Abstract: [Objective]In strongly deformed tectonic regions, the structure of multi - layer water - bearing systems varies intensively in space. This leads to intricate patterns of groundwater occurrence and migration, presenting formidable challenges for predicting the risk of water inrush in deep - buried water diversion tunnels and for related engineering construction. During the construction of the water conveyance tunnel of the Middle Route of the South - to - North Water Diversion Project's Yangtze River to Han River Supplement Project, which traverses the Cambrian - Ordovician multi - layer karst water - bearing system of the Jindou-Anzizhai compound anticline, numerous exploration boreholes have uncovered high - pressure and high - discharge confined water. As a result, the risk of high - pressure water inrush during tunnel construction is extremely high. [Method]This study comprehensively utilized multiple methods and techniques, including hydrogeological drilling, down - hole video recording, hydrochemical analysis, isotopic analysis, and hydro - dynamic monitoring. These were employed to unveil the recharge, occurrence, and migration mechanisms of confined water within the multi - layer water - bearing system and to identify the tectonic features that govern groundwater enrichment. [Result]The research findings indicate that the Jindou-Anzizhai karst water - bearing system features a multi - layer structure in the vertical direction, with alternating karst water-bearing strata and aquitards. Due to the obstruction of aquitards, the development of buried karst is relatively subdued, and the water-bearing medium is predominantly composed of fractures. The confined water is primarily of the HCO3-Ca·Mg water water. Its TDS is slightly higher than that of surface karst springs, and notable isotopic fractionation occurs. This suggests that the confined water has a long flow path, slow circulation and replacement rates, and cannot directly receive modern rainfall recharge. The water - bearing strata only outcrop at the surface in mountainous areas to receive recharge. Under the combined influence of topography, tectonics, and aquitards, the groundwater generally flows from the west and south towards the east and north, and is discharged into the Qingxi River via the Tumeng Fault. [Conclusion]The high recharge source, long flow path, and narrow discharge channel of groundwater are the fundamental causes for the formation of high - head confined water. Fault fracture zones, the cores of folds, and the interfaces between water - bearing strata and aquitards are the concentrated flow zones where confined water accumulates. When the tunnel traverses these areas, there exists a high risk of high - pressure water inrush. The source of water inrush is mainly the elastic storage volume of confined water, characterized by a large initial water inrush volume, and a gradual attenuation of water inrush volume and water pressure over time. The research results can offer valuable references for identifying the hydrogeological conditions of deep - buried tunnels in similar tectonically active regions.