Study On Spatial-temporal Evolution And Pattern Optimization Of Rural Settlements In Yanchi County

As an important carrier of human activities in rural areas,rural settlement optimizes itself gradually in the process of long-term coexistence with the surrounding environment in order to adapt to human development.In the underdeveloped northwest areas accompanied by habitat fragile environment,rural settlements' continuing to proliferate like "all over the sky star" in the geographical space,not only exacerbates the degradation of land,but also adds difficulty to the allocation of rural infrastructure,meanwhile,the rural settlements are suffering a serious blow from urbanization,resulting in the rural settlements' development completely into a disorderly state.It is an urgent problem to be solved in rural settlements in northwest China on how to seek a sustainable and suitable development mode under the background of promoting urbanization and speeding up urban and rural areas as a whole.To address these,we selected Yanchi County of Ningxia Province as a case,the trajectory of rural settlements in Yanchi County in the past 20 years was dynamically tracked based on the years of 1995,2000,2007 and 2014.The study conducted the analysis according to the process framework of "dynamic process-mode mining-driving mechanism-optimization regulation",depicted the evolution process by geo-spatial analysis and spatial measurement model,and abstracted and summarized the evolution pattern of rural settlements,also further explored the inner mechanism,finally,we seeked out the appropriate settlement layout optimization and control model of Yanchi County.The results suggest that:(1)The scale of rural settlements in Yanchi County showed the characteristics of "decentralized layout,small scale and regularity",every development stage showed a coexistence of reduction and expansion.From 1995 to 2014,the spatial distribution of rural settlements was clustered,appearing the characteristics of "north intensive and south sparse,township cluster around".The single isolated settlement occupied the largest proportion on each 2 km×2 km grid.The overall development status of the settlement was the majority of the extinction type and the new type.The evolutionary "PU" of the settlement showed that the focus of the conversion of the dominant land in the range of the dynamic changes of different settlements was around the cultivated land,grassland and forest land.And in the process of settlement optimization,there were 129 settlements continued to retain so far during the 20 years,which was the focus of the future settlement pattern optimization.(2)Based on the analysis of the comprehensive development process of rural settlement system and its spatial external form,four evolution modes were summarized as follows:driven by irrigation area along the Yellow river model,new immigration village model,new district expansion mode and self-organization development model.According to the relative position relationship between plots and surrounding areas,four kinds of plaque layout patterns were extracted,including the whole tillage surrounded type,the whole grass surrounded type,the grass-tillage-shrubbery surrounded type and the direct sand adjacent type,and further was divided into 14 subcategories.In the process of long-term coexistence with the surrounding land,the settlement of direct sand adjacent type decreased significantly.The diversified evolution path of the overall settlement in Yanchi County was further generalized,which was divided into three modes:poly nuclear type,convergent type and enclave type.The overall rural settlement development performance for the livable geographical point and the whole living environment gradually improved.(3)The spatial differentiation of rural settlements in Yanchi County was comprehensively influenced by geographical spatial factors and socioeconomic factors.The results of geographical detector showed that the influence of location condition was the most significant,mainly showed as traffic accessibility,irrigation convenience,distance from industrial park,distance from sand source,urban proximity.Be limited by the data source and the economic development of the study area,the influence of social and economic level indicators on the layout of rural settlement was not significant.We analyzed the driving process which represent the spatial-temporal evolution of rural settlement from four aspects,including drive generation,transmission,formation and feedback,each link is interrelated and restricted,which ultimately lead to the formation of clustering agglomeration development or empty abolished state.(4)The evaluation index system of geographical special dominance was constructed considering the characteristics of the evolution of rural settlement,the natural environment,the resource endowment and the location advantages,which is divided into ?,?,? and ? grades,corresponding to the development area,retention area,guide area and demolition area.The paper divided five kinds of optimization and control modes,such as key construction type,internal tapping type,radiation guidance type,characteristic tourism type and ecological relocation,and also used Voronoi model to guide the direction of settlement relocation.Finally,we put forward requirements for the scientific,suitability and sustainability on the future settlement optimization reconstruction practice,such as correctly guiding the value orientation of rural settlements,nurturing "new farmers",looking for the appropriate gathering"degree" and guide the top design of rural settlement space.The above results mapped synthetically the past,present and future of Yanchi County's rural settlement,under the background of rapid urbanization during the transition period of China,as a typical "miniature" of the northwest underdeveloped areas,Yanchi County is experiencing spatial development with both re-organization under man-made regulation and spontaneous organizational model.By optimizing the reconstruction path of rural settlement,we we can effectively improve the quality of settlement space and improve the living environment of the sandy area,and also we can guide the evolution direction subjectively by planning the preset and process control.The study enriches the content and level of rural settlement geographical theory,it is of great practical significance to promote the sustainable development of rural settlements in the sand area and can also provide a demonstration for the optimal development of rural settlements in other northwest China.