Hydrography of the Russian River Estuary - Sonoma County Water ...

Figure 3.37. Estuary bathymetry from 10m x 10m grid. Segments used for salt balance
calculations and associated CTD station locations are shown.
The change in salinity during the September-October closure is shown Figure 3.38. In
general the outer estuary loses salt and the inner estuary gains salt, resulting from the
baroclinic forcing that moves excess salt from near the mouth and redistributes it so that
isopycnals are level. The pivot point between decrease and increase in salinity is 5 km
from the mouth, over a long shallow ridge between Willow Creek and Sheephouse
Creek. The depth of strongest change is near the pycnocline depth, so that much of the
observed change may be due to relaxation of the tilt in the halocline after closure. The
increase in salinity observed in the outer estuary on 15 September is presumably a
result of the wave overwash event between 12 and 14 September, with some of the
intruding seawater mixing into the pycnocline and spreading landward at this depth.
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