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Abstract. We investigate here the effects of geometric properties (channel depth andcross-sectional convergence length), storm surge characteristics, friction,and river flow on the spatial and temporal variability of compound floodingalong an idealized, meso-tidal coastal-plain estuary. An analytical model isdeveloped that includes exponentially convergent geometry, tidal forcing,constant river flow, and a representation of storm surge as a combination oftwo sinusoidal waves. Nonlinear bed friction is treated using Chebyshevpolynomials and trigonometric functions, and a multi-segment approach isused to increase accuracy. Model results show that river discharge increasesthe damping of surge amplitudes in an estuary, while increasing channeldepth has the opposite effect. Sensitivity studies indicate that the impactof river flow on peak water level decreases as channel depth increases,while the influence of tide and surge increases in the landward portion ofan estuary. Moreover, model results show less surge damping in deeperconfigurations and even amplification in some cases, while increasedconvergence length scale increases damping of surge waves with periods of 12–72 h. For every modeled scenario, there is a point where river dischargeeffects on water level outweigh tide/surge effects. As a channel isdeepened, this cross-over point moves progressively upstream. Thus, channeldeepening may alter flood risk spatially along an estuary and reduce thelength of a river estuary, within which fluvial flooding is dominant.
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This content will become publicly available on December 1, 2026
Breaking down annual and tropical cyclone-induced nonlinear interactions in total water levels
With the increase of tropical cyclone activity, coastal communities will experience growing impacts from extreme water levels and associated compound flooding. Multiple drivers contribute to total water level (TWL), including mean sea level, astronomical tides, riverine flow, storm surges, and waves. Therefore, gaining insight into future TWL variability requires a thorough understanding of how those drivers nonlinearly interact at different spatiotemporal scales. In this study, we developed a coupled coastal and wave model at sufficient spatial resolution to analyze: (i) tide–driver interactions and their nonlinear components stemming from surge, river flow, and wind-waves, and (ii) their spatiotemporal evolution across the pre-landfall, landfall, and post-landfall stages of tropical cyclones in the Chesapeake Bay, USA. Results show that tide–surge and tide–wave interactions, along with their nonlinear components, exhibit substantial annual variability, with extreme hurricanes producing abrupt and spatially distinct responses driven by low pressure anomalies in slow-moving storms and wind setup in faster systems. In contrast, tide–river interactions remain negligible except in the upper bay tributaries. A weak or neutral tide–driver interaction does not necessarily indicate a negligible nonlinear response. Rather, nonlinear interactions (NIs) generally act out of phase with their associated drivers, functioning as compensatory mechanisms that amplify or suppress TWL. These nonlinearities are transient and of high-frequency nature near the coast, but evolve into slower, more persistent fluctuations in upstream regions. As climate change reshapes coastal dynamics, a robust understanding of NIs is essential for designing effective flood protection, enhancing risk assessments, and developing informed adaptation strategies for extreme water levels.
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- Award ID(s):
- 2141461
- PAR ID:
- 10646574
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Advances in water resources
- ISSN:
- 0309-1708
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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