AQUIFER PARAMETER ESTIMATION USING TIDE-INDUCED WATER TABLE FLUCTUATION IN MIAMI-DADE COUNTY, FLORIDA

Biscayne aquifer is a coastal, shallow, unconfined, and heterogeneous aquifer with high water tables composed of less permeable sand to highly permeable karstic limestone. These properties make the Biscayne aquifer one of the most prolific aquifers in the world but at the same time, one of the most vulnerable to contamination and flooding. Moreover, its high productivity causes complexity for the estimation of aquifer parameters, which are essential for understanding groundwater processes and managing and protecting groundwater resources.

Groundwater table fluctuations of the Biscayne aquifer are associated with lunar and solar tidal forces and gate operations on canal water-control structures. Observed groundwater table fluctuations can provide an understanding of the connectivity between the aquifer and the Bay and between the aquifer and the water level in the canals. Further, it can be used for aquifer parameter estimation.

In this research, we fit observed tide and groundwater levels to Jacob’s analytical solution, where the amplitude of the groundwater head fluctuation decreases exponentially, and the time lag increases with distance from the shore. We obtained observed groundwater levels from monitoring wells along the Miami-Dade shore and from monitoring wells on the barrier island of Miami Beach.

This study shows that groundwater levels in Miami Beach are highly correlated with tidal fluctuations, but groundwater levels from Miami-Dade coastal wells (except one) are not significantly correlated with tides, due to the great distance of monitoring wells from the shore and by management of water levels in the canals. We have found that Jacob’s solution is effective for aquifer parameter estimation in Miami Beach, where monitoring wells are closer to the shore. Constructing monitoring wells closer to the shore in Miami-Dade and elsewhere would be greatly beneficial for further analysis of groundwater table positions and aquifer parameter estimation.