Historic Water Infrastructure as an Urban-Spatial System in the Old City of Mardin: A Multi-Scalar Spatial-Decoding Approach

Historic water infrastructure has often been treated primarily as a technical system, while its relationships with urban form, architectural organization, and everyday life have received less attention. Focusing on the old city of Mardin, this study examines historic water infrastructure, including partially accessible underground routes and their above-ground interfaces, as a constitutive component of spatial organization in a settlement shaped by arid climatic conditions and steep topography. A multi-scalar spatial-decoding approach combines Quantum Geographic Information System (QGIS)-based mapping, morphological and sectional analysis, Light Detection and Ranging (LiDAR)-based three-dimensional documentation, archival research, field observation, and oral testimony. The findings reveal a decentralized configuration of largely independent gravity-fed source-to-outlet routes embedded across urban and architectural scales. Water access, maintenance requirements, and architectural integration contributed to the organization of public nodes, institutional buildings, domestic spaces, and everyday practices without independently determining them. The transition to centralized modern supply disrupted these embedded relationships and transformed the visibility, accessibility, use, and situated knowledge of water. Methodologically, the study offers a transferable cross-scalar approach for reconstructing relationships between partially concealed infrastructure and visible urban form.