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Strong inland propagation of low‐frequency long waves in river estuaries

Strong inland propagation of low‐frequency long waves in river estuaries
Strong inland propagation of low‐frequency long waves in river estuaries
Tidal waves traveling into estuaries are modified by channel geometry and river flow. The damping effect of river flow on incident astronomical tides is well documented, whereas its impact on low‐frequency tides like MSf and Mm is poorly understood. In this contribution, we employ a numerical model to explore low‐frequency tidal behavior under varying river flow. MSf and Mm are locally generated by frictional mechanisms inside an estuary, and they are larger in amplitude far upstream in tidal rivers and persist landward of the point of tidal extinction. Increasing river flow nonlinearly modulates the longitudinal variations of MSf and Mm amplitudes. This is dynamically explained by flow‐enhanced asymmetry in subtidal friction over the spring‐neap (MSf) and perigee‐apogee (Mm) cycles, respectively. Estuaries act as frequency filters, where low‐frequency waves decay at a smaller rate and propagate more inland than high‐frequency waves. Strong inland penetration of low‐frequency tides informs compound flood management.
MSf, low-frequency, river discharge, subtidal friction
0094-8276
Guo, Leicheng
17e93f75-1537-481e-bba6-c9217b42428f
Zhu, Chunyan
3b539a8b-319a-4662-aa39-7b4eab164acb
Wu, Xuefeng
6925976a-7300-4c4e-912d-e47343bb9f84
Wan, Yuanyang
a3171ce6-a6b5-48e2-b962-23600c94553f
Jay, David
2185e549-4499-4e08-9ec8-16556f039cf2
Townend, Ian
f72e5186-cae8-41fd-8712-d5746f78328e
Wang, Zheng Bing
19bbb87b-d05c-40cf-95b2-679ea098b030
Estuarine, State key laboratory
82a4a0dc-1917-4e65-8739-508ca91007fb
Guo, Leicheng
17e93f75-1537-481e-bba6-c9217b42428f
Zhu, Chunyan
3b539a8b-319a-4662-aa39-7b4eab164acb
Wu, Xuefeng
6925976a-7300-4c4e-912d-e47343bb9f84
Wan, Yuanyang
a3171ce6-a6b5-48e2-b962-23600c94553f
Jay, David
2185e549-4499-4e08-9ec8-16556f039cf2
Townend, Ian
f72e5186-cae8-41fd-8712-d5746f78328e
Wang, Zheng Bing
19bbb87b-d05c-40cf-95b2-679ea098b030
Estuarine, State key laboratory
82a4a0dc-1917-4e65-8739-508ca91007fb

Guo, Leicheng, Zhu, Chunyan, Wu, Xuefeng, Wan, Yuanyang, Jay, David, Townend, Ian, Wang, Zheng Bing and Estuarine, State key laboratory (2020) Strong inland propagation of low‐frequency long waves in river estuaries. Geophysical Research Letters, 47 (19), [e2020GL089112]. (doi:10.1029/2020gl089112).

Record type: Article

Abstract

Tidal waves traveling into estuaries are modified by channel geometry and river flow. The damping effect of river flow on incident astronomical tides is well documented, whereas its impact on low‐frequency tides like MSf and Mm is poorly understood. In this contribution, we employ a numerical model to explore low‐frequency tidal behavior under varying river flow. MSf and Mm are locally generated by frictional mechanisms inside an estuary, and they are larger in amplitude far upstream in tidal rivers and persist landward of the point of tidal extinction. Increasing river flow nonlinearly modulates the longitudinal variations of MSf and Mm amplitudes. This is dynamically explained by flow‐enhanced asymmetry in subtidal friction over the spring‐neap (MSf) and perigee‐apogee (Mm) cycles, respectively. Estuaries act as frequency filters, where low‐frequency waves decay at a smaller rate and propagate more inland than high‐frequency waves. Strong inland penetration of low‐frequency tides informs compound flood management.

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Accepted/In Press date: 22 September 2020
e-pub ahead of print date: 28 September 2020
Published date: 16 October 2020
Keywords: MSf, low-frequency, river discharge, subtidal friction

Identifiers

Local EPrints ID: 445801
URI: http://eprints.soton.ac.uk/id/eprint/445801
ISSN: 0094-8276
PURE UUID: fe4f066a-2b0c-4574-963a-bca38ee5477d
ORCID for Ian Townend: ORCID iD orcid.org/0000-0003-2101-3858

Catalogue record

Date deposited: 07 Jan 2021 17:35
Last modified: 26 Nov 2021 05:43

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Contributors

Author: Leicheng Guo
Author: Chunyan Zhu
Author: Xuefeng Wu
Author: Yuanyang Wan
Author: David Jay
Author: Ian Townend ORCID iD
Author: Zheng Bing Wang
Author: State key laboratory Estuarine

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