Coastal regions face increasingly complex flood risks driven by the interplay of storm surge, river discharge, and extreme rainfall. Recent research highlights how tropical cyclones often trigger compound flooding events, where storm surge and heavy precipitation coincide, amplifying damage. These joint events are projected to become significantly more frequent because of climate change. Despite growing awareness, developing actionable design data remains challenging owing to limited historical records and the variability in how rainfall and surge interact across different storm types and regions.
To address these challenges, researchers Renato Amorim, Gabriele Villarini, Hanbeen Kim, Robert A. Jane, and Thomas Wahl offer a more comprehensive, flexible solution that can provide more accurate flood risk assessment. Building on previous studies, they introduce a detailed guide for engineers to generate rainfall and water level time series that account for compound flooding scenarios. This research, outlined in “A Practitioner’s Approach to Process-Driven Modeling of Compound Rainfall and Storm Surge Extremes for Coastal Texas,” applies their methodology to five watershed basins in coastal Texas and equips civil engineers with more reliable tools for designing resilient infrastructure in flood-prone coastal areas. Learn more about how this study can improve infrastructure design while mitigating risk in flood-prone coastal communities in the Journal of Hydrologic Engineering at https://ascelibrary.org/doi/10.1061/JHYEFF.HEENG-6482. The abstract is below.
Abstract
Coastal Texas is no stranger to riverine and coastal flooding and, while these events can be catastrophic on their own, they can have an even larger impact when they occur together, as in the case of compound extremes. While the emphasis has been on quantifying the compounding of these two hazards, much less is known about generating design rainfall events with a high space-time resolution and preserving the dependence with storm surge. This is particularly problematic in areas where there are limited records and multiple flood generating mechanisms. Here we focus on five watersheds in coastal Texas and develop an approach to generate design events for different annual exceedance probabilities (AEPs) subject to different compounding characteristics. We show that tropical cyclones (TCs) exhibit a stronger dependence between the nontidal residuals and precipitation than non-TC events, and we provide approaches to generate design events for both types of storms. Moreover, we propose to infill missing data in water levels to mitigate issues related to small samples. We also quantify the lag between rainfall and storm surge peaks. Our study provides a roadmap for practitioners who need to develop design events with high spatio-temporal resolution for different AEPs, and are dealing with compounding, mixed distributions, short record length, and lag between peak rainfall and storm surge.
Read the paper in full and see how it can enhance your flooding forecasts in the ASCE Library: https://ascelibrary.org/doi/10.1061/JHYEFF.HEENG-6482.
