Research On The Delineation Of Urban Growth Boundary In Wuhan Metropolitan Area Based On The Simulation Of Spatial Structure Evolution

As an important spatial unit of emerging urbanization,the metropolitan area has gradually become a new form of spatial governance and a new driver of economic growth.Factors such as population growth,urban expansion,and socio-economic activities influence the evolution of spatial structure during the formation and development of metropolitan areas and affect the rational use and development of territorial Space.As an essential strategy of the territorial spatial planning system,the urban growth boundary(UGB)has an irreplaceable role in safeguarding ecological security and controlling urban expansion.However,most studies on UGBs in China focus on individual cities but less on urban growth boundary delineation in metropolitan areas based on spatial structure orientation.Similarly,most of the studies focus on exploring and applying the delineation methods and less on evaluating the benefits of UGB delineation.In the context of rapidly promoting the development of urban clusters and metropolitan areas in China,how to delineate the UGB of metropolitan areas based on the perspective of spatial structure of metropolitan areas,taking into account ecological security,food security and orderly urban expansion,has become an urgent issue to be solved at present.In this context,this paper takes Wuhan Metropolitan Area(WHMA)as the study area,takes the“anti-planning”theory and the theory of smart urban growth as the principles,and uses multi-source spatial data as the basis to analyze the spatial structure evolution characteristics of WHMA from 2000 to 2020,and uses the spatial structure of mature metropolitan areas at home and abroad as the reference to set the spatial structure scenario of WHMA development in 2030.Second,based on the analysis of land-use changes in the last two decades,this paper predicts the land use pattern of the WHMA in 2030 under different spatial structures by constructing a coupled Markov-PLUS model,and we delineate the UGB under different structures based on the expansion-erosion algorithm.Subsequently,we quantified the benefits of UGB delineation using the UDES constructed in this paper.Finally,based on the delineation evaluation results,we select the optimal UGB delineation scheme and spatial structure of the WHMA in 2030.After that,we propose future management strategies and recommendations for the WHMA.The main conclusions of this paper are as follows.(1)From 2000 to 2020,the monocentric spatial structure of the WHMA gradually slows down,but its primacy is still as high as three and above,indicating that the WHMA still shows an uneven development.Referring to the spatial structure evolution of mature metropolitan areas,that is,from strong monocenter to solid polyester,this paper sets five spatial structure scenarios of the WHMA in 2030 as solid monocenter scenario(q=1.20),weak monocenter scenario(q=1.10),weaker monocenter scenario(q=1.08),soft polyester scenario(q=0.90)and strong polyester scenario(q=0.75).(2)Influenced by urbanization,the construction land area of the WHMA increased by2339.17 km~2.The arable land area decreased by 2453.71 km~2,the grassland area,wetland area,and water area continued to increase,and the forest land area continued to decrease from 2000 to 2020.The accuracy of the land use pattern of the WHMA in 2020 simulated by the Markov-PLUS coupled model is high(the Kappa coefficient is as high as 0.92),and this result indicates that the Markov-PLUS coupled model constructed in this paper applies to the simulation of future land-use changes in WHMA,which provides essential support for subsequent studies.(3)The maximum UGB area of the WHMA in 2030 under different spatial structures is 3956.54 km~2,and the minimum is 3841.94 km~2.The UGB delineated by the WHMA breaks through the constraints of administrative boundaries,and the UGBs of different cities in the metropolitan area are mostly spatially characterized by the distribution of“one main area and multiple central clusters”.The UGB of WHMA under monocentric and polycentric structures differ significantly in terms of area and morphology.Under the monocentric structure,Wuhan and Huanggang have a significant expansion of their UGB patterns.The main area of the UGB is larger than the polycentric scenario and has a more significant number of central clusters.Under the polycentric structure,the UGB of Ezhou,Xianning,Tianmen,and Qianjiang covers a broader area than the monocentric scenario.The central area of the UGB extends and expands to the neighboring areas.Also,the area and number of central clusters are significantly increased.(4)Among the various spatial structure scenarios of metropolitan areas,Under the strong polyester structure(q=0.75),the UGB of the WHMA delineated has the best delineation benefits.It maximizes UGB delineation’s ecological,economic,and social benefits.The monocentric spatial structure cannot effectively play the policy effect of the UGB of WHMA.In the following study,we can start from two aspects:“promoting the integrated and balanced development of the region and building a polycentric WHMA”and“optimizing the spatial structure and territorial spatial layout by playing the role of UGB control”,aiming at shaping the polycentric spatial structure of WHMA and realizing the UGB control effect.