Planning for Spatial Equity in Heritage Cities: A GIS Assessment of Public Green Infrastructure and Service Accessibility

In historical urban environments, heritage conservation frequently generates spatial tensions between protected core zones and expanding peripheral residential areas, resulting in asymmetric public space allocation and fragmented mobility networks. While metropolitan land-use sustainability is widely examined, medium-sized heritage cities remain underrepresented, despite facing distinct trade-offs between historic preservation, everyday liveability, and intra-urban cohesion. To bridge this research gap, this study proposes a comprehensive GIS-based framework utilizing urban sustainability indicators to evaluate spatial equity, public service accessibility, and territorial cohesion in the historic city of Mérida, Spain. Based on the Spanish Urban Agenda criteria, eight indicators were operationalized and categorized into three thematic dimensions: (1) green spaces and biodiversity, (2) urban metabolism, and (3) social cohesion. Employing spatial topology, microdata, and network analysis across official municipal datasets, structural connectivity and service distribution were evaluated between contrasting spatial sectors (the historic centre versus the broader urban core). The findings reveal a heterogeneous spatial pattern of environmental and social performance. While the historic centre exhibits favourable green space provision and ecological corridor connectivity, it suffers from reduced population proximity to these assets, highlighting an underlying spatial equity gap. Conversely, the expanding urban core benefits from spatial growth but demonstrates critical deficiencies in public facility accessibility, further exacerbated by aging demographic trends. The study concludes that urban sustainability in heritage cities cannot rely solely on physical resource provisioning; it demands integrated spatial planning and targeted accessibility policies. These insights provide empirical and actionable knowledge to update Sustainable Urban Mobility Plans (SUMPs) and land-use strategies in UNESCO World Heritage cities.