Zoning effect on urban heat exposure risk: comparing four typical spatial zoning approaches

Abstract

Fully understanding the heterogeneity of heat exposure risk (HER) caused by the variability of risk components in time and space dimensions is a vital prerequisite for urban heat-related risk management, while there is not yet unequivocal quantitative evidence on the zoning effect on HER, i.e. the impact of spatial zoning approach on the spatiotemporal difference in HER. Based on township-level administrative district zone (ADZ), urban gradient zone (UGZ), local climate zone (LCZ), and land use zone (LUZ), the detailed spatial differences in HER and its 24-hour consistency were methodically explored by statistical test and coefficient quantification. The empirical analysis in Xiamen, China indicates significant global (p < 0.001) and local (p < 0.05, >87 %) interzone differences in HER under all four zoning approaches, with higher HER in urban developed ADZs, urban central UGZs, built-type LCZs, and the LUZs with more frequent anthropogenic activities. Among them, the specific interzone pattern of HER was temporally consistent only among UGZs, showing a non-linear trend of zonal mean HER with increasing distance from the urban core areas (rs ≤ −0.8956, p < 0.001). Additionally, the zoning effect on HER was emphasized by the stable greatest degree of interzone difference in HER among UGZs. In general, comprehension of the zoning effect on HER from the relevant characteristics of risk components was suggested given the significant global interzone difference in both heat hazard and outdoor exposure (p < 0.001), and detailed temporal dynamic analysis is proved to be necessary since the relevant features were not completely consistent over 24 h. These novel findings enhance the existing understanding of the zoning effect on HER and provide scientific support for the effective zoning management of city-level HER.