Phil Duzinski - Institute of Marine and Coastal Science

Estuarine Turbidity Maximum
in Delaware Estuary
Phil Duzinski
Overview of estuary
• Coastal plain estuary,
partially stratified to
well‐mixed salinity
• Mean salt intrusion
97 km from mouth
• 1.3106 mt per year
dredged from ETM
(2.6106 m3 )
Sommerfield, 2010
ETM dynamics
• “Sediment trap” formed by gravitational circulation
where seaward barotropic fresh water river discharge
interacts with landward baroclinic flow from saline
marine water (Schubel, 1968)
• Interactions between density driven buoyancy and
barotropic tidal asymmetries in flood-dominated systems
(Chant & Stoner, 2001)
• Combination of gravitational circulation, tidal asymmetry,
and tidal pumping of salt control location of ETM and
sediment deposition (Sommerfield & Wong, 2011)
• Impacts on biogeochemical and primary productivity
Vertical mixing from tidal asymmetry in
Navesink River, NJ
• Ebb: light water over
heavy – stable
• Flood: heavy water
over light – unstable
Chant and Stoner, 2001
Estuarine Gravitational Circulation
Sommerfield, 2010
Estuarine Turbidity Maximum
Sommerfield, 2010
Impacts of tidal pumping on salinity and null point
• The limit of salt intrusion extends 10‐20 km landward of the null point
and ETM core due to tidal pumping of salt
Sommerfield and Wong, 2011
Variability of Sediment Influx and Turbidity
Sommerfield and Wong, 2011
Chant and Stoner, 2001: Particle trapping in a stratified flood‐dominated estuary,
J. Mar. Res., 59, 29–51.
Gebert, Sommerfield and Walsh, 2013: Sources, sinks and budget of fine grain
sediment in Delaware Estuary, Delaware Science and Environmental Summit,
Cape May, NJ
Delaware Estuary Regional Sediment Management Plan, 2013: Sediment Quantity
and Dynamics White Paper
Schubel, 1968: Turbidity maximum of the northern Chesapeake Bay, Science, 161,
Sommerfield, 2010: Regional Sediment Management Workshop, John Heinz
National Wildlife Refuge, Philadelphia, PA
Sommerfield and Wong, 2011: Mechanisms of sediment flux and turbidity
maintenance in the Delaware Estuary, J. Geophys Res, 116, C01005

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