Chatham County Health & Air Quality: Mapping Urban Heat to Identify Priority Mitigation Areas in Chatham County, Georgia

Recent development within Chatham County, Georgia have replaced natural tree canopy, raising concerns about increased urban heat island (UHI) impacts. To combat urban heat, the Chatham County Government has sponsored tree canopy evaluations and set up cooling stations during peak summer months. In an effort to help the local government better characterize county-wide UHI impacts, we used optical and infrared imagery from the NASA/USGS Landsat 8 Operational Land Imager (OLI) and, Thermal Infrared Sensor (TIRS), Landsat 9 OLI-2 and TIRS-2, ISS ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station, and National Land Cover Database imagery to map changes in urban heat and vegetation during growing season months between 2014 and 2024. Additionally, we combined the U.S. Census Bureau’s community resilience index for heat with environmental risk factors to develop a heat vulnerability index between 2020 and 2022. We also used the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Urban Cooling Model from the Natural Capital Project to create a heat mitigation index for 2021. We found that changes in urban heat and vegetation were both concentrated towards the northwestern part of the county and associated with development activities. We additionally found that the county lost nearly 17% of its existing canopy between 2014 and 2024. Lastly, our analyses of both heat vulnerability and heat mitigation indicate that urbanized areas have high susceptibility to heat stress. The results suggest that Earth observations can be used to map heat-related environmental factors that contribute to the UHI effect in Chatham County and support new policy initiatives and community outreach efforts around urban heat in the county.