The Summer Buoyancy Dynamics of a Shallow Mediterranean Estuary and Some Effects of Changing Bathymetry: Tomales Bay, California

A numerical study is presented of the summer buoyancy dynamics of Tomales Bay (California, U.S.A.) which is an example of a shallow mediterranean estuary. Tomales Bay lies along the line of the San Andreas fault, and the resultant unidirectionality of the estuary greatly simplifies its hydrodynamics. The numerical model hindcasts the temperature and salinity of Tomales Bay from 1987 to 1993 using detailed hydrological and meteorological data, and the results are compared with field observations made during that 7-year period. A second simulation is made over the same 7-year period but using the bathymetry for 1861 when the estuary was longer and deeper. This allows an analysis to be made of the effects on the summer buoyancy dynamics of anthropogenic bathymetry changes. The model predicts that the historical estuary experienced greater negative buoyancy inputs during the late summer periods, and became more inverse with faster dispersion near the head of the basin.