Objective The water-sealing safety of underground water-sealed caverns relies on a stable seepage field. In severe cold regions, extreme seasonal hydrological conditions—such as interrupted precipitation recharge due to surface freezing, the effects of low ground temperatures on groundwater rheology, and seasonal fluctuations in precipitation and river levels—directly impact cavern water-sealing safety. Understanding the mechanisms by which seasonal hydrological variations in severe cold regions influence the groundwater seepage field is crucial for accurately assessing water-sealing safety and ensuring the long-term stability of such projects.

Methods A refined three-dimensional fracture network hydrogeological model was established based on on-site investigation and monitoring data from an underground water-sealed cavern in northern China. Numerical simulations were conducted using this model to analyze the effects and mechanisms of seasonal precipitation, river level fluctuations, and climate temperature on the groundwater seepage field.

Results The model effectively simulated seepage field characteristics under complex hydrogeological conditions in severe cold regions. In the studied reservoir area, seasonal precipitation significantly influenced groundwater levels, causing variations of 3.4–7.9 m. Seasonal river level fluctuations had a limited impact on the seepage field, while climate temperature changes minimally affected groundwater temperature within the cavern’s elevation range. However, the average temperature difference between the north and south notably affected cavern seepage volume, with variations up to 46.6％.

Conclusion When the surface freezes in winter and precipitation recharge is interrupted, the water curtain system effectively stabilizes the groundwater level. The low temperatures of the northern underground constant-temperature layer increase groundwater viscosity, which, under the same water injection pressure in the water curtain holes, significantly reduces groundwater flow velocity and results in lower seepage volumes in caverns in severe cold regions. This study preliminarily demonstrates the regulatory effect of the water curtain system on the seepage field in terms of groundwater level, seepage volume, and streamline distribution. Future research could further investigate how design and operational parameters—such as spacing, aperture, and water injection pressure of water curtain holes—regulate groundwater level and seepage volume, providing a theoretical basis for the refined design and dynamic management of water curtain systems in underground water-sealed caverns.