The intertidal volume of Florida'sIndian River Lagoon

The intertidal volume of Florida's Indian River lagoon is investigated to quantify
the range of values occurring over a one-year period of time, and to determine the nature of this
temporal variability. Intertidal volumes are calculated for the lagoon as a whole, and for three
sub-basins defined by the lagoon's three inlets. A one-year simulation indicates that 38.7 x 10⁶m³
of water enters and leaves the lagoon on an average semidiurnal tidal cycle. The effective intertidal
volume, representing the net exchange, cannot be determined from the historical data base of
salinity. The range of 12.6-71.7 x 10⁶m³ is due more to diurnal inequalities than to differences
between spring and neap tide conditions. The northern part of the lagoon, with 65% of the total
surface area, contributes only 9% of the intertidal volume. The southern part of the lagoon has
18% of the surface area, but it contributes 63% of the intertidal volume. Harmonic analysis shows
that the M₂ constituent is the principal tidal constituent throughout the lagoon. In the northern
segment, semidiural constituents are damped less than diurnal constituents, and the form number
is about 1.5. Elsewhere, the form number is approximately 0.5.