Work

Installation of pocket parks in mountainous cities: A case study on the nonlinear effect of the built environment on pocket park vitality in Chongqing, China

Year: 2025

Type: article

Abstract: • Built environment factors that affect pocket park vitality in mountainous cities have been analyzed. • Sky view factors were key factors influencing pocket park vitality in mountainous cities. • XGBoost-SHAP were used to reveal the nonlinear effect of built environment on pocket park vitality in mountainous cities. • Management strategies for the configuration of pocket parks in mountainous cities were proposed. Pocket parks are regarded as valuable tools for providing green activity spaces for citizens in high-density mountainous cities. However, existing research on the pocket park vitality has hardly paid attention to mountainous cities. Due to the unique topographical conditions of mountainous cities, the built environment factors influencing the pocket parks vitality may be more complex, new indicators such as sky view factors, average slope and building enclosure have been taken into account. This study takes Chongqing as a case study of a mountainous city. It utilizes location-based service data to measure pocket park vitality. An interpretable machine learning model that integrates eXtreme Gradient Boosting (XGBoost) and Shapley Additive exPlanations (SHAP) is employed to explore the nonlinear effects and interactions of built environment factors on pocket park vitality. Results indicate that: (1) Sky view factors and residential population are significant factors affecting pocket park vitality in mountainous cities. (2) Different built environment elements in mountainous cities have optimal threshold effects on pocket park vitality. For example, optimal park areas of less than 0.08 ha, vegetation coverage rates below 0.57 are built environment intervals that can significantly enhance pocket park vitality. (3) The spatial distribution map of SHAP values and the interaction analysis reveal the spatial effects and interrelationships of built environment factors. For example, the interaction between Residential Population and Floor Area Ratio exemplifies the complex mechanism of the synergistic impact of multiple factors. We further explain specific pocket parks in combination with local contributions and put forward precise optimization strategies based on the park attributes and characteristics of the surrounding environment.

Source: Ecological Indicators

DOI: 10.1016/j.ecolind.2025.113417