The enhancing effect of the elastic storage of the seabed aquitard on the tide-induced groundwater head fluctuation in confined submarine aquifer systems

SummaryThis paper investigated the tide-induced head fluctuation in a coastal confined aquifer with an infinitely-extending semipermeable roof. The roof is overlain by an unconfined aquifer terminating at the coastline. Previous analytical studies ignored the effect of the elastic storage of the semipermeable roof. Our model incorporated this effect. The analytical solution indicated that the increase of the elastic storage of the offshore semipermeable roof may significantly enhance the tidal head fluctuation in the confined aquifer at the coastline. A threshold leakance exists in the sense that when the leakance is less than the threshold, the head fluctuation at the coastline will become insensitive to leakance and the roof can be regarded as impermeable. The threshold strongly depends on the roof’s elastic storage and decreases as the roof’s elastic storage increases, indicating that the roof’s leakage effect is significantly enhanced by the increase of the roof’s elastic storage.