Salt wedge dynamics lead to enhanced sediment trapping within side embayments in high-energy estuaries
Woodruff, Jonathan D.
Ralston, David K.
MacDonald, Daniel G.
Jones, David S.
MetadataShow full item record
Off-river coves and embayments provide accommodation space for sediment accumulation, particularly for sandy estuaries where high energy in the main channel prevents significant long-term storage of fine-grained material. Seasonal sediment inputs to Hamburg Cove in the Connecticut River estuary (USA) were monitored to understand the timing and mechanisms for sediment storage there. Unlike in freshwater tidal coves, sediment was primarily trapped here during periods of low discharge, when the salinity intrusion extended upriver to the cove entrance. During periods of low discharge and high sediment accumulation, deposited sediment displayed geochemical signatures consistent with a marine source. Numerical simulations reveal that low discharge conditions provide several important characteristics that maximize sediment trapping. First, these conditions allow the estuarine turbidity maximum (ETM) to be located in the vicinity of the cove entrance, which increases sediment concentrations during flood tide. Second, the saltier water in the main channel can enter the cove as a density current, enhancing near-bed velocities and resuspending sediment, providing an efficient delivery mechanism. Finally, higher salinity water accumulates in the deep basin of the cove, creating a stratified region that becomes decoupled from ebb currents, promoting retention of sediment in the cove. This process of estuarine-enhanced sediment accumulation in off-river coves will likely extend upriver during future sea level rise.
Author Posting. © American Geophysical Union, 2017. 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 122 (2017): 2226–2242, doi:10.1002/2016JC012595.
Suggested CitationJournal of Geophysical Research: Oceans 122 (2017): 2226–2242
Showing items related by title, author, creator and subject.
Bathymetric controls on sediment transport in the Hudson River estuary : lateral asymmetry and frontal trapping Ralston, David K.; Geyer, W. Rockwell; Warner, John C. (American Geophysical Union, 2012-10-17)Analyses of field observations and numerical model results have identified that sediment transport in the Hudson River estuary is laterally segregated between channel and shoals, features frontal trapping at multiple ...
Lateral circulation and sediment transport driven by axial winds in an idealized, partially mixed estuary Chen, Shih-Nan; Sanford, Lawrence P.; Ralston, David K. (American Geophysical Union, 2009-12-03)A 3D hydrodynamic model (ROMS) is used to investigate lateral circulation in a partially mixed estuary driven by axial wind events and to explore the associated transport of sediments. The channel is straight with a ...
Sediment transport due to extreme events : the Hudson River estuary after tropical storms Irene and Lee Ralston, David K.; Warner, John C.; Geyer, W. Rockwell; Wall, Gary R. (John Wiley & Sons, 2013-10-18)Tropical Storms Irene and Lee in 2011 produced intense precipitation and flooding in the U.S. Northeast, including the Hudson River watershed. Sediment input to the Hudson River was approximately 2.7 megaton, about 5 times ...