Abstract
Underground hydraulic structures (hydraulic tunnels, drainage collectors, galleries within hydraulic units, water conveyance chambers, underground water reservoirs, etc.) are long-service-life engineering facilities belonging to a high-risk category. Over time, the technical condition of these structures may deteriorate due to hydrostatic pressure, seepage flows, aggressive environmental conditions, soil deformation, seismic effects, and operational loads. This paper presents the scientific foundations of monitoring systems used to assess the technical condition of underground hydraulic structures and to ensure safe operation, including sensor and measurement technologies, digital data architecture, diagnostic indicators, and risk-based decision-making models. In addition, the advantages of integrating traditional geodetic observations with modern IoT/SCADA solutions, fiber-optic monitoring technologies (DAS/DTS/FBG), non-destructive testing (NDT) methods, the “digital twin” concept, and predictive maintenance approaches are analyzed. As a result, a comprehensive monitoring model is proposed, and practical recommendations are provided for continuous control of structural serviceability, seepage stability, and overall structural integrity.