Assessing Spatial Accessibility to Hierarchical Urban Parks by Multi-Types of Travel Distance in Shenzhen, China

Abstract

Urban green spaces play a critical role in public health and human wellbeing for urban residents. Due to the uneven spatial distribution of urban green spaces in most of cities, the issue of the disparity between supply and demand has aroused public concern. In a case of Shenzhen, a modified Gaussian-based two-step floating catchment area (2SFCA) method is adopted to evaluate the disparity between park provision and the demanders in terms of accessibility at hierarchical levels under four types of distance (e.g., Euclidean distance, walking distance, bicycling distance, and driving distance), which is well aligned with hierarchical systems in urban green spaces in urban planning practice. By contrast and correlation analysis, among the four types of distance, the statistical correlations are relatively high between Euclidean distance and the other three. Nonetheless, the pattern of spatial accessibility under different type of travel distance is apparently variant. Accessibility calculated by Euclidean distance is overestimated relative to that of the other three, while the pattern of walking distance and bicycling distance is similar to each other. The choice of type of distance is worthy of caution when evaluating spatial accessibility by 2SFCA method. Results show that the accessibility to parks at all hierarchical levels is high particularly, particularly at the natural level. However, the disparity between the supply and demand is significant. The percentage of communities that have high population density but low park accessibility is over 40% (equivalent to approximately 55% of the population). The finding may provide implications on access to urban greens paces for urban planners and authorities to develop effective planning strategies.

The Spatial Optimization and Evaluation of the Economic, Ecological, and Social Value of Urban Green Space in Shenzhen

“…Eight types of land use in Shenzhen were identified: cropland, forest, grassland, shrubland, wetland, water, impervious surface, and bareland. Urban public green space includes parks and reserves, sporting fields, riparian areas such as streams and river banks, greenways and trails, community gardens, street trees, and nature conservation areas, as well as less conventional spaces such as green walls, green alleyways, and cemeteries [45]. In this study, UGS is defined as parks, wetlands, grasslands, and forests in Shenzhen.…”

“…Within this context, local governments have made efforts to preserve UGS and have developed many urban parks in Shenzhen. Shenzhen was the first city in China to win the award for livable communities in 2000 [45].…”

Evaluating Spatial Disparity of Access to Public Parks in Gated and Open Communities with an Improved G2SFCA Model

“…The G2SFCA model, which was first proposed by Dai [30] and later used by many researchers to evaluate park accessibility [33][34][35]44,45], is an extension of the traditional model [31] that modifies the distance-decay function based on a threshold travel time. The method is implemented using a two-step procedure.…”

“…To implement the improved 2SFCA model, the supply and demand point data of the study area were inputted, and travel time was calculated using the network distance based on the actual roads in the network. The analysis module of the ArcGIS 10.5 platform was used instead of the Euclidean distance, the latter of which overestimates park accessibility because it considers only straight-line distances [45]. For supply points, geometric centroids of neighborhood parks and regional parks were utilized to represent the parks.…”

“…Most park accessibility studies on urban parks have used the 2SFCA method to evaluate supply capacity; these studies consider only park sizes [33,44,45,51]. Size is absolutely critical because, compared with a small neighborhood park, a large city park may provide more functions and thus promote more planned physical activity [49].…”