Objective The rapid pace of global urbanization has contributed to regional economic growth while simultaneously exacerbating various urban challenges. Urban green spaces (UGS) encompass a range of vegetated zones within urban areas, serving purposes such as greening, recreation, ecological conservation, and environmental enhancement. In a broader sense, UGS includes not only green zones but also rivers, water bodies, farmlands, gardens, forests, and other undeveloped lands. The unequal distribution of urban blue-green resources is a prevalent issue in many cities. Environmental justice, a comprehensive concept, entails the equitable distribution of resources between people and the environment. Whether residents incur significant costs to access urban natural resources and whether they have equal rights to such access are critical criteria for fairness evaluation. The two-step floating catchment area (2SFCA) method is a widely used spatial accessibility metric for evaluating the fairness of urban natural resource allocation. However, the traditional 2SFCA method often overlooks people’s travel preferences and the delineation of life circles. As a result, the accessibility evaluation is typically limited to a supply-demand perspective. In addition to the disparities in resource allocation, factors related to the built environment within communities must also be considered. Promoting a balanced spatial distribution of UGS is recognized as a critical strategy for addressing the issue of insufficient urban natural resources.

Methods This research enhances the traditional two-step floating catchment area (2SFCA) method by integrating community attributes, blue-green space, and data on urban road network. Two key improvements are introduced: Incorporation of a distance decay threshold based on Gaussian equation and establishment of a 30-minute road network catchment area boundary. Three accessibility analysis methods — nearest distance method, buffer zone method, and network analysis method — are compared with the improved 2SFCA method. Additionally, based on the data on the age of community buildings, the distribution of urban green space resources is classified into four categories — “insufficient supply − aging buildings”, “insufficient supply − newer buildings”, “sufficient supply − aging buildings”, and “sufficient supply − newer buildings” — through the K-means clustering method. The classification results are visualized, and targeted recommendations are proposed for decision-makers. This research evaluates and visualizes the allocation of blue-green space resources and the clustering results for 1,025 communities within the central urban area of Wuhan. Based on these findings, tailored suggestions are provided for reference by decision-makers to guide future improvements.

Results 1) The accessibility results obtained by the nearest distance method, the buffer zone method, and the network analysis method overestimate the distribution of urban green space resources in Wuhan. In contrast, the 2SFCA method more accurately reflects the imbalance in green space distribution. 2) The inequality in the allocation of urban green spaces displays significant spatial effects, with accessibility to greenery and water bodies increasing from the city center to the periphery, showing patterns of spatial clustering. More than half of the communities have lower-than-average accessibility to urban green spaces, and substantial differences in the supply-demand ratios of blue-green space exist across different regions. The integrated design and development of waterfront spaces can help mitigate the inequality in urban green space allocation to some extent, although excessively large water bodies can negatively impact the accessibility of green space. 3) The spatial distribution of communities across different categories is correlated with the urban development patterns. For aging communities with insufficient supply, a “squeeze-in” strategy to expand urban green space is recommended. For newer communities with insufficient supply, constructing pocket parks and removing barriers to park access are proposed. For aging communities with sufficient supply, landscape design that incorporates regional characteristics is suggested. For newer communities with sufficient supply, the planning of large parks and the strategic development of transportation routes are advised. Government-led initiatives to improve the quality of urban green space, along with policies aimed at enhancing residents’ mobility, can help alleviate green space inequality.

Conclusion This research confirms the effectiveness of the improved 2SFCA method, which incorporates the daily travel behaviors of community residents, contributing to a more accurate representation of urban green space accessibility. The clustering results reveal a correlation between imbalances in urban green space distribution and urban development patterns, highlighting the importance of improving quality, providing policy guidance, and integrating regional culture to promote equity in green space allocation. In the context of urban renewal and transformation of aging communities, these findings may offer valuable insights for urban planners and researchers in the development of sustainable urban ecosystems.