Optimizing local climate zones to mitigate urban heat island effect in human settlements

Rapid urbanization has caused radical changes in urban climates. As a result, issues related to urban thermal environments have become more prominent. Finding a balance between urban expansion and thermal environment quality is key to ensuring sustainable urban development. Taking Dalian City (China) as an example, we used multi-source datasets, including Luojia1-01 nighttime light imagery, Landsat-8, Sentinel-2, and building vector data, to analyze the thermal characteristics of different local climate zones (LCZs). Additionally, the LCZ combination mode with the lowest heat island effect intensity in the human settlements was also investigated. The results showed that the human settlements covered an area of 351.976 km2, with 33.476% corresponding to building LCZs (LCZ1-10) and 66.524% to natural LCZs (LCZA-G). The different LCZs had different thermal environment characteristics, and the UHIA values for the building LCZs were significantly higher than those of the natural LCZs. Additionally, for the building LCZs, the UHIA values for compact building LCZs (LCZ 1–3) were also significantly higher than those for open and spare building LCZs. With the current settlement area and population size, the most appropriate LCZ layout model for the study area was LCZ5 + LCZ6 + (LCZ7+LCZ8+LCZA + LCZC + LCZD + LCZE + LCZG), which had areas 28.585, 57.170, 57.170, 28.585, 54.236, 54.236, and 54.236 km2, respectively. This layout model had the smallest UHIA value (11.654 °C), and urban planning according to the above ratio can alleviate the UHI effect in different cities.