Spatial Accessibility Analysis Of Urban Parks In Typical Karst Area

Urban parks are important to urban residents’ physical and mental well-being,social harmony,and sustainable urban development.Constrained by landform features such as high mountains,steep slopes and little flatland,cities located in karst mountainous regions often face challenges of little land available for construction,high population density in built-up areas,and small area of park spaces per capita.With the accelerated urbanisation process in recent years,some cities have built urban parks out of natural limestone hills as a means to increase both the quantity and quality of park service provision.However,some of these parks on tower karst suffer from limited visitor capacity and low level of barrier-free access and fail to meet visitor’s basic need for recreation.Therefore,a wise design of urban park system in a karst mountain city must be built upon the analysis of such key elements as the size of the park patch,the topography of the park site,and the features of population distribution in the city.This study takes Guiyang,a typical karst mountain city as an example,based on different evaluation tools,analyze spatial accessibility of urban parks,and discusses strategies to improve urban park accessibility in karst mountain cities using the Least Cost method.The main research methods are as follows.We first set topographic coefficients,the percentage of the park space that has a gradient below 15 degrees,to indicate the topography of the park and the effective service space.The 923 urban parks in Guiyang then are categorized into“comprehensive parks” and “parks in residential areas” based on the sizes of the park patches,and “smooth parks” and “montane parks” based on their topographic coefficients.We then use different evaluation methods such as the Provide and Demand Proportion,the Least Cost method,the Cumulative Opportunity method(the Two-step Floating Catchment Area method)to measure the availability,distance,and cumulative opportunity values of park services in 2,616 residential communities,which is then used to assess the accessibility level of city parks.Thirdly we use the spatial autocorrelation analysis method to examine whether there is spatial aggregation in various types of parks,and based on different accessibility levels and different evaluation tools,to analyze what the pattern is for their spatial distribution.We have then made the following findings: First,we clarifies the core connotation of the concept of accessibility,categorize the concept from a narrow definition to a broader one,and sorts out evaluation tools,calculation methods,and geographic models of accessibility,Providing a clearer study framework for related research.Secondly,the total amount of urban parks in the study area is high,but the park patches are evidently dichotomous in terms of their areas.93.17% of the parks have an area smaller than 10 hectares and account for 10.52% of the total park area.The terrain of the majority parks is mountainous.53% of the parks have a gradient higher than 15 degrees,some of which are created completely on karst towers with limited service capacity.Thirdly,based on the Provide and Demand Proportion and the Least Cost method,the accessibility of the parks is generally good,with a good match between the park’s service area and the population distribution.The least cost of 91.89% of the communities to a park is less than 500 metres.There are differences in the accessibility level of different park types,but within a certain distance,they are still able to meet the varied needs for park services.Lastly,based on different evaluation tools,in the central part of Yunyan,Nanming,and Wudang residential areas,it is relatively convenient to all kinds of parks,but the level of per-capita Cumulative Opportunity to park services In old urban areas is relatively low,In the central part of Guanshanhu residential area however,per-capita Cumulative Opportunity is relatively high,but there are less montane parks.In addition,10% of the residential grids have high accessibility to montane parks but low accessibility to smooth parks,being difficult in accessing parks with large open space and high low level of barrier-free access in the vicinity.Those areas are hidden uncovered spots in park service provision caused by karst landform.Finally,based on the Cumulative Opportunity Per Capita method(the Two-step Floating Catchment Area method)the average level of park accessibility is high,but the spatial difference is relatively large.At the distance of 800 m,1500m and 3000 m,the proportions of residential grids with "average" and "high" accessibility level are 36.03%,48.47% and74.36%.It shows that the results of accessibility of parks differ from evaluation methods and calculation methods.It is necessary to introduce evaluation index based on the boader definition of accessibility to comprehensively evaluate the service of urban parks in karst mountain cities.The research results can provide some reference and inspiration for future studies on accessibility of karst urban parks,as well as the planning,management,and decision-making of green spaces in karst urban parks.