Study On The Method Of Delimitation Urban Growth Boundary In Jiaxian City

Urban spatial growth boundary,as one of the important technologies and control policies of urban spatial growth management,is of great significance to the sustainable development of cities.At present,the process of high-speed urbanization has led to the rapid expansion of urban construction land,which has led to the continuous encroachment of various types of ecological land,and the intensification of environmental pollution.How to balance the expansion needs of urban survival and development while ensuring the sustainable development of natural ecological land has been increasingly valued by scholars.The delineation and implementation of urban spatial growth boundary will help the transformation of urban land from extensive and extensive growth to connotation and intensive improvement,effectively solve the practical contradiction between urban expansion pressure and resource and environmental conflict,and promote the sustainable development of the city.The loess hilly-gully region in northern Shaanxi Province is one of the regions with the most fragile ecological environment in China.The urban spatial development is constrained by the topography,and the contradiction between the expansion demand and the fragile ecological environment is prominent.As an extension of the loess hilly and gully region,Jiaxian County has prominent conflicts between urban development,natural ecology,and culture.The tight constraints of resources have prompted Jiaxian to jump out of the old city area and open up new cities for development.The center city ultimately consists of "Jialu City" and "Yujia New City" two parts.This paper takes the central city of Jiaxian as the research object,based on the 2007,2012,and 2017 three phases of remote sensing images,from the qualitative and quantitative perspectives,it analyzes the characteristics of the urban land use and the development of the boundary of the built-up area,and explores the urban spatial growth.Existing problems and their influencing factors.On this basis,from the perspective of “restriction” and “growth”,GIS spatial analysis techniques and CA-Markov models were used to simulate the spatial patterns and development trend in the study area,and the rigid constraints of urban space growth were interpreted.The scale of elastic expansion,at the same time,simulates the spatial growth of the city based on the SLEUTH model,and then delimits the urban spatial growth boundary.The main conclusions are as follows:(1)The contradiction between urban development and natural ecology and cultural resources in Jialu District has intensified,and shrewd contraction is proposed;Qijia New City faces the potential conflict between urban expansion needs and ecological pressure,and it needs flexible control;(2)Using land suitability assessment and ecological sensitivity analysis methods to define inexorable "rigid" boundaries for urban spatial growth;(3)Based on the transition rules between urban land use,CA-Markov model is used to predict the scale of urban development in 2030.At the same time,the SLEUTH model is used to simulate urban spatial growth and delineate the “elastic” boundary of urban spatial growth.The study carried out research on the urban spatial growth of Jiaxian City.The comprehensive multi-technology method delineated the spatial growth boundary of urban space.It also provides reference for other ecologically vulnerable areas.