Investigation of cooling effects of lakes during heatwaves: A case study of Dhaka City

Abstract The increasing frequency and severity of heatwaves pose a significant threat to urban resilience by profoundly altering urban microclimates. Urban lakes have recently gained recognition for their ability to mitigate these impacts by forming water cool islands, offering localized cooling in densely populated areas due to their higher specific heat capacity. However, the influence of altered urban microclimates by heatwaves on these cooling effects remains underexplored. This study investigates how urban microclimates affect the cooling effects of diverse lakes during both heatwave and non‐heatwave periods, using Dhaka as a case study. The study was conducted using a combination of satellite imagery, meteorological data and land use information. A paired t ‐test was performed to examine the changes in cooling effects of urban lakes over a decade, while sensitivity analysis assessed parameter influences using gradient boosting regressors. The findings of the study are consistent with previous research, showing reduced cooling effects, differences in cooling intensity and distance and changes in relative humidity, wind speed and perceived temperature during heatwaves compared to non‐heawave periods. Moreover, results indicate that wind speed and perceived temperature significantly affect the cooling intensity of lakes during heatwaves, with Class III lakes (larger in size) showing the highest correlation. Wind speed shows greater sensitivity to changes in cooling distance and gradient than to cooling intensity, indicating that variations in wind speed play a crucial role in shaping the cooling characteristics of lakes. These findings provide valuable insights for optimizing urban water resources and implementing nature‐based solutions, enabling urban planners and policymakers to develop targeted strategies that enhance the cooling potential of urban lakes and improve resilience to extreme heat events.