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- Title
High‐Frequency Tide‐Surge‐River Interaction in Estuaries: Causes and Implications for Coastal Flooding.
- Authors
Spicer, Preston; Huguenard, Kimberly; Ross, Lauren; Rickard, Laura N.
- Abstract
Tide‐surge interaction creates perturbations to storm surge at tidal frequencies and can affect the timing and magnitude of surge in tidally energetic regions. To date, limited research has identified high‐frequency tide‐surge interaction (>4 cycles per day) in coastal areas, and its significance in fluvial estuaries (where we consider it tide‐surge‐river interaction) is not well documented. Water level and current velocity observations were used to analyze tide‐surge‐river interaction at multiple tidal and overtide frequencies inside of a shallow estuary. Near the head of the estuary, higher frequency harmonics dominate tide‐surge‐river interaction and produce amplitudes more than double that of wind and pressure‐driven surge. Bottom friction enhanced by storm‐induced currents is the primary mechanism behind the interaction, which is further amplified by within‐estuary resonance. High‐frequency tide‐surge‐river interactions in estuaries present a significant threat to human life, as the onset of flooding (in <1.5 hr) is more rapid than coastal storm surge flooding. Commonly used storm surge forecasting models neglect high‐frequency tide‐surge‐river interaction and thus can markedly underestimate the magnitude and timing of inland storm surge flooding. Plain Language Summary: Storm surges are a threat to life and property on the coast. How storm surges interact with tides varies by region and is not well understood, particularly in estuaries. This tide‐surge interaction, which we identify as tide‐surge‐river interaction in estuaries with a strong river influence, can affect the timing and magnitude of storm surges and so is important to understand. This study calculated storm surge and tide‐surge‐river interaction in a large estuary with strong tides after collecting water levels in the system for one Fall/Winter season. Results show that tide‐surge‐river interaction can more than double storm surges relative to the nontidal influenced surge and create rapid oscillations to water level that are hard to predict. Enhanced current velocities during storms from wind and surge propagation can cause tide‐surge‐river interaction, which can be further amplified by estuary geometry. Common surge models do not accurately resolve these high‐frequency tide‐surge‐river interactions. Key Points: Tide‐surge‐river interaction was shown to be largest in the sixth and eighth diurnal bandsHigh‐frequency tide‐surge‐river interaction can have amplitudes more than double that of low‐frequency surgeEnhanced bottom friction and resonance were the primary mechanisms causing tide‐surge‐river interaction at the D6 and D8 bands
- Subjects
TIDES &; the environment; FLOOD risk; ESTUARIES; FLOOD forecasting; STORM surges; OCEAN conditions (Weather)
- Publication
Journal of Geophysical Research. Oceans, 2019, Vol 124, Issue 12, p9517
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2019JC015466