The Research Of Urban Spatial Expansion And Regulation Based On Urban Growth Boundary

Under the background of new type of urbanization and ecological civilization construction,China 's urban spatial growth transformed from extensive urban expansion to connotative spatial growth.The connotative urban spatial growth requires to achieve scientific and efficient management,control the scale of urban development,improve the urban internal development intensity,enhance land use efficiency and protect arable land and ecological environment.Urban growth boundary(UGB)is the most commonly used growth management tool,it plays an important role in the coordination between land resource protection and urban development.The urban master planning and the integrated land use planning in China have introduced the concept of UGB,the report of the 19th National Congress of the Communist Party of China also clearly put forward to delimit cities and towns development boundary(CTDB).However,in the actual planning.CTDB is not the same as UGB,and the delineation method of CTDB was different from that of UGB.Besides,in the practical operation,the plannings usually replaced UGB with the results of control subregions,which reduced the actual utility of space growth management.Therefore,in order to improve the existing planning results,this study improved UGB delimitation method and carried out the research of urban spatial expansion and regulation based on UGB,which provided methodological and technical guidance for the efficient management of urban spatial growth and the sustainable development of cities.Ningbo is a famous port city of Yangtze River Delta,it is a start city of reform and opening-up policy,and is one of the most rapid development cities and the most vigorous economic areas in China.However,the land-oriented traditional urbanization pattern intensified the contradiction between resource constraints and economic development,which urgently needed to delimit UGB to manage urban spatial growth.This study took Ningbo City as study area.The study topic was the research of urban spatial expansion and regulation based on urban growth boundary.The research contents were as follows:(1)the dynamic analysis on current urban construction land expansion(UCLE)was implemented,the law of urban sprawl was mastered so as to guide the future urban spatial growth;(2)UGB delimitation method was established.The basis of UGB was established through land suitability evaluation(LSE);the scale and layout of UGB was determined by cellular automata(CA)model,and UGBs under multiple development scenarios were achieved;(3)a whole development pattern of economy,society,environment and resource which based on UGB was explored,as well as the regulation and management strategies of urban spatial growth were recommended.The main research results of this paper were as follows:(1)Guiding the future urban spatial growth based on the current situation of urban construction land expansion(UCLE)The expansion area of overall UCLE in the central city in the latter period was less than that in the previous period,and the expansion intensity(i.e.,equivalent to the development intensity of new construction land in a certain study period)enhanced in the latter period,it showed that the utilization of construction land was more intensive and efficient.During the study period,the directions of dominant expansion wings of the central city were north by east,east and east by south,which was biased toward the development of the port zones and surrounding areas.Industrial,traffic and residential lands were the major usages of new construction lands,commercial and public lands had less growth,and the land structure was imbalanced.The study recommended that reducing the amount of new industrial land and optimizing the structure of construction land in the future.Meanwhile,the scale and layout of new construction land in the future could be determined with the help of the average growth rates and dominant expansion wings of overall UCLE in administrative regions of Ningbo.(2)Establishing land suitability evaluation(LSE)method under the guide of ecological priority,laying a foundation for UGB delimitationThe study built LSE method under the guide of ecological priority.In the LSE process,firstly,the protection areas which were stipulated by laws and regulations(i.e.,ecological protection line area,permanent basic farmland protection area and geological disaster area)were excluded,and the protection areas were directly distributed to unsuitable area.Then construction suitability of remainder lands were evaluated and partitioned.This evaluation method not only fully connected and applied the latest achievements,but also made the evaluation more targeted,and improved the efficiency of the evaluation.Comprehensive suitability zonging results in the whole city were as follows:(1)unsuitable area(i.e.,not used as construction land):this area was divided into two parts,one part was the protection areas with an area of 3267.81km2;which accounted for 33.29%of the whole city area;another part was unsuitable construction areas which derived from LSE with an area of 380.93km2,which accounted for 3.88%of the whole city area.Unsuitable area gathered in southwest areas,southern areas of the central city,and the northern areas of Ninghai and Xiangshan;(2)basic suitable area(i.e.,not used as congregate construction land):an area of 3555.44 km2,which accounted for 36.22%of the whole city area,this area was found in parts of the northern areas,as well as the junction areas of plains and hills in middle and southern areas;(3)suitable area(i.e.,priority as construction land):an area of 2611.82 km2,which accounted for 26.61%of the whole city area,and this area mainly distributed in the middle and eastern areas of the central city,the plains of northern areas and the central city of each county/city.The results of LSE was the basic for determining the scale and layout of future urban growth,namely,the basis of UGB delimitation.We imported the LSE result into the urban growth model for urban development simulation,which could limit urban sprawl into the unsuitable area,promote optimal configuration and sustainable utilize of land resource.(3)Establishing CA model under the guide of urban development strategy,determining the scale and layout of UGBThe study established CA model of the whole city under the guide of urban development strategy,and set up three urban development scenarios based on UCLE laws of each administrative region in Ningbo,then set parameters of partition simulation and ran model repectively,which achieved the scale and layout of urban growth in 2020 and delineated UGBs.The simulated UGBs(include urban growth area inside the boundary and the boundary)would be more consistent with the multi-strategy oriented urban development needs.Meanwhile,the study improved CA model by combining LSE result,to ensure the rational utilization of land in the process of urban growth simulation.The scales and layouts of UGBs of the whole city in 2020 were as follows:(1)general development scenario:the scale of UGB(i.e.,the total area of construction land inside the boundary)was 4798.75 km2;the amount of land reserved for future urban construction was 1080.19 km2;the layout of UGB was in the middle and eastern areas of the central city,the middle and eastern areas of Yuyao City,most areas of Cixi City except the south areas,and the central city of Fenghua City,Ninghai County and Xiangshan County;(2)port development scenario:the scale of UGB was 4546.31 km2;the amount of land reserved for future urban construction was 827.75 km2;the layout of UGB was similar with the UGB under general development scenario,and there were more construction lands in the southeast coastal areas of the central city;(3)ecological priority scenario:the scale was 4231.49 km2;the amount of land reserved for future urban construction was 512.93 km2;the layout of UGB was similar with the UGBs under the previous scenarios.The study compared the simulated UGBs of the whole city with the results of control subregions in Ningbo City Master Plan(i.e.,the planned UGB).The results revealed that the UGBs under port development and ecological priority scenarios were superior to the planned UGB in the aspects of scale and spatial layout,and the UGB under ecological priority scenario was also superior to the planned UGB in the aspect of landscape pattern.Based on the above UGB comparison results in the whole city,the study optimized UGBs through adjusting UGBs in Ninghai and Xiangshan and adding greenbelt.The results of the optimized UGBs of the whole city were as follows:(1)port development scenario:the scale of UGB was 4443.82 km2;the amount of land reserved for future urban construction was 725.26 km2;the layout of UGB was similar with the unadjusted UGB,but it not included the greenbelt around the traditional urban center,and the scopes of construction lands in Ninghai and Xiangshan shrinked;(2)ecological priority scenario:the scale was 4129.34 km2;the amount of land reserved for future urban construction was 410.78 km2;the layout of UGB was similar with the UGB under the previous scenario.(4)Setting up the regulation and management strategies of urban spatial expansionBased on the results of UCLE and future development strategies of Ningbo,as well as the optimized UGBs,the study put forward regulation and management strategies of urban spatial growth:(1)first of all,industry structure and layout is the key to the urban spatial growth regulation and management.The adjustment direction of industry structure and layout of Ningbo is transforming the industry structure which dominated by industry into a new industry structure which dominated by service and industry sectors.Industry structure and layout could be optimized through expanding service industry,strengthening green leisure industry and adjusting industry layout;(2)secondly,urban comprehensive planning and management system should be established.The contents of this system are as follows:controlling the total quantity of the urban growth through establishing and perfecting the urban land supply mechanism;guiding the urban construction land growth intensity through establishing and perfecting the stock construction land management system;optimizing urban ecological environment and limiting urban sprawl through building regional greenways;(3)finally,as the basis of urban spatial growth management,UGB should be applied with the related facilities and policies in the process of implementation,and prefect implementation evaluation system of UGB and land spatial control outside UGB,in order to give full play to the actual utility of UGB.