An introduction to the tides of Florida’s Indian River Lagoon. I. Water levels

Water level data collected over a 25-year period of time, and from 23 locations, are
used to characterize the tides of Florida's Indian River lagoon. Diurnal and semi-diurnal tidal
constituent amplitudes decrease rapidly with distance from each of three inlets. Beyond a point
25 km north of Sebastian Inlet, all diurnal and semi-diurnal constituent amplitudes are 1 cm or
less, and tidal period water level variations account for less than 5% of the total variance. South
of Sebastian Inlet, and especially south of Fort Pierce Inlet, tidal amplitudes increase, and the
variance of tidal period water level variations is approximately equal to that of long-period
fluctuations. Fortnightly and monthly constituent amplitudes are all a few centimeters or less.
Semi-annual constituents show considerable variability in amplitude and phase because the data
are from different time periods. The amplitude of the annual variation is consistently about twice
that of the semi-annual variation, however.