Research On Evaluation Of Green Development Of Cities In The Yangtze River Economic Belt And Its Temporal And Spatial Characteristics

Nowadays,green development has become an important theme for urban and regional development in the worldwide.Its concept of emphasizing the coordinated development of resources,environment,economy and society has been widely agreed.The Fifth Plenary Session of the Eighteenth Central Committee of the Communist Party of China even included green development in the "Five Development Concepts".The Yangtze River Economic Belt has been the main axis of China’s promotion of new-type urbanization and the starting area for implementing sustainable development strategies.It has attracted more attention for its green development with the goal of "grasping the big protection and not carrying out big development".In order to achieve a balance of protection and development in the Yangtze River Economic Belt,its green development status needs to be fully understood.However,the current research on the green development of the Yangtze River Economic Belt pays less attention to the dynamic characteristics of the city.Existing assessment frameworks often overlook the of multi-system coordination which is the connotation characteristics of the green development.At the same time,these articles lack the analysis of the rules of inter-urban interaction.These problems have caused a lack of understanding of the green development status of cities in the Yangtze River Economic Belt.In view of this,this paper uses the improved green development assessment framework to evaluate the green development level of the 126 cities in the Yangtze River Economic Belt from 2008 to 2017 and clarify its evolution characteristics in time and space.Then the key influencing factors is analysed from the internal and external perspectives with the help of spatial Markov chains and stumbling degree model.BP neural network is also used for short-term prediction of green development level.Finally,this paper puts forward specific coping strategies based on the analysis results.This article not only improves the green development assessment framework,but also makes up for the deficiencies in the external space impact and prospective forecast in the study of urban green development in the Yangtze River Economic Belt.It provides a new perspective and method for in-depth understanding of the green development process and trends of the river basin.This paper is divided into three parts.The first part is the research foundation.It is the preface and a summary of related research progress,including the subject source,research background,objectives,significance,framework,methods and general review all over the world.The second part is the construction and empirical application of the evaluation system.First,this paper breaks through the limitations of the current evaluation which focuses on the ability level and constructs a green development evaluation framework of "capability + coordination + synthesis" with the goal of joint development.On this basis,the specific evaluation indicators suitable for the Yangtze River Economic Belt are selected and used to dynamically evaluate the green development level of the cities in Yangtze River Basin.Next,the mathematical characteristics of the evaluation results and its spatial pattern are analyzed.Although the overall level of the river basin is getting better,the gap of capability level grows wider and the coordination level has been stuck.Many cities with high coordination level represented by Wuhan,Nanjing and Wuxi are in decline.In terms of subsystem level,the economic and social system has strong development momentum,while the resource and environmental system makes slow progresses and fluctuates wildly.The positive interaction among them is not yet obvious.By comparing the relationship between the ability and the coordination level,it can be found that the capability level of cities does not determine whether their subsystems are in the breaking-in period or high coordination stage.The relationship has gradually eased,and the river basin has basically developed towards the goal of mutual promotion of capacity and coordination.A large number of cross-level heterogeneous cities have appeared represented by industrial cities,mining cities and remote cities.However,the river basin has developed towards the goal of mutual promotion of capacity and coordination level.In terms of spatial pattern,there are significant spatial variation.The lower reaches are gathering place for high-level cities by virtue of multiple advantages.But the north of Anhui Province and Jiangsu Province are in the low-lying areas at the level of the basin’s resource system.The level of midstream is next to the downstream and has strong growth.However,there are still low-level clusters of environmental system in western Hubei.The upstream shows the characteristics of lowlevel agglomeration.And the link between the resource,environmental,economic and social system is broken.At the same time,the spatial heterogeneity of the social system is relatively prominent.The relationship between the space structural mode and the central cities in the three major urban agglomerations of the river basin experienced no real change.For example,the Yangtze River Delta focus on the Shanghai-Ningbo-Hefei-HangzhouNanjing development zone.Its level decreases gradually from south to north.The green development level of urban agglomeration in the Middle Reaches of the Yangtze River is dominated by the three central cities.This spatial structure is inertial and locked down.Chengyu urban agglomeration forms a spatial pattern of two belts in the east and the west relying on the development of Chengdu and Chongqing.And the central of it has been collapsing.Finally,this paper explores the limiting factors of each city and the spatial effects of the neighbourhood from the internal and external perspectives.The exploration of the limiting factors is mainly used to analyze the weak links that are main directions of the cites.The results point out that many cities in the river basin falls into double trouble: protection and development.The most typical of them are resources-based cities,like Huaibei,Nanchong and Qujing due to the the resources curse effect.There is coupling relationship between the location,regional type and the short planks in green development of cities.The limiting factors of cities with the same short plank are similar.For the cites which are dragged down by resource system,the insufficient capacity of water and forest resources is a common factor hindering the improvement of them.Spatial effect analysis is to discuss the impact of spatial elements on urban green development.The results show that the surrounding areas with higher level usually have greater influence of radiation.On the contrary,the surrounding areas with lower level usually have the inhibitory effect which will reach the maximum when there is a little difference between the two spatial units in green development level.This discovery points out the potential disadvantages that the city needs to be alert while enjoying the benefits of regional collaborative development.In addition,level evolution of the spatial units in the upstream area are weakly related to the surrounding areas,which makes it difficult to full play its driving effect.This phenomenon is the important origin cause of continuous agglomeration of low level in the upstream area.The third part is practical guidance.Based on summarizing the characteristics of the current situation and the evolution law,this paper constructs a combined prediction model to make a short-term forecast of the green development level of the river basin with the help of BP neural network,which can explore potential difficulties in the future,such as potential low-level cities and polarized cities group.Combined with the existing problems and the key influencing factors,specific coping strategies are proposed in three spatial scales—the river basin,sub-reaches and key cities.