Mapping Thermal Hotspots in Malé, Maldives : Assessing the Relationship Between Urban Heat Islands, Climate, and Heat Risk for Sustainable Urban Planning

Abstract

This study aims to support climate-conscious urban development in greater Male’, Maldives, based on characterizations of the local microclimate. It explores intra-urban temperature variations, identifies heat risks and their factors in Male’ and Hulhumale’ phase 1 in order to support and inform climate-resilient urban strategies, driven by the absence of urban climate studies in Maldives. Measurements were primarily measured through mobile transects and fixed sensor data collection in March 2023, then analysed using Geographical Information systems. The findings indicate that intra-urban temperature patterns in the cities are influenced by, but not limited to, factors such as land use, cloud cover and wind. A noticeable urban heat island effect in the greater Male’ region became apparent as both Male’ and Hulhumale’ recorded higher nighttime temperatures compared to the nearby airport island Hulhule’. Urban heat islands are a phenomena which follows urbanization, where cities are generally warmer than their surroundings. Both cities also experienced an urban cool island effect in the early mornings, with maximum temperatures occurring later in the day compared to Hulhule’. Calmer nights were observed to be slightly cooler than windy nights, indicating a radiative cooling effect. Cloudy days and nights were observed with marginally higher daytime temperatures, suggesting a heat entrapment effect. Certain land use categories exhibited elevated temperatures compared to residential areas, highlighting the impact of land use on localized heat patterns. However, at night, impacts of land use on temperature variations appear to be low with minimal differences with consistent cooling across all types, suggesting that the influence of land use on temperature was more pronounced under solar loading. Heat Index values, a measure of perceived heat incorporating both relative humidity and air temperature, consistently indicated 'extreme caution' for both cities, underscoring an urgent need to address high outdoor humidity and its impact on human thermal comfort and well-being. Although addressing extremely high outdoor humidity presents a greater challenge than reducing air temperature, the study suggests interventions to integrate heat-resilient infrastructure and urban green infrastructure into national plans as effective approaches. Ultimately, to address the pressing question of where to best apply cooling interventions to maximize benefits in a warming climate, cities require an understanding of how the built environment impacts urban heat at a local level. Since there is no one-size-fits-all solution for urban heat mitigation, it might take a combination of customized strategies to achieve the desired result. Even with these interventions thermal discomfort may be inevitable, however the goal is to minimize risk and increase comfort as much as possible.