Tidal-Driven Water-Salt Transport Dynamics in Coastal Subsurface Brine Mining Zones

This study mainly focuses on the laws governing the replenishment of coastal subsurface brine with marine-derived salts. Taking Yangkou Saltworks in Laizhou Bay as a case study, we integrated field monitoring with numerical modeling. Fieldwork included electrical resistivity tomography (ERT) and groundwater multi-parameter measurements across tidal cycles. The established hydrogeological model simulated water-salt migration under tidal influence. Results demonstrate a dual-peak salinity supply pattern. Larger tidal ranges advanced the first salinity peak by 1 h while reducing peak concentration by 0.2~0.3 g/L. Cessation of brine mining triggered seawater intrusion and salinity loss. Tidal creek networks were identified as critical pathways for the first salinity peak formation. Key findings reveal that tidal dynamics control the phreatic brine salinity variation amplitude. The high-permeability tidal creek system enables rapid salt transport. Subsurface brine mining activities dominate the land-sea hydraulic gradient. This study provides theoretical support for optimizing brine resource management in coastal zones.