Urban Heat Exposure and Access to Cooling: A Network-based Analysis for Urban Green Space Accessibility in the Colombo Metro Region Area. Jayathilaka H. B.T.P1*, Ranasinghe D.A.S.M.2, Shiyan Zhai3, and Somasekara J.P.S.4
1College of Geographical Sciences: Reading PhD, Henan University, China
2Geography Information System Division: Assistan Director (Town Planning), Urban Development Authority, Sri Lanka
3College of Geographical Sciences: Professor, Henan University, China
4 Geography Information System Division: Director, Urban Development Authority, Sri Lanka
Abstract
Rapid urbanization, coupled with infrastructure development, reduction and fragmentation of green spaces, increases urban heat islands. Urban heat (UH) poses a threat to public health, and urban green spaces (UGS) benefit the well-being of residents while supporting sustainable urbanization and climate regulation services. Studying accessibility is a complex and dynamic process, and a gap remains in urban planning and accessibility studies regarding UGS, especially in developing countries. By addressing these gaps, this study focused on assessing UH distribution and UGS accessibility and identifying functionally beneficial areas in the Colombo Metro Region, which is the urban core of Sri Lanka. This study utilized secondary data, including Landsat images, land use, road networks, green infrastructure, and building data, and integrated them with remote sensing and GIS-based accessibility analysis. To determine which cooling areas are truly accessible to residents, appropriate accessibility metrics are applied. A service area analysis is then conducted, using buffer zones of 500 m, 1000 m, and 1500 m, to identify the areas served by the accessible cooling locations. The results reveal that main UGSs such as Angoda, Malabe Thangama, and Thalangama provide cooling services to Battamulla and Kaduwela, while heat-stressed zones, including Grandpass, Dehiwala-Mount Lavinia, Ratmalana, Maharagama, and Borella, remain underserved. There are 15% of residential buildings in high UH zones that fall within 500 m of accessible UGS, highlighting that 85% of heat-affected residents lack easy access to cooling spaces. It shows a critical cooling service gap in climate resilience infrastructure and an urgent need for heat vulnerability and equitable UGS access in urban planning. Developing green parks, introducing UH resilience zones, and supporting community-led cooling initiatives are highly recommended for this area, while providing actionable insights for urban planners and policymakers to encourage equitable access to UGS and improve climate resilience in urban environments.
Keywords: Urban green spaces, urban heat, network analysis, accessibility
