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In this idealised experiment, an estuarine circulation is simulated,
mainly in order to demonstrate how to use tracer advection and
internal pressure gradients in GOTM, but also to show the basic
physical process of tidal asymmetries and its impact on SPM dynamics.

The average water depth is H=15 m, the model is run for 10 days.
The forcing is a M2 tide (of period 44714 s) which prescribes
sinusoidal time series for the vertically averaged momentum in
west-east direction with an amplitude of 1.5 m/s and an offset
of 0.05 m/s directed to the west in order to simulate river
run-off.  The surface elevation is sinusoidal as well with an
amplitude of 1 m and a phase shift of 1.5 hours compared to the
velocity.  A constant in time and space horizontal west-east salinity
gradient of -0.0005 ppt/m is prescribed, advection of salinity
is turned on. In order not to obtain negative salinities, relaxation
to the initial salinity profile of 15 ppt is made.  In order to avoid
strong stratification near the surface, a small wind stress of 0.01027
N/m^2 is applied.

A simple suspended matter equation with constant settling velocity is
calculated in order to show the effect of tidal asymmetries on SPM
transport. It is clearly seen that during flood SPM is mixed higher up into
the water column than during ebb, an effect which has been described
by Geyer 1993.

For further information have a look into the GOTM documentation,
in subsection 'Estuarine dynamics' of the GOTM scenarios section.