Sediment transport time scales and trapping efficiency in a tidal river
MetadataShow full item record
Observations and a numerical model are used to characterize sediment transport in the tidal Hudson River. A sediment budget over 11 years including major discharge events indicates the tidal fresh region traps about 40% of the sediment input from the watershed. Sediment input scales with the river discharge cubed, while seaward transport in the tidal river scales linearly, so the tidal river accumulates sediment during the highest discharge events. Sediment pulses associated with discharge events dissipate moving seaward and lag the advection speed of the river by a factor of 1.5 to 3. Idealized model simulations with a range of discharge and settling velocity were used to evaluate the trapping efficiency, transport rate, and mean age of sediment input from the watershed. The seaward transport of suspended sediment scales linearly with discharge but lags the river velocity by a factor that is linear with settling velocity. The lag factor is 30–40 times the settling velocity (mm s−1), so transport speeds vary by orders of magnitude from clay (0.01 mm s−1) to coarse silt (1 mm s−1). Deposition along the tidal river depends strongly on settling velocity, and a simple advection-reaction equation represents the loss due to settling on depositional shoals. The long-term discharge record is used to represent statistically the distribution of transport times, and time scales for settling velocities of 0.1 mm s−1 and 1 mm s−1 range from several months to several years for transport through the tidal river and several years to several decades through the estuary.
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: Earth Surface 122 (2017): 2042–2063, doi:10.1002/2017JF004337.
Suggested CitationArticle: Ralston, David K., Geyer, W. Rockwell, "Sediment transport time scales and trapping efficiency in a tidal river", Journal of Geophysical Research: Earth Surface 122 (2017): 2042–2063, DOI:10.1002/2017JF004337, https://hdl.handle.net/1912/9471
Showing items related by title, author, creator and subject.
Nowacki, Daniel J.; Ogston, Andrea S.; Nittrouer, Charles A.; Fricke, Aaron T.; Van, Pham Dang Tri (John Wiley & Sons, 2015-09-23)A better understanding of flow and sediment dynamics in the lowermost portions of large-tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and ...
How tidal processes impact the transfer of sediment from source to sink : Mekong River collaborative studies Ogston, Andrea S.; Allison, Mead A.; McLachlan, Robin L.; Nowacki, Daniel J.; Stephens, J. Drew (Oceanography Society, 2017-09)Significant sediment transformation and trapping occur along the tidal and estuarine reaches of large rivers, complicating sediment source signals transmitted to the coastal ocean. The collaborative Mekong Tropical Delta ...
Chen, Shih-Nan; Geyer, W. Rockwell; Sherwood, Christopher R.; Ralston, David K. (American Geophysical Union, 2010-10-16)A 3-D hydrodynamic model is used to investigate how different size classes of river-derived sediment are transported, exported and trapped on an idealized, river-dominated tidal flat. The model is composed of a river channel ...