coastal upwelling
64
with erosional features. An important process along many coasts is the
along-shore displacement of sediment by longshore current or, in the breaker
zone, longshore drift. Regression or transgression of the coast is often indicated by
submarine or marine terraces.
coastal upwelling when a drift current transports water away from the coast, the
deficit that occurs will be supplied from deeper layers under the influence of
the pressure gradient that develops. It even is not necessary that the wind
blows offshore: the Ekman transport being at right angles to the wind can also
result in offshore transport when the wind blows more or less parallel to the
coast, if this coast is to the left of the wind in the northern hemisphere or to
the right of the wind in the southern hemisphere. The process of upward
moving water is called upwelling. As the water at greater depth is colder,
upwelling areas are characterized by relatively cold surface water. Upwelling
also carries fresh nutrients into the euphotic zone and therefore promotes the
productivity in these regions. Typical upwelling regions are the coasts of
Morocco and Namibia in the Atlantic Ocean, and the coasts of Chili and
California in the Pacific.
Coastal upwelling. (After
Fairbridge 1966)
coastline, legal aspects for marking the zones landward and seaward, on which
states have certain sovereign rights, the coastline is taken as a base for defining the baseline separating these zones. The normal baseline, according to
UNCLOS III, will be the low-water line (which may be the average low-water line
or the average spring low-water line) along the coast, as marked on largescale charts officially recognized by the coastal state. When the coastline is
deeply indented and cut into, when there is a fringe of islands along the
coast in its immediate vicinity, or the coastline is highly unstable due to the
presence of a delta and other natural conditions, straight baselines may be
drawn, joining appropriate points and following the general direction of the
coast. Straight baselines may also be drawn across the mouth of rivers,
64
with erosional features. An important process along many coasts is the
along-shore displacement of sediment by longshore current or, in the breaker
zone, longshore drift. Regression or transgression of the coast is often indicated by
submarine or marine terraces.
coastal upwelling when a drift current transports water away from the coast, the
deficit that occurs will be supplied from deeper layers under the influence of
the pressure gradient that develops. It even is not necessary that the wind
blows offshore: the Ekman transport being at right angles to the wind can also
result in offshore transport when the wind blows more or less parallel to the
coast, if this coast is to the left of the wind in the northern hemisphere or to
the right of the wind in the southern hemisphere. The process of upward
moving water is called upwelling. As the water at greater depth is colder,
upwelling areas are characterized by relatively cold surface water. Upwelling
also carries fresh nutrients into the euphotic zone and therefore promotes the
productivity in these regions. Typical upwelling regions are the coasts of
Morocco and Namibia in the Atlantic Ocean, and the coasts of Chili and
California in the Pacific.
Coastal upwelling. (After
Fairbridge 1966)
coastline, legal aspects for marking the zones landward and seaward, on which
states have certain sovereign rights, the coastline is taken as a base for defining the baseline separating these zones. The normal baseline, according to
UNCLOS III, will be the low-water line (which may be the average low-water line
or the average spring low-water line) along the coast, as marked on largescale charts officially recognized by the coastal state. When the coastline is
deeply indented and cut into, when there is a fringe of islands along the
coast in its immediate vicinity, or the coastline is highly unstable due to the
presence of a delta and other natural conditions, straight baselines may be
drawn, joining appropriate points and following the general direction of the
coast. Straight baselines may also be drawn across the mouth of rivers,