Subsurface tidal analysis requires only continuous pressure monitoring
data and therefore can be a cost-effective technique for estimating
aquifer properties. The tidal behavior of a well in a semiconfined
aquifer can be described by a diffusion equation that includes a leakage
term. This approach is valid for thin aquifers, as long as the overlying
layer has low permeability relative to the main aquifer. However, in
cases where the aquifer is not thin and the permeability of the
overlying layer is not low, using the existing solutions based on these
approximations may lead to unsatisfactory outcomes. Alternative
solutions for both vertical and horizontal wells were obtained by
solving the standard diffusion equation, with leakage expressed as a
boundary condition. Furthermore, a nondimensional number was derived
mathematically, which forms the basis for a quantitative criterion to
assess the applicability of the existing solutions. In the case of a
vertical well, the existing solution exhibits acceptable error only if
the nondimensional number is less than 0.245. Our new solution extends
this upper limitation to 0.475. However, when the number is greater than
0.475, both the existing solution and our new solution are invalid due
to the invalid uniform flowrate assumption. For a horizontal well, when
the number is less than 0.245, the existing solution is suitable with
acceptable error. Our new solution effectively overcomes this
limitation. Finally, the new solution was applied to the case of the
Arbuckle aquifer to demonstrate the improved validity of the new
solution compared to the existing one.