Heatwave vulnerability of large metropolitans in Bangladesh: an evaluation

Heatwaves pose a significant risk to human society. Vulnerability to heatwaves is difficult to assess since it depends on a variety of factors, particularly at the local scale. This study aimed at evaluating the heatwave vulnerability of the five major cities of Bangladesh: Chittagong, Dhaka, Khulna, Rajshahi, and Sylhet. A heatwave vulnerability index (HVI) was defined as a function of exposure, sensitivity, and adaptive capacity. Timeseries Moderate Resolution Imaging Spectroradiometer land surface temperature data for 2000–2019 was utilized. The HVI was calculated using a principal component analysis method. The findings of this study indicated that urban centers with a large proportion of built-up areas were more exposed to urban heat than their surroundings. The mean annual LST was highest in Dhaka, the capital, and lowest in Sylhet. Rajshahi and Sylhet had the largest percentage of heat-exposed and sensitive areas, respectively. Sylhet had the highest percentage of heat-vulnerable areas (63%) whereas Dhaka had the highest number of vulnerable people (12.5 million). Increasing urban green and blue infrastructures may help to lessen the negative effects of heatwaves. The methodology and findings of the study could serve as a blueprint for developing heatwave adaptation strategies in Bangladesh, and elsewhere.