Abstract
Traditional coastal flood hazard studies do not typically account for rainfall-runoff processes in quantifying flood hazard and related cascading risks. This study addresses the potential impacts of antecedent rainfall-runoff, tropical cyclone (TC)-driven rainfall, and TC-driven surge on total water levels and its influence in delineating a coastal flood transition zone for two distinct coastal basins in southeastern Louisiana (Barataria and Lake Maurepas watersheds). Rainfall-runoff from antecedent and TC-driven rainfall along with storm surge was simulated using a new rain-on-mesh module incorporated into the ADCIRC code. Antecedent rainfall conditions were obtained for 21 landfalling TC events spanning 1948–2008 via rain stations. A parametric, TC-driven, rainfall model was used for precipitation associated with the TC. Twelve synthetic storms of varying meteorological intensity (low, medium, and high) and total rainfall were utilized for each watershed and provided model forcing for coastal inundation simulations. First, it was found that antecedent rainfall (pre-TC landfall) is influential up to 3 days pre-landfall. Second, results show that antecedent and TC-driven rainfall increase simulated peak water levels within each basin, with antecedent rainfall dominating inundation across the basin's upper portions. Third, the delineated flood zones of coastal, transition, and hydrologic show stark differences between the two basins.
Highlights
The great Louisiana flood of 2016 resulted in immediate and lingering flooding impacts that exemplify a need to understand better the interplay between hydrologic, tide, and surge processes
Twelve synthetic storms of varying meteorological intensity and total rainfall were utilized for each watershed (Barataria and Lake Maurepas) and provided model forcing for simulations of coastal inundation
It was found that antecedent rainfall is influential up to 3 days pre-landfall
Summary
The great Louisiana flood of 2016 resulted in immediate and lingering flooding impacts that exemplify a need to understand better the interplay between hydrologic, tide, and surge processes. More than a week after the extreme rainfall event, the overland and riverine flows resulted in unsuspected complications. Areas in the lower portions of the watershed are vulnerable to hurricane storm surges, which warrants consideration of the contribution from both overland and coastal flows to flood hazards and flood risk (Leonard et al, 2014; Wahl et al, 2015; Wu et al, 2018). Similar events have occurred, resulting in complex interactions between rainfall- and coastal-induced flooding: Hurricane Rita followed Katrina
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
