| Ecological urban agglomeration(EUA)can be defined as a system of assembled cities in a district based on the concept of ecological development,a well-spaced ecological urban system,an ecological transportation system with compact cohesion and convenient connection,an ecological industrial system with orderly division of labor,and forming an integrated corridor network,of ecological corridors,water corridors,and cultural corridors.At present,there are some problems in the ecological development of urban agglomeration spatial structure in China,such as the fragmented ecological space,the spatial structure to be optimized,the traffic system with low network level,and the loose cooperation of industrial space.We take the spatial structure optimization of urban agglomerations as the research aim,and take Beijing-Tianjin-Hebei(BTH)urban agglomeration as the research object,to explore the spatial structure optimization path of EUA.The main studies and findings of this dissertation can be summarized as follows:(1)The composition system of EUA spatial structure was constructed through the analysis of domestic and foreign literature and classic cases.The composition system includes ecological urban system,ecological industry system,ecological transportation network system,and integrated corridor system.(2)The research paradigm of EUA spatial structure was constructed based on elevant research methods,especially the framework of geodesign.Representation models-process models-evaluation models-change models-impact models-decision models are applied to the whole process of the spatial structure study of ecological urban agglomeration,so as to establish the research paradigm of EUA spatial structure.(3)Through the analysis of evolution features and evaluation of Ecological Urbanization Level of BTH,we can see that the urban system of BTH has been generally developing towards rationalization and the ecological urbanization level of BTH has risen,but the scale structure and function structure still need to be optimized and improved.The cities were divided into five categories and seven grades by using urban population,and the composite city scale was further calculated.The basic function,advantage function and specialized sector of each city were identified by location entropy.The results showed that the trend of population agglomeration to big cities has slowed down,but there was still a significant polarization on the hierarchical scale.The regional characteristics of urban system functions were significant and the functional structure remains to be optimized.The ecological urbanization level of BTH has risen,but there were great differences among sub-factors.(4)Through the research on the industrial development characteristics of development zones and the evaluation on ecological level of the industrial structure,it was concluded that the distribution of development zone industries in BTH was significantly different,and the ecological level of industrial structure has risen.Geographical linkage rate,kernel density analysis,and principal component analysis were used in this process.The results showed that the development zone industries of BTH were concentrated in capital and technical type,and the technical development zone accounted for the largest share.The scale of labor-intensive development zones was small and the concentration degree was low.The ecological level of industrial structure fluctuated notably before 2004,and steadily improved from 2004 to 2014.After 2014,Beijing gradually formed the inverted pyramid industrial structure of“Three Two One”.(5)The distribution characteristics,accessibility of the road network and ecological traffic level in BTH were analyzed.It was concluded that the regional development of traffic networks in BTH was not balanced,but the accessibility has been improved and the ecological traffic level has developed.The accessibility of the highway network was analyzed by calculating the time cost,the accessibility of the railway network was analyzed by constructing Origin-Destination time matrix and calculating the weighted average travel time,and the ecological traffic level was evaluated though the DPSIR evaluation model.The results showed that the traffic accessibility of the plain area in the southeast of BTH was higher than that in the northwest,the large-scale construction of expressways and high-speed railways has increased accessibility to a new level,and the ecological traffic level of BTH showed U-shaped characteristics.(6)Through the analysis of land use/cover change and ecological environment benefit,we could see that the land use of BTH has changed dramatically,and the ecological environment has improved,but problems are still serious.LUCC,land transfer characteristics,and ecosystem service value evaluation were applied to this process.From2000 to 2020,the total area of farmland decreased by 10.86%,the built-up land area increased by 80%,and up to 14.81%of the whole land has undergone type transfer,of which farmland transfer accounted for 47.08%.The total value of ecosystem services in BTH has decreased by CNY 47.9 billion from 2000 to 2020,which was mainly reflected in the farmland ecosystem services.BTH is short of water resources,and per capita water resources were extremely low.Air quality has been significantly improved,but was still behind other regions in China.(7)The multi-scenario simulation and the characteristics of BTH urban expansion were conducted,and the results showed that the urban expansion efficiency of BTH was generally low and the measures of“Science and technology”+“Design”could effectively curb disorderly urban expansion.The urban expansion characteristics were analyzed by using urban expansion speed,urban expansion efficiency,and the change characteristics of built-up land.From the perspective of“Science and technology”+“Design”,four scenarios of inertial expansion,ecological expansion,urbanism expansion and ecological urbanism expansion were set up and simulated.The simulation results showed that both the application of“Science and technology”measures and“Design”measures could curb the speed of urban expansion,and the integration of“Science and technology”and“Design”can effectively curb disorderly urban expansion,so that the city could develop in a more ecological and sustainable direction.(8)The integrated ecological and cultural corridor network of BTH was constructed through the identification of ecological corridors,water corridors and cultural corridors.The results showed that the space centralization effect of ecological sources and cultural resources in BTH was significant,and the ecological corridor network was poor.RUSLE,MCR,nuclear density analysis,and accessibility analysis were used to construct the integrated corridor network by identifying ecological sources,ecological corridors,water corridors,cultural resources and cultural corridors.The area of ecological sources was18075 km~2,accounting for 7.95%of the total area of BTH,which was concentrated in the Yanshan Mountains and Taihang Mountains,and a total of 1741 cultural resources were concentrated in several cultural core areas.The ecological corridor form was relatively single,poor network and connectivity,the water corridors with good shape were fan-shaped from west to East,the distribution of cultural corridors was closely related to the natural environment,and the Great Wall cultural corridor and the Jingguang cultural corridor were basically parallel to the ecological corridor.(9)Finally,four strategies were put forward to optimize the spatial structure of BTH:to build the“multi-center group”ecological urban system,the“large clusters+small clusters”ecological industrial system,the“strong cores+smooth nodes”ecological traffic network system,and the“RGB”integrated ecological and cultural corridor network in BTH.75 figures,49 tables,and 209 references. |
PDF Full Text Request