Coastal inundation under concurrent mean and extreme sea-level rise in Coral Gables, Florida, USA

Southeast Florida (SF) is among the most vulnerable regions to sea-level rise in the United States of America. The consequences associated with sea-level rise (SLR) are already apparent, including coastal inundation and erosion. The Coral Gables Canal watershed is located in SF and can be considered representative of the effects of combined mean and extreme SLR. In this research, the effect of concurrent mean and extreme sea-level rise on coastal inundation in the Coral Gables Canal watershed is explored. A three-dimensional hydrodynamic model for Biscayne Bay and the Coral Gables Canal is presented. The model is used to estimate water surface elevations throughout the model domain, and map inundation due to an extreme water-level event (Irma Hurricane) occurring alongside mean SLR scenarios. A comparison of the inundation coverage calculated in this research to estimations made by several online tools shows that the online simulators underestimate flooding areas by 72% to 85%. This is a consequence of underpredicting maximum water surface elevations occurring under combined SLR in the Coral Gables Canal. The model predicts that under the NOAA Intermediate High SLR scenario (year 2100), 40% of the CGC watershed will be inundated (water depths > 0.6 m), and 70% of the area will be flooded with water depths greater than 1.6 m in year 2120. Under the NOAA High SLR scenario at least 70% of the Coral Gables Canal watershed would be inundated in 2100 (water depths > 1.0 m). In year 2120, 90% of inland sub-basins will be flooded (0.6 m < depths < 2.2 m). These results are significant for planning flooding/inundation risk management strategies.