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Abstract Compound floods are often thought of as large, infrequent floods during which extremes of coastal sea level and/or river flow combine with each other or additional factors (e.g., tides and rainfall) to induce major flooding. However, little is known about the potentially compound nature of more frequent, lower‐level floods. Here, we introduce the term “compound minor floods” to define minor floods composed of two or more water‐level sources. We use the Delaware River Estuary as a case study to investigate the prevalence and composition of these minor compound floods along the extent of a tidal river. We apply multiple linear regression to a 22‐year time series of coastal water levels and river discharge to establish the contributions of tides, nontidal open‐ocean effects, and river discharge to minor flood events at eight locations along the tidal Delaware River. We find that most minor flood events are compound in nature, requiring at least two components (e.g., tides and river discharge) to initiate flooding. We identify spatial structure in the relative importance of oceanographic and riverine contributions to minor flooding along the tidal reach of the estuary. These results suggest that incorporating fluvial components into minor flooding assessments is important to fully characterize flood risk along tidal rivers and estuaries.
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This content will become publicly available on May 16, 2026
Analyzing Compound Flooding Drivers Across the US Gulf Coast States
Abstract Analyzing flood events has been the focus of numerous studies across local, regional, and global scales, aiming to understand their magnitude, drivers, and spatiotemporal distributions. Traditionally, flood hazards are defined by analyzing the likelihood of flood drivers exceeding their respective thresholds. This approach relies on events around gauge locations with accessible records. The availability of reanalysis and satellite data sets now allows us to leverage data from multiple flood reporting agencies to examine various flood event types, including compound and non‐compound events, and their drivers. We analyzed three decades of flood events in the US Gulf Coast states, where compound flood events are common. We found that rainfall is the predominant driver, contributing to over 45% of reported floods classified as compound events. Fluvial and pluvial floods are more frequent and severe during tropical seasons, and especially during the Fall compared with other calendar seasons.
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- Award ID(s):
- 2223893
- PAR ID:
- 10640507
- Publisher / Repository:
- AGU
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 52
- Issue:
- 9
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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