A Method for Quantifying Total Freshwater Input and Flushing Time in Estuaries
Qizhong Guo and George P. Lordi
Journal of Environmental Engineering, July 2000 pp. 675-683
Abstract
A method is developed to quantify total freshwater input and flushing time in
estuaries using measured flow and salinity data at the estuary-ocean
boundary. A formula is derived to calculate the volume of mixed estuarine water
that leaves the estuary on the ebb tide. The calculated volume of mixed
estuarine water, along with the volume of new ocean water that enters the
estuary on the flood tide, is used to quantify the total volume of freshwater
input. The calculated volume of mixed estuarine water is also used to
quantify the flushing time. The developed method is applied to Barnegat
Bay, N.J. The volume of freshwater input calculated from the new method compares
well with that estimated using watershed, aquifer, and meteorological
data. The flushing time calculated from the new method is between that
calculated from the classical tidal prism method and that from the fraction of
freshwater method. An assessment is made on the sensitivity of calculated
values to the quality of measured data at the estuary-ocean boundary. The
volume of freshwater input and the flushing time calculated from the developed
method are highly reliable when there is a significant salinity difference
between flood and ebb tides.
