PROJECTED MIAMI-DADE COUNTY FLORIDA GROUNDWATER TABLE ELEVATIONS TO THE YEAR 2070 WITH AN UPDATED BASE RUN OF THE URBAN MIAMI-DADE GROUNDWATER MODEL

Miami-Dade County is a low-lying, highly populated coastal area. South Florida, including Miami-Dade County, is underlain by the shallow karst unconfined Biscayne Aquifer, and is vulnerable to flooding and saltwater intrusion. The aquifer's water levels interact with surface water, including the ocean, bay, Everglades, and stage-managed canals. On the east side, groundwater levels are affected by the sea level changes, and on the west side, by changes in water levels in the Everglades. All climate-related factors affecting groundwater are continuously changing; however, sea level rise and water levels in Everglades changed drastically in the last decade. The most recent groundwater model developed by the USGS for Miami-Dade County has a base run from 1996 to 2010. Since 2010 the sea level has risen following the quadratic trend of the NOAA intermediate high sea level scenario, and there has been a water level increase in the Everglades due to Everglades restoration initiatives. In addition, to reduce groundwater flow from Everglades National Park to the L31-N canal, a two-mile seepage barrier was built in 2012 and extended by three miles in 2016. The next phase, including an additional two miles of seepage wall, is under construction and expected to be finished by the end of 2022. In this study, we extended the base run to 2020 with historical conditions and used the model to project water table elevations to 2070, assuming the NOAA intermediate high sea level rise curve. We added the Horizontal Flow Barrier package to simulate the impacts of the seepage barrier on flows and heads for both historical and future scenarios.