the upstream edge far enough from tidal influence. The freshwater mnoff is imposed as a boundary condition in the 2D model. A relaxation
time is supposed in order to impose heat and salt at the ocean boundaries
from values outside the estuaty, when water enters the estuaty. Both are
directly imposed at the river boundary. Heat and salt fluxes through the
free surface are not considered.
Results and discussion
To calculate the residual current under pristine conditions a ffeshwater input of 18 m
3 .s
4 was considered. A two-kyered residual pattern for the residual circulation can be observed in figure 2a (surface layer) and figure 2b
(bottom layer). Water is observed to leave the estuary through upper layers
and to enter it through bottom layers. A similar circulation pattem was calculated under present conditions, with a freshwater mn-off of 9 mV. A
twokyered residual pattern for the residual circulation was also observed in
this case: figure 2c (surface layer) and figure 2d (bottom layer).
Figure 2 - Residual current calculated for 28 days under pristine conditions: (a) surface
layer, (b) bottom layer and under present conditions (c) surface layer, (d) bottom layer.
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