Compound Coastal, Fluvial, and Pluvial Flooding During Historical Hurricane Events in the Sabine–Neches Estuary, Texas

Abstract

AbstractWhen storm surge, river discharge, and rainfall occur simultaneously or in succession, they may cause compound flooding and exacerbate impacts in coastal communities. In traditional modeling approaches, these driving processes are simulated separately, leading to discrepancies between simulated and observed data and highlighting the need for coupled modeling frameworks. Here, we develop a coupled coastal–fluvial–pluvial model for the Sabine–Neches Estuary in southeastern Texas using Delft3D to simulate flood extent and depth during Hurricanes Rita, Ike, and Harvey. For each hurricane, four scenarios (i.e., coastal, fluvial, pluvial, and compound) are modeled to determine the relative contribution of each driving force to water levels across the domain. Our results reveal that tropical cyclones such as Harvey that are accompanied by extended periods of rainfall produce the largest extent and longest duration of compound flooding. Such storms also produce highly dynamic and evolving patterns of compound flooding over their duration, with multiple flood peaks that can inhibit response and recovery efforts. When simulating these storms, a coupled model can provide substantial improvements over coastal‐, fluvial‐, and pluvial‐only models, decreasing root mean square error by 69%, 69%, and 79%, respectively. In contrast, storms with short‐duration rainfall and moderate to severe storm surge produce less extensive compound flooding, which is typically dominated by coastal–pluvial interactions. Our results further highlight the potential for compound flooding at the locations of critical water infrastructure assets, suggesting the need for flood adaptation approaches that are robust to multiple types of flooding.