Interface Zones: Assessing Porosity for an Integrated Urban Blue Spaces in Davao City’s Seafront

Abstract

The complexity of interface zones—determined by level of access to water and edge porosity—defines the extent of urban land-water integration. This study investigates the spatial and functional connection between urban land and water in public open spaces of Davao City, Philippines.  Specifically, it explored the features of urban blue spaces across designated-use (9 stations), formal-use (4 stations), and informal-use (14 stations) typologies in the downtown Davao City seafront. A descriptive-exploratory approach integrating the spatial analysis with qualitative fieldwork was utilized to map the water's edge profile and quantitatively assess porosity levels by developing an index using factors such as land-water connection (C), land-water edge section (E), urban blue space use (U), and urban blue space edge (BSE). Findings revealed high porosity scores throughout most urban blue space sections, driven by complex water edges, direct waterline connections, and permeable designs that facilitate land-water connectivity and human interactions. The analysis revealed critical insights into urban blue space dynamics across edge types, using edge porosity and water accessibility as primary measures of land-water relationships. Important physical features that contribute to high porosity were identified, emphasizing the role of unrestricted access to water. These features vary by spatial typology and involve trade-offs among water edge design, functionality, and regulatory control. While enhancing land-water connectivity, these attributes present management challenges inherent to waterfront public open spaces. The findings underscore the necessity of context-sensitive planning approaches that balance porosity, security, equity, and ecology to enhance recreational, aesthetic, and resilient waterfronts, aligning with studies on blue-green integration.