Response to channel deepening of the salinity intrusion, estuarine circulation, and stratification in an urbanized estuary
MetadataShow full item record
Modifications for navigation since the late 1800s have increased channel depth (H) in the lower Hudson River estuary by 10–30%, and at the mouth the depth has more than doubled. Observations along the lower estuary show that both salinity and stratification have increased over the past century. Model results comparing predredging bathymetry from the 1860s with modern conditions indicate an increase in the salinity intrusion of about 30%, which is roughly consistent with the H5/3 scaling expected from theory for salt flux dominated by steady exchange. While modifications including a recent deepening project have been concentrated near the mouth, the changes increase salinity and threaten drinking water supplies more than 100 km landward. The deepening has not changed the responses to river discharge (Qr) of the salinity intrusion (~Qr−1/3) or mean stratification (Qr2/3). Surprisingly, the increase in salinity intrusion with channel deepening results in almost no change in the estuarine circulation. This contrasts sharply with local scaling based on local dynamics of an H2 dependence, but it is consistent with a steady state salt balance that allows scaling of the estuarine circulation based on external forcing factors and is independent of depth. In contrast, the observed and modeled increases in stratification are opposite of expectations from the steady state balance, which could be due to reduction in mixing with loss of shallow subtidal regions. Overall, the mean shift in estuarine parameter space due to channel deepening has been modest compared with the monthly‐to‐seasonal variability due to tides and river discharge.
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(7), (2019): 4784-4802, doi: 10.1029/2019JC015006.
Suggested CitationRalston, D. K., & Geyer, W. R. (2019). Response to channel deepening of the salinity intrusion, estuarine circulation, and stratification in an urbanized estuary. Journal of Geophysical Research-Oceans, 124(7), 4784-4802.
Showing items related by title, author, creator and subject.
The transformation of salinity variance : a new approach to quantifying the influence of straining and mixing on estuarine stratification Li, Xiangyu; Geyer, W. Rockwell; Zhu, Jianrong; Wu, Hui (American Meteorological Society, 2018-03-08)The roles of straining and dissipation in controlling stratification are derived analytically using a vertical salinity variance method. Stratification is produced by converting horizontal variance to vertical variance via ...
Scully, Malcolm E.; Geyer, W. Rockwell (American Meteorological Society, 2012-05)Data from the Hudson River estuary demonstrate that the tidal variations in vertical salinity stratification are not consistent with the patterns associated with along-channel tidal straining. These observations result ...
The influence of stratification and nonlocal turbulent production on estuarine turbulence : an assessment of turbulence closure with field observations Scully, Malcolm E.; Geyer, W. Rockwell; Trowbridge, John H. (American Meteorological Society, 2011-01)Field observations of turbulent kinetic energy (TKE), dissipation rate ε, and turbulent length scale demonstrate the impact of both density stratification and nonlocal turbulent production on turbulent momentum flux. The ...