Hydrodynamics
External wave movements
Sea level
Currents in offshore waters
Currents within the port
External wave movements:
The most frequent wave movements around the port (80%) are less than 1 metre high and flow predominantly parallel to the coast. Maximum wave height is about 7 metres. Wave frequency is around 4 seconds.
Wave frequency and height increase during autumn and winter. This trend disappears in summer.
Sea level:
Variations in sea level mean that sheltered waters in the port are filled and emptied. There are two types of tide movements:
-
The astronomical tide, caused by the gravitational effects of the Moon and the Sun, with a maximum range of 0.85 m and a maximum and minimum every 12 hours.
- The meteorological tide, caused by wind and/or atmospheric pressure, ranging between 13 and 98 cm.
Monthly average tide levels are highest in October and November and lowest in February and March.
Currents in offshore waters:
The pattern of currents is characterised by a two-layer structure with respect to the axis parallel to the coast (210°). In the surface layer of water, from 0 to 6 metres deep, the average current is about 0.04 m/s. In the deep layer from 8 to 50 metres down, the current speeds up to about 0.20 m/s. Speeds approaching 0.5 m/s have been observed for periods lasting several days, with a maximum of 0.57 m/s.
Currents within the port:
Inside the port, water movement follows two different patterns depending on the season. In winter there is a general circulation running from the North to the South entrance mouth, with a superficial layer directly influenced by the wind that can be pushed in the opposite direction.
However, in summer no such movement exists between the entrance mouths, with each behaving independently of the other. The vertical structure also changes, with a three-layer structure forming in the entrance mouths and a two-layer structure in the channel between entrance mouths.
