In an estuarine channel the tidal asymmetry, sediment transport, and morphology are interconnected. To maintain a stable channel, we need to take tidal asymmetry into account. A relationship connecting tidal asymmetry and sediment transport rate has been used to evaluate the relative merits of channel modification through numerical simulations. Two criteria have been identified for ensuring the channel stability: (a) maintaining ebb dominance and (b) minimizing the spatial gradient in the net sediment transport function ⟨q⟩. Using these criteria for a test case, we have evaluated Hooghly estuary (east coast, India), where heavy sedimentation is experienced and a permanent solution is needed. The approach provides better insight into the sedimentation pattern in a semidiurnal tidal process in a shallow estuary with braided channels. Among the factors affecting tidal asymmetry, the relative phase difference (β) between M2 and M4 current constituents has a major influence and is thus responsible for the sedimentation pattern. Through numerical study it was found that a combination of deepened, uniform channel with enhanced ebb flow led to a favorable β, indicating less deposition.
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1 March 2009
Estuarine Channel Stability Assessment through Tidal Asymmetry Parameters
K. M. Sivakholundu,
J. S. Mani,
V. G. Idichandy,
S. Kathiroli
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Journal of Coastal Research
Vol. 2009 • No. 252
March 2009
Vol. 2009 • No. 252
March 2009
ADCIRC
bedload transport
current ellipse
Flood and Ebb dominance
Harmonic constituents
maintenance dredging
overtide