The assessment of cooling capacity of blue-green spaces in rapidly developing cities: A case study of Tianjin's central urban area

Abstract

In rapidly developing cities, in addition to the overall change of the climatic background, the fragmented blue-green space and the expanding impervious surface may gradually become the main factors for the deterioration of the thermal environment. The effect of urban blue-green spatial characteristics on cooling cities has been fully explored in existing studies. However, only some studies have analyzed the correlation between urban blue-green spatial characteristics and different types of cooling capacity in rapidly developing cities. In this paper, the cooling capacity in plaque and municipal scale in the existing research is mapped to the neighbourhood scale and the absolute cooling capacity and relative cooling capacity of the blue-green space are estimated in the central urban area of Tianjin during the rapid development of 2001∼2021. At the same time, correlation and random forest analysis were used to quantify the influence of blue-green spatial characteristics on the cooling capacity. The results show that: 1) The cooling capacity of blue-green space in rapidly developing cities has obvious phased characteristics. 2) The explanatory ability of UBGS features for the overall cool environment of the city is relatively stable in the rapid development process. In contrast, the explanatory ability for the cooling ability of the surrounding environment shows a yearly decline. 3) The relative importance of different influencing factors on the cooling capacity of UBGS is reflected as compositional features>configuration features>blue-green spatial relationship, and the other factors have a large difference in the performance of other indicators in different years. These results can further improve the cooling capacity of urban blue-green spaces. For rapidly developing cities with intensified fragmentation, the classification of cooling capacity in limited space is significant for improving the city's overall thermal comfort.