Tidal fluctuations in coastal aquifers offer critical insights into the controls and dynamics of groundwater flow systems. This study presents a new analytical model designed to examine tide-driven variations in groundwater levels, particularly in systems with complex boundary conditions. Unlike previous models, the proposed model incorporates the effects of semi-permeable zones at interfaces and partial boundary penetration near estuaries. Sensitivity analyses were used to evaluate how intricate boundary configurations and specific aquifer characteristics influence the amplitude and phase shift of tidal signals in aquifers. The new analytical approach was also applied to data from a coastal aquifer in Hong Kong, and the results emphasized the importance of accounting for partial estuary penetration when evaluating tidal signal propagation. This approach significantly advances understanding of tidal signal propagation in coastal aquifers, offering a more comprehensive assessment of aquifer behavior that extends beyond hydraulic diffusivity.
