CHAPTER 1 • Geomorphology and Physical Oceanography of South American Estuaries
3
Fig. 1.2. Morphogenetic classification of estuaries (modified
from Perillo 1995b)
PRIMARY ESTUARIES
Former fl uvial valleys
Coastal Plain
Former glacial valleys
Fjord U ~.' ~/'
OO~
~~' ~
River-influenced
SECONDARY ESTUARIES
Coastal lagoons
Choked
~
Shorr-inler
• Fjards occupy glacially formed troughs in low relief coasts. Examples are those
formed in the northern coast of Sweden.
River-Influenced. In high discharge rivers like the Amazon (Brazil), Mississippi (USA)
and Rio de la Plata (Argentina-Uruguay) the valley is not presently drowned by the
sea. However, the circulation in the lower portions of the river is highly affected by
tidal dynamics, including reversing currents, resulting in characteristic, tidal-dominated morphological patterns. They have been divided in two subcategories:
• Tidal River Estuaries include those rivers that are affected by tidal action but salt
intrusion may be limited to the mouth or it is totally absent within the valley. Nor-
3
Fig. 1.2. Morphogenetic classification of estuaries (modified
from Perillo 1995b)
PRIMARY ESTUARIES
Former fl uvial valleys
Coastal Plain
Former glacial valleys
Fjord U ~.' ~/'
OO~
~~' ~
River-influenced
SECONDARY ESTUARIES
Coastal lagoons
Choked
~
Shorr-inler
• Fjards occupy glacially formed troughs in low relief coasts. Examples are those
formed in the northern coast of Sweden.
River-Influenced. In high discharge rivers like the Amazon (Brazil), Mississippi (USA)
and Rio de la Plata (Argentina-Uruguay) the valley is not presently drowned by the
sea. However, the circulation in the lower portions of the river is highly affected by
tidal dynamics, including reversing currents, resulting in characteristic, tidal-dominated morphological patterns. They have been divided in two subcategories:
• Tidal River Estuaries include those rivers that are affected by tidal action but salt
intrusion may be limited to the mouth or it is totally absent within the valley. Nor-