The Bahia Blanca estuary: an integrated overview of its geomorphology and dynamics.

PICCOLO M. C.; PERILLO, G. M. E.; MELO, W.D.

Perspectives on integrated coastal zone management in South America.

Instituto Superior Técnico (Portugal)

Lugar: Lisboa; Año: 2008; p. 221 - 231

Bah´ıa Blanca Estuary displays one of the most complex sets of geomorphological and dynamicconditions to be found on the Argentine coastline. There are major differences with thetypical river mouth estuary because of the geological conditions that created this environment.First of all, the estuary is only a part of what once was the largest delta in the country beingalmost 200 km wide at the distal point. During its geological evolution,  it went through full fluvial and subaerial conditions to a shallow bay-shelf with depths up to 7-10 m over the tidal flats today and depths of more than 30 m in the outer reaches of the channels. The Flandrian transgression retreated at a much slower pace than the transgression; the coast moved progressively, leaving sand bars and spits. Although there are no definitive paleontological features that can provide hard evidence, we believe that the climatic conditions during the retreating period were already as dry as the present one. Therefore, very little input of sediment was provided by the rivers coming into the receding bay.Based on the salinity and temperature distribution alone, the Bah´ıa Blanca Estuary is dividedin two. The inner part, from the mouth of the Sauce Chico River to Ingeniero White, is classifiedas a partially mixed estuary during normal runoff conditions, but with a strong tendency tobecome vertically and even sectionally homogeneous during low runoff. The outer part issectionally homogeneous. The boundary between both parts is transitory and depends on theriver discharge. According to the classification of Hansen and Rattray (1966), the estuary maybe characterized as Type la.