Research On The Delimitation Of Urban Development Boundaries Under The Constraints Of Ecological Security And Agricultural Security

Since the reform and opening up,the scope of urban construction has expanded rapidly,and the level of social and economic development has improved significantly,however,the rapid expansion and extensive development of urban construction land bring about the low efficiency of land use and imbalance of land supply and demand.The aggravation of the contradiction between human and land is a serious threat to the national food production security and ecological security,which is contrary to the concept of sustainable development.As one of the important tasks of territorial space planning,the delimitation of urban development boundary serves the territorial space planning,and can play the role of guiding and restricting the development of cities and towns during the planning period,thus controlling the spread of cities and towns in disorder,objective of intensive and efficient development and protection of agricultural and ecological security within borders.In the context of the overall development of the construction of five-level and three-type systems for territorial space planning,the development needs of cities and towns should be rationally combined with constraints on agricultural and ecological security,objective and comprehensive simulation of the future urban spatial expansion of the dynamic changes in time and space,delineating a reasonable urban development boundary is an urgent problem to be solved.This paper attempts to take Panlong District as an example to study the delimitation of urban development boundary under the constraints of ecological security and agricultural security.Based on the geographic information atlas,the intensity of urban construction expansion and the change of landscape pattern,this study analyzed the current situation of land use and urban construction expansion in Panlong District,based on the study of the present situation of land use and the mechanism of urban spatial expansion in Panlong District,a method of demarcation of urban development boundary under the constraints of ecological security and agricultural security is proposed.Under the constraints of ecological security and agricultural security,the main solutions are:the selection of driving factors,the integration of ecological security and agricultural security,the simulation of urban expansion and the delimitation of boundaries.Based on the literature and previous research,the paper selected the driving factors and selected them by random forest as the driving factors of urban construction land expansion The evaluation of ecological security space and agricultural security space in the study area is analyzed by using InVEST model,land ecological sensitivity evaluation system and agricultural spatial suitability evaluation,and the spatial analysis is used to coordinate the space of ecological security and agricultural security,the scope of integrated constrained urban space,the urban space of Panlong District in 2030 is simulated by using Markov chain model,and the urban development boundary is delineated by using the us-flugb model based on the integrated constrained urban space,the development boundary is corrected according to the relevant planning in Panlong District.In the study,both agricultural security and ecological security were taken as conditions to restrict urban expansion,and the importance of food security and ecological security was fully taken into account,it is also more reasonable to select the driving factors of random forest selection,use FLUS-UGB to expand urban space and demarcate urban boundary.Under the restriction of ecological space and agricultural space,FLUS model is used to simulate and determine the urban space area of Panlong District in 2050 is 174.71 km~2,UGB model is used to extract the urban development boundary,and the area within the urban development boundary is 126.33km~2.The conclusions are as follows:(1)random forest is an effective tool for selecting driving factors with high precision,and the set of driving factors can reflect the economic and social development in the study area,(2)the construction of ecological security space and agricultural security space will help to ensure the ecological service function provided by ecological land and the safety of agricultural production,(3)FLUS-UGB model is used to simulate the urban expansion space based on the constraints of ecological security and agricultural security,and the simulation precision is high,it conforms to the law of urban expansion in Panlong District and provides an important reference for future urban development in Panlong District.