Massachusetts Bay Circulation and Effluent Modeling

Understanding the circulation of water in Massachusetts and Cape Cod Bays is of
critical importance for determining how nutrients, sediment, contaminants and
other water-borne materials are transported. Numerical circulation models
represent a powerful tool to build understanding of transport processes in
these bays, as well as for synthesis, scenario testing and prediction. The U.S.
Geological Survey has developed a three-dimensional model of circulation in
Massachusetts Bay driven by tides, wind, river runoff, surface heating and
cooling and remote forcing from the Gulf of Maine. The circulation calculated
from this model was used as input to the HydroQual water quality model.

The USGS is currently using the model in a Regional Marine Research Program in
the Gulf of Maine funded study of sources, transport and nutrient environment
of red tide populations in the western gulf. Together with investigators from
WHOI and UNH, this work seeks to characterize the physical transport mechanisms
that influence the distribution and fate of toxic Alexandrium cells in this
region, and the processes by which cells are transported to Massachusetts Bay.
The ability of the regional model to represent the movement of fresh water from
the Kennebec and Androscoggin rivers will be determined.

Over the next three years, the USGS will be developing a regional sediment
transport model by interfacing existing surface wave, bottom boundary layer and
sediment erosion models into the current hydrodynamic model. Current and
suspended sediment data from the long-term mooring (as well as other sites)
will be used for calibration and verification.

When the new outfall comes online, additional hydrodynamic model runs in
Massachusetts Bay will be performed to test the ability of the model to
simulate the effects of the relocated effluent discharge.