Investigating compound flooding in a low elevation coastal karst environment using multivariate statistical and 2D hydrodynamic modeling

Abstract

Miami-Dade County is vulnerable to flash, pluvial, fluvial, coastal and groundwater flooding due to its low-elevation karst morphology. Despite considerable advances in understanding the impact of compound flooding events by considering major flood drivers (precipitation, river discharge, and coastal surge), little is known regarding the severity of groundwater hazards in this region. This study links a multivariate statistical analysis with a coupled physically-based 2D hydraulic model to estimate the flood hazard in the Arch Creek Basin located in North Miami. A bivariate copula analysis was used to capture the joint probability of key flood drivers with predefined water table thresholds to set-up the flood modeling conditions. Results demonstrate the high vulnerability to extreme precipitation events compared to coastal surge in the study area. Similarly, groundwater flooding is relevant in shallow water table environments, as it influences the severity of flood hazards in terms of flood inundation depth, extent, and damage to the built environment. This research demonstrates that groundwater flooding is a latent risk that should be incorporated in flood hazard mapping in regions susceptible to high water tables and sea level rise.