RESULTS Figure 3 depicts time series of water elevation and burst averaged

Results figure 3 depicts time series of water

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RESULTS Figure 3 depicts time series of water elevation and burst- averaged velocity. Temporal breaks around low tide denote times when water levels fall below the height of the pressure transducer. The time series covers four tidal periods, including two low high (LH) and two high high (HH) tides. Along-channel currents are strongest during flood, and maximum speeds precede maximum water elevation. Maximum speeds are stronger during the HH tides, because a larger volume of water must pass through the channel in the same amount of time. Maximum flood currents are higher over the sandbank. Maximum along-channel ebb currents are weaker. The cross-channel current is weaker, but indicates a net lateral circulation on both sides of the channel that varies as a function of bank elevation and tidal stage. During the first two tidal periods, an initial positive cross-channel current (toward the eastern side of the bank) continues until around peak flood. The lateral current then switches direction to flow more along the channel axis or slightly toward the western side of the bank (oyster). During the last two tidal cycles, the same pattern is seen on the eastern (sand) side of the channel, but on the western (oyster) side, the current is directed up the bank throughout flood. The net effect is a slight clockwise rotation of the horizontal current vector around mid-tidal stage when the speeds are strongest. The rotation is related to overtopping of the channel banks, in which the current veers toward the west to flow over the submerged shoal that extends beneath the boardwalk. During ebb, the cross-channel current is highly variable and generally does not indicate a clear trend, except on Figure 3. Time series of the burst-averaged velocity. Water elevation is shown to illustrate corresponding tide stage. Interruption in the time series around low tide denote periods when the water level dips below the height of the sensors. Water elevation is from the pressure sensor deployed on the oyster bank. From hour 0 to hour 24 the ADVs were deployed at the lower elevation on either side of the bank. At hour 24 the sensors were repositioned to the higher locations on the banks. Journal of Coastal Research, Vol. 31, No. 4, 2015 980 Styles
the sandbank during the HH cycles, in which the current is directed up the bank toward the east. This is consistent with the direction of ebb in the system because the cross-channel current flows from the shoal to the west. The lateral current eventually vanishes as ebb continues and water levels fall below the top of the bank. The vertical velocity component at both locations during the first two tidal periods is negative around maximum flood and very weak ( , 2.5 cm s ± 1 ). During the last two tidal periods, current speeds on the oyster bank remain negative but switch sign over the sandbank. This is consistent with a helical flow pattern, with downward flow on the western bank and upward flow on the eastern bank. Like the horizontal components, vertical velocities are highly variable and generally weaker during ebb.

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