filling way.Through the comparative analysis of the results,it is found that under the constraints of public services,the new urban land has more advantages in the use of existing basic public service facilities.