The Todos os Santos Bay, located on northeastern Brazil, is the second larg
est coastal bay in the country. after Sao Marcos Bay. The three main draina
ge basins convey an average of 120 m(3)/s of freshwater towards the bay, th
e majority of it, however, held by a dam in Paraguacu River since 1985. The
original average freshwater inflow was two orders of magnitude smaller tha
n the estimated tidal discharge through the main bay entrance, and the ocea
nographic characteristics of the bay, as indicated by bay salinity measurem
ents, are clearly marine. The tides are semi-diurnal, and are amplified up
the bay by a factor of 1.5. Shallow water constituents become more importan
t as the tide propagates along Paraguacu Channel and Paraguacu River, where
they generate time asymmetries that change between spring and neap tides.
Currents in the bay are mainly bi-directional, and are stronger during the
ebbing tide in most of the bay. Offshore, relatively strong tidal currents
appear to be felt in a radius of about 10 km, where they are superimposed o
n winds driven currents orientated to the southwest.