In this study we modelled sea temperature (T ), salinity (S) and density field
dynamics using a 3D numerical model applied to Rijeka Bay (Croatia) in order
to explore their effect on effluent plume dynamics in the vicinity of four submarine
sewage outfalls when the bora wind (NE direction) is blowing. The vertical density
stratification in the area studied is strongly related to the bora wind, which
contributes significantly to the lowering of the pycnocline depth through enhanced mixing in the vertical, giving rise to changes in the neutral buoyancy level. The
features of near-field plume dynamics were calculated with the use of a separate
near-field numerical model, using information on the vertical density distribution
previously calculated using a 3D numerical model.
The results of the numerical simulations and statistical analysis of the wind
data indicate a very low probability of complete water column homogenization and
consequent effluent plume rise to the sea surface under the influence of the bora
wind during the peak tourist season (May–September)