Assessing the Impact of Green Infrastructure on Urban Heat Island Mitigation

Thesis Abstract

Urban areas are increasingly experiencing elevated temperatures due to the intensification of urban heat island (UHI) effects, which exacerbate energy consumption, threaten public health, and diminish urban livability. The integration of green infrastructure (GI), such as green roofs, urban forests, and vegetated corridors, has been proposed as a sustainable strategy to mitigate UHI effects; however, empirical evidence on its effectiveness across diverse urban contexts remains limited. This study aims to quantitatively assess the impact of green infrastructure on UHI mitigation within a metropolitan setting, with specific objectives of measuring surface and air temperature differentials in areas with varying levels of GI development, identifying the key types of GI most effective in temperature reduction, and examining spatial and temporal variations in UHI intensity attributable to GI. The research adopts a mixed-methods approach anchored in an observational cross-sectional design. The primary data collection involves satellite-derived thermal imagery and ground-based temperature measurements taken across 50 sampling sites within the city, selected using stratified random sampling to ensure representation of different land cover types and green infrastructure densities. The sample includes 30 sites characterized by high GI presence and 20 sites with minimal or no GI. Surveys and structured interviews with city planners and residents supplement primary data, providing contextual insights. Data collection instruments include remote sensing software (e.g., ENVI), infrared thermometers, and structured questionnaires. To examine the relationship between green infrastructure and temperature reduction, multiple regression analysis and spatial analysis techniques such as Geographically Weighted Regression (GWR) are employed, supported by descriptive statistics and ANOVA for comparative analysis. The theoretical framework integrates the Urban Climate Adaptation Theory and the Biophilic Design theory, articulating the mechanisms through which green infrastructure influences microclimate dynamics. Expected findings suggest that areas with dense green infrastructure exhibit significantly lower surface and air temperatures—potentially reducing UHI intensity by up to 3°C—compared to areas lacking such features. Specific types of green infrastructure, such as mature urban forests and extensive green roofs, are anticipated to demonstrate greater cooling effects. The spatial analysis is expected to reveal hotspots where UHI mitigation is most effective, influenced by factors such as vegetation maturity, canopy cover, and urban morphology. These findings will contribute to the empirical validation of green infrastructure as a practical UHI mitigation strategy, addressing existing gaps by providing quantifiable data on temperature differentials attributable to various GI forms in a dense urban environment. The study advances knowledge in urban climate resilience and sustainable planning by offering an evidence-based assessment of green infrastructure's effectiveness, facilitating informed decision-making for urban planners and policymakers. It concludes that strategic investments in green infrastructure can substantially mitigate UHI effects, provided that planning incorporates considerations of vegetation type, spatial distribution, and maintenance. Recommendations include prioritizing the development of mature urban forests and green roofs in heat-sensitive zones, integrating green infrastructure into urban planning policies, and fostering community involvement in green space management. The research also identifies areas for further investigation, such as longitudinal studies to evaluate the long-term impacts of GI and modeling to predict future UHI scenarios under climate change. Overall, this study underscores the critical role of green infrastructure as an adaptive and sustainable urban climate mitigation measure, emphasizing that targeted planning and implementation can significantly enhance urban thermal comfort and resilience.