Abstract:

Groundwater levels in a coastal leaky confined aquifer may fluctuate as a result of the induction of the tide.A numerical model describing 1D groundwater flow in a coastal leaky confined aquifer is established in this paper based on the finite element method.By simplifying the fluctuation in the tide as a sinusoidal wave, groundwater level oscillations in a coastal leaky confined aquifer with horizontal and linear slope initial groundwater levels are modeled.Comparison of the modeling results of these two cases shows that the groundwater level oscillations induced by the tide in the coastal confined aquifer are similar to those of the tide but the fluctuation ranges of groundwater levels are smaller than those of the tide.The degree of effect by the tide is related to distance from the coast.The fluctuation range of groundwater levels and the tidal efficiency decrease negatively exponentially with the distance from the coast.The fluctuation range, tidal efficiency and time lag of groundwater levels in the confined aquifer with horizontal initial groundwater level are smaller than those of the aquifer with linear slope initial groundwater level.The time lag of the groundwater levels to the tide increases linearly with the distance from the coast.

Key words: leaky confined aquifer, tidal effect, numerical model, coastal aquifer, groundwater