Cooling effect and influencing factors of urban blue-green spaces based on InVEST model: A case study of Xi’an City

Investigating the cooling effects of blue-green spaces and their influencing factors is essential for optimizing urban spatial configuration and enhancing environmental resilience. Using Xi’an as a case study, this study integrates multisource data—remote sensing, evapotranspiration, and meteorological datasets—and applies the InVEST Urban Cooling Model to generate the Heat Mitigation Index (HMI) for assessing the cooling capacity of urban blue-green spaces. Landscape pattern analysis, the Geographical Detector, and boosted regression trees are further employed to reveal the mechanisms through which landscape patterns influence cooling effects. The results are as follows: 1) In summer, surface temperatures in Xi’an are dominated by moderate-temperature zones. Urban heat islands are concentrated in the central urban area and the western industrial park, with a relatively stable spatial pattern; cool islands are mainly distributed along river corridors and in suburban croplands, and appear as scattered patches within high-density built-up areas. 2) The spatial distribution of HMI is highly consistent across different cooling distances: high-value areas outside the Third Ring Road are mostly distributed along rivers or concentrated in contiguous croplands, while high-value areas inside the Third Ring Road correspond to urban parks containing water bodies; low-value areas are primarily located in high-density built-up and industrial zones, forming continuous surfaces, and appear as linear belts in surrounding rural settlements. 3) The cooling effect of blue-green spaces results from the synergistic action of multiple factors. Landscape diversity and patch fragmentation are the core driving factors, each interacting with patch size to enhance cooling capacity. All factors exhibit threshold behavior, and their influence on cooling may be either promotive or suppressive depending on the range of their values.