Spatio-temporal Investigation of the Urban Thermal Comfort in Khulna City and Surrounding Areas

Rapid urbanization is posing a serious threat to high-density urban areas worldwide, particularly in developing countries, with urban thermal environment degradation becoming an impending concern. Such dreadful climatic events force these cities to examine and monitor the spatial variation of the microscale thermal environment in and around the city. Our study aimed to analyze the spatiotemporal variation of urban thermal comfort in the Khulna Development Authority (KDA) area, utilizing the Urban Thermal Field Variance Index (UTFVI). The results indicate a worsening trend in urban thermal comfort, with the land surface temperature (LST) rising by approximately 4.75℃ between 2009 and 2020. During the same time, the minimum and maximum LST increased by 4.85℃ and 5.85℃, respectively, and the Urban Heat Island (UHI) increased by approximately 10%. We also found a strong positive correlation between multiple spectral indices and LST. Our analysis of the built-up area and vegetation indices showed an opposing trend, establishing a gradual decline in vegetation coverage and an increase in building footprint as the apparent causes of the temperature increase. This study's findings regarding the degradation of the thermal environment will guide policymakers to take action and implement measures to mitigate the effects. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.