Unveiling the impact of rapid urbanization on human comfort: a remote sensing-based study in Rajshahi Division, Bangladesh

The present study unveils the environmental impacts of land cover changes upon land surface temperature (LST) in Rajshahi division, Bangladesh, focusing on human thermal comfort (HTC). Using the remote sensing techniques and ArcGIS tools, the spatiotemporal indicators including LST, Normalized Difference Water Index (NDWI), Normalized Difference Vegetation Index (NDVI), Discomfort Index (DI), and AWBGT Index were analyzed for the years 2005–2020, with Landsat 8 OLI and as well Landsat-5 TM satellite imageries. The results indicate that over 15 years, the built-up area expanded from 3469.29 km2 (21.02%) to 5872.76 km2 (35.59%). The urban area has enlarged at 0.97% per year since 2005. In 2015, maximum and minimum temperatures of the division were noted at 34.88 and 24.16 °C, when vegetation percentage was minimum compared to other study periods (22.97%). The assessed LST during the study periods showed that the south-eastern and north-eastern parts of Rajshahi division exhibited higher LST. The study uncovered a robust correlation among LST, NDVI, and NDWI. Subsequently, LST and air temperature were positively correlated and LST was found to be greater than air temperature in all periods. However, urban expansion is recognized as a prime contributor to thermal stress-related problems in the Rajshahi division. The study was observed increasing thermal discomfort over time. In 2005, about 40% experienced discomfort, dropping to 30% in 2010, but sharply rising to over 80% by 2020. These findings highlight the significant impact of urban expansion on thermal stress in the region. From human thermal comfort, it disclosed that in 2020, 48% of the study area experienced dangerous heat stress, with 30% experiencing temperatures ranging from 27.7 to 32.2 °C. Our findings appeal for sustainable urban planning to mitigate the adverse impacts of increasing LST on human health and well-being.