Bigger tides, less flooding: Effects of dredging on barotropic dynamics in a highly modified estuary.

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2018-12-11Author
Ralston, David K.
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Talke, Stefan
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Geyer, W. Rockwell
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Al‐Zubaidi, Hussein A. M.
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Sommerfield, Christopher K.
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https://hdl.handle.net/1912/23752As published
https://doi.org/10.1029/2018JC014313DOI
10.1029/2018JC014313Keyword
barotropic tides; flood frequency; storm surge; dredging; estuary; tidal riverAbstract
Since the late nineteenth century, channel depths have more than doubled in parts of New York Harbor and the tidal Hudson River, wetlands have been reclaimed and navigational channels widened, and river flow has been regulated. To quantify the effects of these modifications, observations and numerical simulations using historical and modern bathymetry are used to analyze changes in the barotropic dynamics. Model results and water level records for Albany (1868 to present) and New York Harbor (1844 to present) recovered from archives show that the tidal amplitude has more than doubled near the head of tides, whereas increases in the lower estuary have been slight (<10%). Channel deepening has reduced the effective drag in the upper tidal river, shifting the system from hyposynchronous (tide decaying landward) to hypersynchronous (tide amplifying). Similarly, modeling shows that coastal storm effects propagate farther landward, with a 20% increase in amplitude for a major event. In contrast, the decrease in friction with channel deepening has lowered the tidally averaged water level during discharge events, more than compensating for increased surge amplitude. Combined with river regulation that reduced peak discharges, the overall risk of extreme water levels in the upper tidal river decreased after channel construction, reducing the water level for the 10‐year recurrence interval event by almost 3 m. Mean water level decreased sharply with channel modifications around 1930, and subsequent decadal variability has depended both on river discharge and sea level rise. Channel construction has only slightly altered tidal and storm surge amplitudes in the lower estuary.
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Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124 (2019): 196-211, doi:10.1029/2018JC014313.
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Ralston, D. K., Talke, S., Geyer, W. R., Al-Zubaidi, H. A. M., & Sommerfield, C. K. (2019). Bigger tides, less flooding: Effects of dredging on barotropic dynamics in a highly modified estuary. Journal of Geophysical Research: Oceans, 124, 196-211Related items
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