Impact of spatial configuration of urban blue spaces in mitigating temperature during summer: a remote sensing and field-based observation

Abstract

Cities worldwide face heightened vulnerability to extreme heat due to rapid urbanization and the conversion of natural spaces into built-up areas. This challenge is particularly severe in the global south, where rapid urban expansion leads to the loss of green and blue spaces, essential for temperature mitigation. This study investigates how the spatial configuration of urban blue spaces affects summer temperatures, using remote sensing and field data from a rapidly growing urban agglomeration i.e., English Bazar Urban Agglomeration (EBUA) in Eastern India. The study applied ANOVA and Tukey’s HSD tests to assess temperature differences across urban core, transitional, and rural zones, comparing remote sensing and field data. Bayesian regression analyses further explore relationships between temperature and various explanatory factors, including vegetation and built-up density. Results indicate elevated land surface temperature (LST) in the urban core, reaching a peak of 63.08 °C at 80 m from blue spaces. In the transitional zone, LST shows moderate increases, from 62.21 °C at the blue space edge to 63.06 °C at 100 m. In rural areas, LST starts lower at 60.83 °C, showing minimal variation due to cooling effect of vegetation cover. ANOVA results reveal no significant variation across zones of temperature in remote sensing data (p = 0.144), possibly due to spatial averaging, while field data shows significant differences (p = 0.00045), capturing localized temperature changes. Bayesian regression highlights percentage of vegetation cover, normalized difference water index (NDWI), normalized difference built-up index (NDBI), and area of blue space as key LST predictors, with an R² of 0.875. The findings of the study on the investigation the impact of the spatial configuration of blue spaces on temperature mitigation is crucial in order to facilitate sustainable urban planning. Blue spaces that are well-designed have the potential to increase thermal comfort, enhance microclimate regulation, and reduce urban heat island (UHI) effect. This research can contribute to the development of climate-resilient strategies that promote energy-efficient urban development, public health, and biodiversity.