Assessing the Impact of Green Infrastructure on Urban Heat Island Mitigation

Thesis Abstract

Urban areas worldwide are experiencing escalating temperatures due to the intensification of the urban heat island (UHI) effect, which exacerbates energy consumption, air pollution, and health risks among urban populations. Despite increasing implementation of green infrastructure (GI) interventions such as green roofs, urban parks, and vegetated corridors, empirical assessments of their effectiveness in mitigating UHI phenomena remain limited and context-specific. This study aims to evaluate the impact of green infrastructure on UHI reduction through a comprehensive empirical analysis within the metropolitan area of a rapidly urbanizing city. The specific objectives are to quantify the thermal modulation effects of different GI typologies, identify spatial variability in UHI mitigation, and establish the relationship between green infrastructure distribution and surface temperature variations. Employing a mixed-methods research design, the study integrates quantitative spatial analysis with qualitative stakeholder insights. The population of the study comprises urban residents, city planners, and environmental agencies involved in green infrastructure projects across the city’s administrative zones. A stratified random sampling approach is used to select 350 households for temperature exposure surveys, and 20 key informants from municipal agencies are purposively sampled for semi-structured interviews. Geographic Information System (GIS) tools are used to map green infrastructure distribution and to extract remotely sensed thermal data obtained from Landsat 8 satellite imagery, capturing surface temperatures during peak summer months over two consecutive years. Quantitative data from satellite imagery and in-situ temperature sensors are subjected to descriptive statistics, correlation analysis, and multiple regression modeling to evaluate the relationship between green infrastructure variables and surface temperature reductions. Specifically, a stepwise multiple regression analysis is employed to identify which types of GI contribute most significantly to UHI mitigation, accounting for variables such as vegetation cover density, size, and spatial configuration. Spatial autocorrelation techniques, including Moran’s I, are used to assess the spatial clustering of temperature anomalies, while a difference-in-differences approach compares thermal profiles before and after GI interventions. Qualitative data from interviews are thematically analyzed using NVivo to contextualize quantitative findings within stakeholder perceptions and policy frameworks. The study anticipates revealing that green infrastructure significantly reduces surface temperatures, with vegetated corridors and large urban parks demonstrating the highest mitigation potential. Findings are expected to show a statistically significant negative correlation between green cover density and surface temperature, confirming the thermal buffering capacity of vegetated spaces. The spatial analysis is projected to identify hotspots where GI implementation is limited or ineffective, thus guiding targeted interventions. The research contributes new empirical evidence on the specific types and configurations of green infrastructure that most effectively mitigate urban heat, advancing the theoretical understanding of green urbanism within the framework of the Biophilia Theory and Sustainable Urban Design. This research provides actionable insights for urban planners and policymakers to optimize green infrastructure deployment for climate resilience and urban sustainability. It emphasizes the importance of integrating spatially explicit data analysis with stakeholder engagement to ensure that GI strategies are contextually appropriate and socially acceptable. The study concludes that strategic placement and selection of green infrastructure can substantially mitigate the UHI effect, thereby enhancing urban environmental quality and livability. Recommendations include prioritizing large-scale vegetated corridors, fostering community involvement in green space maintenance, and adopting integrated urban climate mitigation policies. Future research avenues suggested include exploring the long-term impacts of green infrastructure adoption and evaluating the socioeconomic benefits associated with UHI reduction strategies.