A Study On The Prediction Of Moderate Population Size Of Urban Agglomerations Based On Population Carrying Capacity

Urbanization is an inevitable choice for Chinese-style modernization,and city clusters,as an important spatial carrier for urbanization,are an important platform for supporting coordinated regional development and leading national economic growth.The rise of urban agglomerations is conducive to breaking the barriers of administrative divisions,improving the level of urbanization,and promoting the complementary advantages of cities at different levels.Although the total area of China’s urban agglomerations accounts for only 25%of the country,it concentrates 75%of the country’s total population.As the core of promoting economic and social development,population directly affects the economic level and social progress of a region.Among them,the determination of the appropriate population size not only provides strong technical support for the balanced allocation of urban resources and factors,but also provides practical support for the balanced development of population,and the difference between the appropriate population,population carrying capacity and resident population can also reflect the population pressure of the city,so as to measure the development level of the city and the quality of life of the residents.Therefore,an in-depth study on the appropriate population size of urban agglomerations can help enhance the development potential of urban agglomerations and promote their coordinated development,which is of great significance to the balanced development of China’s population.Based on this,this paper takes the Yangtze River Delta city cluster from 2009-2020 as the research object.,first of all,by combining the index system method with the P-E-R model method,a multi-objective evaluation system based on economy,society,resources and environment is constructed.Then,based on the four scenarios set by the scenario analysis combined with the coupling coordination model,the coupling coordination degree of urban clusters is measured.,and the optimal development scenario is selected according to the development trend of the urban agglomeration simulated by the Markov chain.Finally,the GM-BiLSTM neural network is used to predict the urban agglomeration and the permanent population of each city,and based on the optimal development scenario and the established multi-objective evaluation system,the population carried by each system in the urban agglomeration and 26 cities in the urban agglomeration in 2030 is calculated,and the measured population carrying capacity is used as the carrier to scientifically predict the moderate population size of the urban agglomeration in 2030.The main research results show that:(1)In 2030,the permanent population size of urban agglomerations will be about 180 million,and the moderate population size will be about 160 million,the difference between the two will be about 200 million people,the permanent population size will exceed the moderate population size,and the population of urban agglomerations will still be relatively too much.(2)The economic system of the urban agglomeration can carry the highest population in 2030,about 280 million people;the resource system can carry the least population,about 0.7 billion people,and resources become a key factor limiting the future population development of the urban agglomeration.(3)The economic and social carrying populations of most cities are higher than the resource and environmental carrying populations,and the resident population scale is much larger than the moderate population scale.Specifically,the resident population scale of nine cities represented by Shanghai has exceeded the maximum population carrying capacity of all systems and the population burden is heavy,while the resident population scale of the remaining cities,although still within the carrying capacity,has approached the maximum carrying capacity.(4)The population development status of cities in the Yangtze River Delta urban agglomeration in 2030 can be divided into three categories:congested,dense and dispersed.(5)The economic and demographic pressure of urban agglomerations is still relatively rich;Although the social stress index of urban agglomeration population has exceeded the equilibrium point,it is not much different from the equilibrium point,and the carrying capacity is slightly insufficient;The resource problem has brought great pressure to the urban agglomeration in the Yangtze River Delta,and the population resource pressure index has exceeded the equilibrium point by nearly two times.The environmental pressure index of the population of the urban agglomeration exceeds the equilibrium point of 0.572,and the bearing capacity is slightly overloaded.The work and innovations in this paper mainly include:(1)Selecting urban agglomerations as the research object,taking the coordinated integration characteristics of urban agglomerations into consideration,and measuring the moderate population of urban agglomerations and individual cities within them based on the overall coordinated development trend of the Yangtze River Delta urban agglomerations;(2)The per capita indicators that are constrained by the changes in population and the development level of each system are selected to reconstruct the evaluation system,and the selection of indicators pays more attention to representativeness;(3)Based on the population carrying capacity,the index system method and the P-E-R model method are combined to construct a combined model to make the model more applicable.