Spatiotemporal Analysis of Urban Heat Island Impacts on Human Thermal Comfort and Ecological Integrity in Dhaka North City Corporation (DNCC)

Dhaka, one of the fastest-growing megacities in South Asia, has been losing its important ecological buffers due to unplanned and rapid urbanization. This has intensified the Urban Heat Island (UHI) effect, which has raised the risk of heat-related discomfort and health problems and threatened the city's ecological balance. Existing studies of Dhaka's UHI are confined to surface temperature mapping and fail to link to human thermal comfort and ecological quality. This study investigates the spatiotemporal changes in UHI of Dhaka North City Corporation (DNCC) between 1994 and 2024, and forecasts the future of UHI conditions for 2034 and the impacts on human thermal comfort and ecological integrity. Land Surface Temperature (LST) was derived from Landsat images during six pre-monsoon periods and standardized by the mean standard deviation method to identify hotspots. The analysis of hotspot zones was done using land use change and the UHI stack profile of three hotspot zones (Uttara, Mirpur and Badda). The Discomfort Index was used for the evaluation of human thermal comfort and the Urban Thermal Field Variance Index (UTFVI) was used for the evaluation of ecological quality. The built-up area increased rapidly in all hotspot areas, such as Mirpur (75% to 43%) and Badda (31% to 6%). Vegetation cover and water cover almost died out in most of the hotspot areas. By 2024, 95.5% of DNCC experienced severe thermal stress (DI>29°C) compared to under 5% in 1994, with the ecological quality moving from mostly "Excellent" to "Bad" or "Worse. If the vegetation cover is not increased from the projected 11.85% to 34.5%, then the peak LST for 2034 could be raised to 49.45°C. The results indicate that, for long-term sustainability in Dhaka, rooftop greening, building incentives based on FAR and green corridor planning should be considered as priority interventions.