A Framework for Modelling Tropical Cyclone-Induced Compound Flooding of the Continental US: Demonstrated in New Orleans

Compound flooding involves the interaction of multiple flood processes (e.g., coastal, fluvial, and pluvial) and is modulated by several factors (e.g., weather, climate, topography, morphology, time-lag). In many of the world’s tropical and subtropical regions, Tropical Cyclones (TCs) are a primary cause of compound flooding as they generate substantial rainfall runoff and subsequent elevated river discharge, in combination with strong winds and low-pressure systems that produce large storm surges and waves. In this study, we develop a novel 30m resolution compound flood modeling framework centered around Lisflood-FP, SCHISM-WWIII, SFINCS, FUSE, and MizuRoute to simulate compound coastal-fluvial-pluvial flooding across the continental US. This framework is demonstrated by simulating compound flooding associated with 9 historical TC events in the Greater New Orleans Metropolitan Area and the surrounding Mississippi River Delta. Findings reveal several regions that regularly encounter compound flood interactions during TC events, with the most prominent being Lake Maurepas, Lake Pontchartrain, and surrounding coastal estuary basins. For all TC events, the average flood disturbance across sites of nonlinear compound interactions is found to be underestimated by 60% or more if flood drivers are simulated separately and summed. Preliminary relationships are identified between TC characteristics and the extent and magnitude of compound flood interactions, suggesting that greater compounding correlates with intense (low center pressure, high rainfall rate, and high max wind velocity) but concentrated (small maximum wind radius) storm events. Lastly, skilled performance is observed by the model framework given the complex study area, which can be replicated for future research.