| Since the reform and opening up,China’s rapid economic development and the continuous expansion of cities have brought threats and challenges to farmland protection,ecological environment security,and internal coordination of cities.National-level policies for urban expansion management and control have been gradually introduced,after the establishment of the Ministry of Natural Resources.《Several Opinions of the Central Committee of the Communist Party of China on Establishing a Land and Space Planning System and Supervising Implementation》were issued in May,2019,and guidance recommendations were made on land and space planning and demarcation of urban growth boundary.Some areas have made responsive attempts and exploration,but policy measures and technical methods still need to be further improved.Yubei District,Chongqing is the industrial core area of Liang-jiang New District,in recent years,the urbanization construction has been rapidly promoted,and the urban land has expanded rapidly.in Yubei District,the urban construction land has increased 66.91%in 2009-2017,but the internal land use structure in the city is not reasonable,there are some inefficient land,and the land space for new development is limited due to the topographical restrictions in the area,which affects the later development.Along with the rapid changes in urban land use structure,large amounts of arable land was developed in Yubei District,and the scale of arable land decreased 16.18%from 2009 to 2017,and the food production and ecological security are facing threats and challenges at the same time.At present,scientifically delineating the urban growth boundary of Yubei District and providing corresponding control measures have become one of the important tasks to guide the healthy development and control the urban disorderly expansion trend of Yubei District cities.Taking Yubei District of Chongqing as an example,this paper studies the urban growth boundary delineation according to the idea of fixing bureau,fixing total quantity and fixing boundary.In this paper,the reuse of inefficient land is considered in the calculation of the total scale of urban construction land,and the scale prediction method combining stock activation and incremental prediction is constructed.Firstly,the differences,advantages and disadvantages,and applicability of various types of spatial planning achievements that control urban expansion in Yubei District are compared and analyzed,and point out the necessity of rebuilding the method system of demarcating the urban growth boundary;Secondly,based on poi data of public service facilities,calculate the degree of urban sprawl,analyze the urban basic pattern,capacity and direction of urban expansion in Yubei District,and divides the study area to prepare for the later partition simulation of land use;Thirdly,combined with the comprehensive analysis of Markov model,stock identification and other planning indicators,the stock land scale and total land use scale of 2035 in Yubei District under the existing law of development are measured;Finally,the double-evaluation results were input into the FLUS-UGB model with verified accuracy,which were obtained by the artificial neural network model and a multi-regulation method.Then,simulated and predicted the spatial layout of land use in Yubei District in 2035,and based on this,the boundary of urban growth were delineated and corresponding control measures were proposed.The conclusions are as follows:(1)Analysis of the land use changes in Yubei District and the results of the existing space control planning show that the rapid urban expansion in Yubei District has led to a large amount of farmland occupied,the scale of farmland rapidly declined.The existing management planning results have their own limitations and it is difficult to effectively play a guiding and controlling role.From 2009 to 2017,Yubei District significantly interfered with land use types and scales through large-scale development and construction activities.A large amount of arable land was occupied for development,and during the period,the arable land scale decreased by 9608.75hm~2,which is the most significant change in land use type.The existing spatial management control planning results in Yubei District have difficulties in balancing the spatial form integrity and the accuracy of control function,and it is difficult to adapt to the complex and flexible situations in practical applications.(2)The research on urban sprawl measure and future development pattern in Yubei District shows that there are obvious spatial differences in urban expansion trend,and the spatial zoning can effectively reflect the spatial pattern of urban expansion.The density distribution of public service facilities can well reflect the distribution of urban spreading hot spots,it shows that the lowest spreading degree is in old city core area and the south of San-long street,while the former northern new district and Yue-lai street have moderate spreading degree,and the industrial park in the outer edge of the city shows high spreading situation.According to this study of urban sprawl pattern and the actual development of the study area,the low spread area in the south,the high spread area and the middle spread area in the middle,and the peripheral low speed development area in the north are delineated.(3)The research on the identification of the stock land in Yubei District found that the scale of the stock land is considerable and the land for public administration and public service and residential use is the main land.The area of the land available for secondary development and utilization in Yubei District is 1178.89hm~2,and the public administration and public service land is 394.28hm2,the residential land is529.68hm~2.The stock land is mainly located in the northwest of San-long Street,the southwest of the old urban areas and the central core area of the Innovation and Economic Corridor,which is the main renewal and transformation area under the target of stock planning in the future,while the new urban construction land is mainly distributed in the former northern new area and within the industrial parks,relying on the existing urban construction land to expand,which is the mainly area for new industrial distribution in the future.(4)Researching the suitability of land and space development,multiple-planning integration and simulation of land use space layout in Yubei District,and accordingly delimit the urban growth boundary for 41174.18hm2.The delineation results combine the advantages of existing spatial control planning results,and make up for their limitations,which are more suitable for practical needs.The suitability of urban construction and development in Yubei District shows a tread of the strongest in the south,the strongest in the industrial park,the weaker in the rural areas in the north and east.All kinds of protective planning achievements are mainly distributed along the three mountains,accordingly delimit the restricted conversion and the area is86186.93hm2.The change of land use transfer in Yubei District is still mainly from cultivated land to urban construction land,the area of the delimited urban growth boundary is 41174.18hm2,and the concentrated urban area is 38407.82hm2,the urban elastic development area is 2766.36hm2.This result combines the advantages of existing planning results and ensures the spatial morphological integrity and accuracy of the delineation results.This study combines the multi-specification method and the FLUS-UGB model to delineate urban growth boundary through land-use partition simulations,and takes into account the problem of low land-use efficiency that is common in domestic cities with rapid development.With the scale reduction methods by stock land identification,the forecast results are more reasonable,applicable and forward-looking,which can better guide and control future urban development. |
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