Analysis of urban wetland park cooling effects and their potential influence factors: Evidence from 477 urban wetland parks in China

Abstract

Urban wetland parks can lower surrounding temperatures efficiently and play a critical role in mitigating extreme urban high-temperature weather. Understanding the urban wetland park cooling effects and their potential influence factors is necessary for the management plan of urban parks. This study first crawled 477 urban wetland parks from the Baidu Map and classified the urban wetland parks into river-based and lake-based urban wetland parks based on the distance to rivers. Then, this study investigated the urban wetland park cooling effects during the warm (April–September) and cold (January–March, and October–December) seasons based on the largest cooling distance (LCD), the largest cooling intensity (LCI), the random forest (RF) and the partial least squares (PLS) regression models, and Spearman’s correlation coefficient. The results show that: (1) Both river-based and lake-based urban wetland parks exhibit a stronger cooling effect during the warm season. Lake-based urban wetland parks have a higher LCI; however, river-based parks have a higher LCD. (2) The RF model outperforms the PLS model in modeling the relationship between LCI and the potential influence factors, with a 5.68% increase in average RMSE and a 20.64% increase in R2.(3) The water cover fraction inside urban wetland parks is the most influential factor. There is a strong similarity in the relative importance of potential influence factors to river-based and lake-based urban wetland parks. The study indicates a new park should be located with priority in regions with more impervious layers, for example, the high-density building areas. Besides, a new park should limit the proportion of impervious layers to less than 13% and ensure the proportion of water bodies is at 70% at least to obtain a stronger cooling effect. Our study reinforces the understanding of urban wetland park cooling effects and has critical implications for better management plan of urban parks to mitigate the urban heat problem.