Probabilistic Flood Risks due to Combined Flooding in Southeast Harris County

This study discusses the development and performance of a rapid prediction system capable of representing the joint rainfall-runoff and storm surge flood response, or combined flood levels, of tropical cyclones (TCs) for probabilistic forecasting and frequency analysis. Due to the computational demand required for accurately representing storm surge with the high-fidelity hydrodynamic model ADvanced CIRCulation (ADCIRC) and its coupling with additional numerical models to represent rainfall-runoff, a surrogate or statistical model was trained to represent the relationship between hurricane wind- and pressure-field characteristics and their peak combined flood response typically determined from physics based numerical models. This builds upon past studies that have only evaluated surrogate models for predicting peak surge, and provides the first system capable of probabilistically representing combined flood levels from TCs. The utility of this combined flood prediction system is then demonstrated by improving upon probabilistic TC flood forecasting and frequency products, which currently account for storm surge but do not take into account TC associated rainfall-runoff.