TY - JOUR
T1 - Sediment Budget Estimates for a Highly Impacted Embayment with Extensive Wetland Loss
AU - Chant, Robert J.
AU - Ralston, David K.
AU - Ganju, Neil K.
AU - Pianca, Cassia
AU - Simonson, Amy E.
AU - Cartwright, Richard A.
N1 - Publisher Copyright:
© 2020, Coastal and Estuarine Research Federation.
PY - 2021/5
Y1 - 2021/5
N2 - External sediment supply is an important control on wetland morphology and vulnerability to storms, sea-level rise, and land use change. Constraining sediment supply and net budgets is difficult due to multiple timescales of variability in hydrodynamic forcing and suspended sediment concentrations, as well as the fundamental limitations of measurement and modeling technologies. We used two independent observational campaigns and one hydrodynamic modeling effort to estimate the sediment supply to Jamaica Bay, New York, USA, an urbanized embayment with a history of extensive wetland loss. We found that all three estimates indicate a net import to the system, ranging from 36 to 74 kt/year, with a mean estimate of 55 kt/year ± 31 kt/year, which is consistent with a prior estimate derived from radionuclide tracers. Net sediment import is controlled by flood-ebb asymmetry in bed shear stress, which results in higher suspended sediment concentrations on flood tide relative to ebb. This indicates a seaward source of sediment that is resuspended by waves in the coastal ocean, likely offshore marine deposits or potentially from the adjacent Hudson River estuary. Despite the net sediment import, a simple sediment budget suggests that the rate of supply is not sufficient to maintain the present geomorphic planform of the system relative to sea-level rise. The convergent estimates from independent methods provide reasonable guidance as context for sediment-based restoration efforts.
AB - External sediment supply is an important control on wetland morphology and vulnerability to storms, sea-level rise, and land use change. Constraining sediment supply and net budgets is difficult due to multiple timescales of variability in hydrodynamic forcing and suspended sediment concentrations, as well as the fundamental limitations of measurement and modeling technologies. We used two independent observational campaigns and one hydrodynamic modeling effort to estimate the sediment supply to Jamaica Bay, New York, USA, an urbanized embayment with a history of extensive wetland loss. We found that all three estimates indicate a net import to the system, ranging from 36 to 74 kt/year, with a mean estimate of 55 kt/year ± 31 kt/year, which is consistent with a prior estimate derived from radionuclide tracers. Net sediment import is controlled by flood-ebb asymmetry in bed shear stress, which results in higher suspended sediment concentrations on flood tide relative to ebb. This indicates a seaward source of sediment that is resuspended by waves in the coastal ocean, likely offshore marine deposits or potentially from the adjacent Hudson River estuary. Despite the net sediment import, a simple sediment budget suggests that the rate of supply is not sufficient to maintain the present geomorphic planform of the system relative to sea-level rise. The convergent estimates from independent methods provide reasonable guidance as context for sediment-based restoration efforts.
KW - Estuarine dynamics
KW - Human impacted coastal
KW - Sediment transport
KW - Systems
KW - Wetland loss
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U2 - 10.1007/s12237-020-00784-3
DO - 10.1007/s12237-020-00784-3
M3 - Article
AN - SCOPUS:85087358687
SN - 1559-2723
VL - 44
SP - 608
EP - 626
JO - Estuaries and Coasts
JF - Estuaries and Coasts
IS - 3
ER -