TY - JOUR
T1 - Wave Generation, Dissipation, and Disequilibrium in an Embayment With Complex Bathymetry
AU - Chen, Jia Lin
AU - Ralston, David K.
AU - Geyer, W. Rockwell
AU - Sommerfield, Christopher K.
AU - Chant, Robert J.
N1 - Funding Information:
Funding was provided by National Science Foundation Coastal SEES: Toward Sustainable Urban Estuaries in the Anthropocene (OCE 1325136) and Ministry of Science and Technology (MOST 107-2611-M-006-004). We thank James Kirby, Fengyan Shi, and the two anonymous reviewers for their careful reading of our manuscript and their insightful comments. We thank Tracy Quirk for providing wave measurements in Bombay Hook, DE and Stow Creek, NJ. We thank Katie Pijanowski for compiling historical and modern bathymetric data for the estuary. Data supporting this study are posted to Zenodo (http://doi.org/10.5281/zenodo.1433055).
Funding Information:
Funding was provided by National Science Foundation Coastal SEES: Toward Sustainable Urban Estuaries in the Anthropocene (OCE 1325136) and Ministry of Science and Technology (MOST 107-2611-M-006-004). We thank James Kirby, Fengyan Shi, and the two anonymous reviewers for their careful reading of our manuscript and their insightful comments. We thank Tracy Quirk for providing wave measurements in Bombay Hook, DE and Stow Creek, NJ. We thank Katie Pijanowski for compiling historical and modern bathymetric data for the estuary. Data supporting this study are posted to Zenodo (http://doi.org/ 10.5281/zenodo.1433055).
Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
PY - 2018/11
Y1 - 2018/11
N2 - Heterogeneous, sharply varying bathymetry is common in estuaries and embayments, and complex interactions between the bathymetry and wave processes fundamentally alter the distribution of wave energy. The mechanisms that control the generation and dissipation of wind waves in an embayment with heterogeneous, sharply varying bathymetry are evaluated with an observational and numerical study of the Delaware Estuary. Waves in the lower bay depend on both local wind forcing and remote wave forcing from offshore, but elsewhere in the estuary waves are controlled by the local winds and the response of the wavefield to bathymetric variability. Differences in the wavefield with wind direction highlight the impacts of heterogeneous bathymetry and limited fetch. Under the typical winter northwest wind conditions waves are fetch-limited in the middle estuary and reach equilibrium with local water depth only in the lower bay. During southerly wind conditions typical of storms, wave energy is near equilibrium in the lower bay, and midestuary waves are attenuated by the combination of whitecapping and bottom friction, particularly over the steep, longitudinal shoals. Although the energy dissipation due to bottom friction is generally small relative to whitecapping, it becomes significant where the waves shoal abruptly due to steep bottom topography. In contrast, directional spreading keeps wave heights in the main channel significantly less than local equilibrium. The wave disequilibrium in the deep navigational channel explains why the marked increase in depth by dredging of the modern channel has had little impact on wave conditions.
AB - Heterogeneous, sharply varying bathymetry is common in estuaries and embayments, and complex interactions between the bathymetry and wave processes fundamentally alter the distribution of wave energy. The mechanisms that control the generation and dissipation of wind waves in an embayment with heterogeneous, sharply varying bathymetry are evaluated with an observational and numerical study of the Delaware Estuary. Waves in the lower bay depend on both local wind forcing and remote wave forcing from offshore, but elsewhere in the estuary waves are controlled by the local winds and the response of the wavefield to bathymetric variability. Differences in the wavefield with wind direction highlight the impacts of heterogeneous bathymetry and limited fetch. Under the typical winter northwest wind conditions waves are fetch-limited in the middle estuary and reach equilibrium with local water depth only in the lower bay. During southerly wind conditions typical of storms, wave energy is near equilibrium in the lower bay, and midestuary waves are attenuated by the combination of whitecapping and bottom friction, particularly over the steep, longitudinal shoals. Although the energy dissipation due to bottom friction is generally small relative to whitecapping, it becomes significant where the waves shoal abruptly due to steep bottom topography. In contrast, directional spreading keeps wave heights in the main channel significantly less than local equilibrium. The wave disequilibrium in the deep navigational channel explains why the marked increase in depth by dredging of the modern channel has had little impact on wave conditions.
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U2 - 10.1029/2018JC014381
DO - 10.1029/2018JC014381
M3 - Article
AN - SCOPUS:85056130416
VL - 123
SP - 7856
EP - 7876
JO - Journal of Geophysical Research: Oceans
JF - Journal of Geophysical Research: Oceans
SN - 2169-9291
IS - 11
ER -