Investigating the cooling effects of land cover and landscape patterns surrounding rivers: Insights from the subtropical city of Changsha, China

Water bodies and green infrastructure are vital in regulating regional climate, and enhancing their cooling effect is a significant strategy for mitigating urban heat islands (UHIs). In this study, the Xiangjiang River (XJR), Liuyang River (LYR), and Weishui River (WSR) in Changsha were selected to investigate the cooling effects of land cover and landscape patterns surrounding the rivers. The results showed that the cooling effect of the LYR was the greatest, and the XJR contributed the most to UHI mitigation. In 2018, the cooling intensities of the LYR, XJR, and WSR were 8.01 °C, 7.35 °C, and 2.79 °C, respectively. The land cover landscape contribution indices of the XJR, LYR, and WSR were −1.484, −0.896, and −0.626, respectively. The contribution of fine-textured vegetation (FV) around the XJR to alleviating the UHI effect was the greatest (−0.76), and the cooling effect within a range of 200 m was optimal. The largest patch indices of FV, impervious surface (IS), and bare land (BL) exhibited strong correlations with river cooling intensity, with coefficients of 0.828, −0.523, and −0.585, respectively. Rivers notably affect extensive-interconnected IS and BL cooling but minimally impact single-aggregated FV. Our findings offer insights for optimizing the urban blue–green space distribution to alleviate UHIs.