Study On The Delimitation Of The Development Boundary Of Small And Medium-sized Towns Based On The Combination Of"dual Environmental Evaluation" And Plus Model ——A Case Study Of Wuhe County

With the continuous development of urbanization throughout the country,the boundaries of cities are also expanding rapidly.The extensive and disorderly urban development and construction model formed over the years has also brought a series of serious urban problems,such as environmental pollution,soil and water loss,resource shortage,ecological deterioration and so on.In recent years,under the background of the government vigorously promoting the construction of ecological civilization and the new type of urbanization,the urban development boundary,as a policy tool that can effectively alleviate the contradiction between land resource development and ecological environment protection,has been widely used to guide the rational expansion of urban construction land and spatial intensive development.However,in the process of the construction of the land spatial planning system in the new era,with the demarcation of the development boundary of cities and towns around the country,the problems such as vague connotation,limited norms and single operation are gradually exposed.Therefore,there is an urgent need to explore the method system of localized urban development boundary demarcation suitable for different types,levels and regions.First of all,this paper combs the research results of urban development boundary at home and abroad,through a comprehensive analysis of the connotation of urban development boundary in different periods and different regions and the differences of demarcation methods,combined with relevant planning practice cases,summarize the shortcomings of the existing research.At the same time,the core concepts are defined,and the "urban man" theory,urban development boundary theory and ecological security protection theory are introduced in detail,which lays a theoretical foundation for the later research.Secondly,it starts from coordinating the three relationships of supply and demand,rigidity and elasticity,development and protection of urban development.Taking Wuhe County as an empirical case,based on the situation of land use development for many years,based on the results of "double evaluation" analysis,combined with the development characteristics and driving factors of small and medium-sized towns,through the analysis of the current situation of urban construction,the analysis of development trend and the prediction of land use scale,the land use change analysis software is used to simulate the spatial evolution and comprehensively formulate the urban development boundary according to the requirements of policy and planning.Finally,according to the land space suitability evaluation,we comprehensively judged the distribution of three types of space in Wuhe County and delineated the development boundary of rigid cities and towns,with a total area of 93474.54 hectares,accounting for 65.45% of the total scale of the study area.Based on the current situation and characteristics of cities and towns,the development driving factor system of Wuhe County is constructed,combined with the evaluation of resources and environment carrying capacity and Markvo model to predict the amount of land use change in 2035 under different development scenarios.At the same time,PLUS model simulation analysis is carried out.On this basis,the development boundary of elastic cities and towns in Wuhe County is delineated,with a total area of 6859 hectares.Among them,the land scale of the urban centralized construction area is 5556 hectares,accounting for 81% of the total elastic boundary area.This paper adopts a variety of technical means and spatial analysis methods,combines the results of "double evaluation" with PLUS model,and according to the research results of urban development status,trend and spatial evolution,jointly delineates the urban development boundary system suitable for the future urban development trend of Wuhe County,and tries to provide certain reference significance and reference value for the spatial development strategies and boundary demarcation methods of other small and medium-sized towns of the same type.Figure [50] table [24] reference [116]...