Evaluation Of Park Green Space Accessibility In Xian Based On Improved Ga2SFCA Method

With the goal of high-quality urban development in the new era,the precise construction and management has become the primary objective of urban development As the most representative public open space in cities,parks and green spaces are the embodiment of urban civilization and the spatial superimposition and mapping of urban ecological and human settlement functions.In the pursuit of urban social,ecological and economic benefits,cities have continued to promote the construction of parks and green spaces from both theoretical and practical perspectives,and a large number of high quality parks and green spaces have been built in the country.In essence,they all seek to rationalise the number,distribution and relationship between parks and urban residents in the city.This paper compares the theories of parkland and accessibility,takes the central city of Xi’an as a case study,analyses the current situation of parkland,establishes a pedestrian accessibility model,analyses the characteristics of the spatial layout of parkland in Xi’an,searches for accessibility blind spots,and proposes strategies and suggestions for the planning and construction of parkland in Xi’an.First of all,this paper reviews the concepts of park green space and the progress of research on accessibility at home and abroad,and presents a detailed interpretation and comparative analysis of accessibility evaluation methods.Field surveys and questionnaire interviews are conducted with park green spaces as the supply side and urban residents as the demand side to investigate the spatial coupling between people and parks in terms of the attractiveness of park green spaces and the travel characteristics of urban residents.A detailed analysis of the internal construction level and overall spatial distribution of park green spaces in Xi’an was conducted through satellite images,survey visits and GIS spatial analysis.Secondly,in the research example,with the main urban area of Xi’an as the evaluation target,based on park green space AOI data,population raster data and path planning data,a comprehensive service capacity evaluation system of urban park green space based on landscape environment,supporting facilities,infrastructure and park area is established through analytic hierarchy process,and the internal construction quality of park green space is integrated into the accessibility calculation model,the improved Gaussian two-step floating catchment area method was used to evaluate the accessibility of park green spaces in the central city of Xi’an.The final results of the study show that the distribution structure of park green spaces in the study area presents a "multi center patchy clustering" pattern,with an uneven overall distribution;some areas in Yanta District and Baqiao Districts have high local accessibility,while other areas have large blind areas for walking accessibility;the results of the walking accessibility assessment using 500 m as the search range are low and there is room for further optimisation.In addition to park area,the quality of park construction has a significant impact on accessibility,and while paying attention to the spatial distribution of park space,a higher level of park facilities and landscape environment should also be required.Finally,aiming at the accessibility blind spots of park green space in the main urban area of Xi’an city,a heuristic algorithm is adopted to optimize the multi-objective park green space spatial structure,combined with the distribution of population quantity,the number and site coordinates of the planned new parks are calculated to optimize the layout of park green space in the research area.After conducting a feasibility analysis on the specific location of the site through field investigation and satellite images,the types and methods of park green space construction are discussed based on practical natural environment conditions,land use status,and other factors,ultimately resulting in the specific measures of planning to build two comprehensive parks,three community parks,and five amusement parks.Based on the results of the overall analysis and evaluation,relevant optimisation strategies are proposed in four aspects: improving the transportation network,constructing park green spaces,improving park quality and building a park system,so as to provide reference advice for the construction of park green spaces in Xi’an.