Harnessing Urban Cool Island: Efficacy of Urban Ponds for Mitigating Heat in Old Dhaka Neighborhood

Abstract

Dhaka, a rapidly growing megacity, experiences severe Urban Heat Island (UHI) effects due to dense urbanization, limited green spaces, and impervious surfaces. Nevertheless, several regions of Old Dhaka exhibit Urban Cool Island (UCI) characteristics, predominantly shaped by the presence of urban water bodies. This study identifies a key research gap in understanding how different LCZ morphologies influence the cooling performance of urban ponds in the old Dhaka neighborhood. The thermal cooling effects of two urban ponds, WAPDA and Azimpur Colony Pond, located within two distinct Local Climate Zones (LCZs), have been investigated as case studies. Using a combination of satellite-derived Land Surface Temperature (LST) data from Landsat 8, empirical microclimatic tracking, and comparative spatial analysis, the study assessed temperature, humidity, wind flow, and cooling performance. Findings reveal that surface area, edge vegetation, and surrounding urban morphology significantly influence thermal resiliency. While the WAPDA Pond, with a larger surface area and vegetated edge, showed a 2.1°C lower edge temperature, its cooling efficiency was limited by its dense surroundings. In contrast, the Azimpur Pond, located in a more open urban layout, achieved higher UCI intensity with only a 0.66°C temperature rise within 100 meters. This preliminary study suggests that Canyon Aspect Ratio (H/W), Sky View Factor, and vegetation coverage are critical in determining UCI effectiveness in dry winter conditions. Future urban planning strategies in Old Dhaka could consider prioritizing preserving urban ponds, increasing greenery, and optimizing street canyon configurations, but further multi-seasonal investigation is needed to validate these benefits across diverse climatic conditions. The studies provide initial insights into the spatial interplay among urban density, openness, and waterbody mediated microclimate regulation in the compact tropical climate of old Dhaka. These interventions may improve thermal comfort, reduce energy demand, and support thermal resilience in rapidly urbanizing tropical cities, though broader validation is required before generalizing these findings.