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Abstract Despite its relatively small magnitude, cross-channel circulation in estuaries can influence the along-channel momentum balance, dispersion, and transport. We investigate spatial and temporal variation in cross-channel circulation at two contrasting sites in the Hudson River estuary. The two sites differ in the relative strength and direction of Coriolis and curvature forcing. We contrast the patterns and magnitudes of flow at the two sites during varying conditions in stratification driven by tidal amplitude and river discharge. We found well-defined flows during flood tides at both sites, characterized by mainly two-layer structures when the water column was more homogeneous and structures with three or more layers when the water column was more stratified. Ebb tides had generally weaker and less definite flows, except at one site where curvature and Coriolis reinforced each other during spring tide ebbs. Cross-channel currents had similar patterns, but were oppositely directed at the two sites, demonstrating the importance of curvature even in channels with relatively gradual curves. Coriolis and curvature dominated the measured terms in the cross-channel momentum balance. Their combination was generally consistent with driving the observed patterns and directions of flow, but local acceleration and cross-channel advection made some notable contributions. A large residual in the momentum balance indicates that some combination of vertical stress divergence, baroclinic pressure gradients, and along-channel and vertical advection must play an essential role, but data limitations prevented an accurate estimation of these terms. Cross-channel advection affected the along-channel momentum balance at times, with implications for the exchange flow’s strength. Significance StatementCurrents that flow across the channel in an estuary move slower than those flowing along the channel, but they can transport materials and change water properties in important ways, affecting human uses of estuaries such as shipping, aquaculture, and recreation. We wanted to better understand cross-channel currents in the Hudson River estuary. We found that larger tides produced the strongest cross-channel currents with a two-layer pattern, compared to weaker currents with three layers during smaller tides. Higher or lower river flow also affected current strength. Comparing two locations, we saw cross-channel currents moving in opposite directions because of differences in the curvature of the river channel. Our results show how channel curvature and Earth’s rotation combine to produce cross-channel currents.
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This content will become publicly available on March 1, 2026
Specific Momentum and Energy for Flow through a Wide Quasi-Rectangular Channel
Specific energy and momentum are two fundamental quantities to investigate associated water depths, i.e., subcritical and super-critical, for open channel flow passing through wide rectangular channels. Historically, alternative or sequent depths were often used because there were no analytical solutions for flow depths with clear mathematical steps. In this study, we provide primarily detailed derivation procedures of the analytic solutions for the two water depths in specific momentum and energy equations without using symbolic software. More importantly, we found reciprocal relationships between the water depths of the specific energy and momentum and generalized specific energy and momentum equations for the quasi-rectangular channel geometries with varying depths.
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- Award ID(s):
- 2034824
- PAR ID:
- 10581789
- Publisher / Repository:
- Journal of Hydraulic Engineering
- Date Published:
- Journal Name:
- Journal of Hydraulic Engineering
- Volume:
- 151
- Issue:
- 2
- ISSN:
- 0733-9429
- Page Range / eLocation ID:
- 06024013
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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