Engineering geological factors controlling the long-term performance of ancient masonry water structures: Insights from the Urartian Water Supply System

Ancient masonry water structures provide valuable case studies for evaluating long-term structural performance. The Urartian Water Supply System (UWSS), constructed approximately 2800 years ago around Lake Van in Eastern Anatolia, comprises canals, dams, and river barriers that remain partially functional despite prolonged tectonic activity and erosion. These structures offer an opportunity to examine how engineering geological conditions, foundation characteristics, and construction materials influence long-term structural behaviour. This study presents an integrated engineering geological assessment of selected UWSS elements. Field investigations focused on foundation lithology, geomorphological setting, and site conditions, while laboratory analyses determined the physical and mechanical properties of construction materials. Finite Element Method (FEM) analyses were conducted to evaluate stress distribution and deformation under hydrostatic and seismic loading. Results show that hydrostatic loading alone produces limited structural response with a maximum deformation of approximately 0.035 mm, whereas seismic loading (0.3–0.4 g) increases maximum equivalent stress to 0.52–0.56 MPa and total deformation to 0.137–0.148 mm. The highest stresses are concentrated in the lower and central zones of the barrier, showing substantial spatial correspondence with the observed damage. Although masonry blocks exhibit adequate compressive strength, structural performance is controlled by weaker binder materials, heterogeneous foundation conditions, and environmental processes such as erosion. The consistency between modelled stress patterns and observed damage supports a multi-process interpretation of deterioration. These findings highlight the importance of integrating engineering geological observations with numerical modelling for assessing and conserving historical masonry structures in tectonically active regions.