HEADING PAGE - port of ploce authority * welcome

ENVIRONMENTAL IMPACT STUDY
Rn: 03-033 CONTAINER TERMINAL PLOCE PAGE: 15
A.3.4.1.2 Mareographic data (dynamics of water masses, waves, tides, submarine
springs)
Part of the sea dynamics interesting for mutual impact of the project and sea
movements are certainly tides and sea currents. They will, therefore, be
described here on the basis of existing data.
Tides
The dynamics of exchange of sea levels has the character of semidiurnal
period predominantly on a greater part of the Adriatic and consequently in the
area of the location under consideration.
The theory of sea tides in the Adriatic shows that the distribution of theoretical
amplitudes of longitudinal oscillations coincides with the observation in the
case when assumed that the stimulus for oscillation comes from the Ionian
Sea. On the other hand, the determination of mentioned values does not
agree with empirical values, if these are derived under the condition that the
Adriatic water mass is stimulated to oscillation only by the direct gravitational
action of the moon and the sun. It can be concluded from this that the tides in
the Adriatic sea are not independent.
Almost completely regular flow of the tides is disturbed by fluctuations of the
Adriatic level which is the consequence of the effect of atmosphere, from air
pressure variations and wind action. Increase of the air pressure and northerly
winds (bora/north-easter, sjevernjak/north wind) lower the water level of the
sea in the northern part by 40 cm, while the air pressure drop and southerly
winds (jugo, oštro) which are the consequence of the Mediterranean
depressions (cyclones), increase the water level by 70 cm. Jugo blows
towards the closed part of the basin for several days with the constant
strength and accumulates water in the north Adriatic where, in the period of
high water, the coastal areas can be flooded (very high water level in Trieste
and Venice). On the other hand, very low water levels are linked with high air
pressure which is the consequence of anticyclone over the central Europe.
Fluctuations of the Adriatic water level which is reduced to the action of
mentioned atmospheric factors, consists primarily in slow rising and falling of
its mean level. It is very irregular and slightly disrupts the amplitude of sea tide
oscillations. In addition to that, free oscillations (standing waves) occur, with
periods smaller than 1 minute and up to a period of several hours, which can
sometimes significantly disrupt the rate of sea tides. These are the standing
waves in numerous bays and channels, whose water mass is prompted to
oscillation by impulses of the movement of the atmosphere or of the open sea.
Since their periods depend on dimensions and relief of the basin bed, these
oscillations too are the characteristic of sea delevelling in a particular area. To
date explorations were made of seiches in the bay of Trieste, Bakar and
Kaštela and the free oscillation of the entire Adriatic basin, whose period
amounts to about 23 hours.
RIJEKAPROJEKT d.o.o.