Study On The Delimitation Of Urban Growth Boundary In Jiangjin District Under The Background Of “three-line” Coordination

Since the reform and opening-up,the rapid development of the economy and the increasing urbanization rate in our country have also caused the deterioration of the ecological environment and the serious unbalance of the supply and demand of land resources in the process of rapid urbanization,which makes urbanization face a severe challenge,and the increasingly expanding urban construction land is a serious threat to the ecological and food security of the region,and the coordination of the"three-line"is a powerful measure to balance the ecological,food and urban development of the region.In view of this,this paper,based on the understanding of the problems faced by the natural environment,the social and economic environment and the urban development of the Jiangjin area,firstly coordinates the"two-wire"of the Jiangjin area through the GIS space technology.then,the suitability of the construction land in the Jiangjin region is evaluated,the urban growth rigid boundary of the Jiangjin region is defined,the scale of the population and the construction land of the Jiangjin region is predicted by the gray model and the CA-Markov model,and the urban growth elastic boundary of the Jiangjin region is determined through economic and policy guiding factors,and further obtains the"three-wire"coordination result,so as to provide reference for urban planning,ecological protection and agricultural development of the Jiangjin district.In this paper,the following conclusions are drawn:(1)Compared with the clear urban growth boundary generated by the expansion of clusters in most plain cities,the urban growth boundary in hilly areas is relatively vague.Even if combined with the experience of the predecessors and according to the special circumstances of the study area,using the scientific and reasonable comprehensive delineation method,the strong subjectivity can not be avoided.Among them,the topographical and geomorphological conditions and the broken maps for construction in the study area are the main reasons for the above results.(2)At present,most of the research on the demarcation of urban growth boundary pays more attention to ecological and farmland protection,but there is relatively little research on the implementation of“three-line”coordination.By obtaining data,this paper determines the“two-lines”as the bottom line,and strives to protect the ecological and food security of the study area to the greatest extent,and provides a reference for how to coordinate the growth boundary of hilly and mountainous towns in the context of“three-line”.(3)The delineation of urban growth boundary is usually divided into rigid boundary and elastic boundary.The method of demarcating the rigid boundary is mainly based on the evaluation method of construction land suitability based on the“two-line”coordination.The evaluation result is generally suitable.Mainly,the rigid boundary area delineated in this paper is 512.29km~2,accounting for 15.92%of the total land area in Jiangjin District.The demarcation method of elastic boundary is mainly CA-Markov model,and at the same time taking into account the land population carrying capacity and policy economic factors in the region.The elastic boundary area delineated in this paper is 187.25km~2,accounting for 5.82%of the total land area in Jiangjin District.The shape of the urban growth boundary in Jiangjin District is mainly the“X”strip,and the topography and traffic factors contribute the most to the boundary shape.(4)According to the“three-line”coordination principle,coordinating the existing ecological protection red line,permanent basic farmland and the urban growth boundary delineated by the scientific and rational comprehensive method.The coordinated rigid urban boundary area of Jiangjin District is 512.29km~2,the elastic boundary area is 187.25km~2,the ecological protection red line area remains unchanged,and the permanent basic farmland area is slightly reduced on the original basis.The final permanent basic farmland area is 99307hm~2,accounting for 30.85%of the total land area in Jiangjin District,decreased by 3348hm~2 compared with the area before coordination,and the decline ratio was only 3.26%.The impact on agricultural production activities in Jiangjin District should be small.Based on the"three-line"-based coordination background,the paper puts forward corresponding countermeasures and suggestions from the four aspects of ecological coordination,"rural and rural areas"coordination,urban planning and coordination,and expansion form coordination,so as to provide reference and reference for the sustainable development of the town of Jiangjin.