This study investigates saltwater intrusion (SWI) dynamics in the Biscayne aquifer, which includes two scenarios (1) simulation scenarios were developed using SEAWAT to assess the aquifer’s response to sea level rise (SLR) and tidal fluctuation-induced pressure waves at the base case (before using seawall) and (2) using seawall intervention to mitigate SWI and SLR flooding. SLR projections were modeled using boundary conditions informed by National Oceanic and Atmospheric Administration (NOAA) and The Intergovernmental Panel on Climate Change (IPCC) data, revealing progressive SWI advancement up to 8900 m intrusion under +2.62 m SLR compared to the baseline where the SWI extent was 7950 m. Tidal impacts, modeled using observed Broward County tidal ranges and an amplified sinusoidal (SIN) wave, showed intrusion length up to 8750 m for the tidal fluctuations value of +2.31 m. Seawall height requirements to manage overtopping were calculated using empirical wave run-up models, indicating a minimum design height of 7.5 m to resist a worst-case SLR of +2.62 m and maximum tide of +2.31 m. The findings underscore the importance of adaptive coastal management, integrating engineering solutions with hydrogeologic and ecological considerations.