Integrated Identification of Hazard Impact Areas from Urban Heat and Social Vulnerability: A Case Study of Elderly and Low-Income Populations in Taipei

Against the background of climate warming and increasingly intensified extreme heat events, densely developed cities are facing ever-intensifying heat-risk challenges. In basin cities such as Taipei, restricted ventilation, complex built-environment conditions, and highly concentrated populations further exacerbate heat accumulation and retention. However, conventional meteorological station data are often insufficient to fully capture the heterogeneity of street-scale thermal environments, and they also make it difficult to identify high-risk areas where climatic hazards spatially overlap with socially vulnerable populations. Therefore, this study integrates multi-scale climate information and social vulnerability indicators to assess heat risk, with the aim of improving the local relevance of urban heat-risk identification and decision-making applications.

This study focuses on Taipei, the capital of Taiwan, to investigate the acute heat impacts faced by densely developed urban areas under a warming climate. Urban heat is not merely a meteorological outcome, but a complex microclimatic phenomenon shaped by the interaction of topographic conditions, built-environment geometry, atmospheric boundary-layer characteristics, and anthropogenic activities. To resolve the high degree of heterogeneity in urban microclimates, long-term observations with high spatial and temporal resolution are essential. This study integrates hourly air temperature data from the High-Density Street-Level Air Temperature Observation Network (HiSAN) in the Taipei metropolitan area for 2022, in situ observations from the Central Weather Administration (CWA), and the Taiwan ReAnalysis Downscaling dataset (TReAD) with a spatial resolution of 2 km. Through spatial interpolation in QGIS and ArcGIS, the study constructs comprehensive spatial models of urban heat distribution.

This study utilizes Daan Forest Park, a characteristic 'cool island' within the Taipei metropolitan area, was selected as the reference point. Monthly mean temperature differences between each observation site and the reference station were calculated to evaluate urban heat intensity, examine the relationship between built-environment characteristics and urban heat intensity, and provide a practical scientific basis for urban climate adaptation and hotspot identification. The analysis was further extended from heat-hazard assessment to risk assessment by overlaying urban heat hotspot distributions with socioeconomic vulnerability indicators, specifically targeting the distribution of older adults and low-income households, in order to identify heat-risk hotspots at different times and priority areas where high heat exposure coincides with high vulnerability. The results show that urban heat hotspots are mostly concentrated in densely built-up areas and exhibit a considerable degree of spatial overlap with areas where older adults and low-income populations are concentrated. This suggests that urban heat risk is determined not only by physical heat exposure but also closely linked to social vulnerability. Consequently,areas where high heat and high vulnerability overlap should be prioritized for subsequent urban climate adaptation and heat-risk management, and locally tailored adaptation and mitigation strategies should be proposed according to differences in built-environment characteristics and population structure across districts.