Morphological features in the macrotidal estuary of Río Gallegos, Argentina.

GINSBERG S.S.; MELO, WALTER DANIEL; PERILLO G.M.E.

Bahía Blanca

Encuentro; 4th OPEN SCIENCE MEETING. Land Ocean Interactions in the Coastal Zone; 1999

Instituto Argentino de Oceanografía

Rio Gallegos estuary is located in the south of Santa Cruz province, Argentina. The Gallegos River at the west and the Chico River at the southwest are the tributaries. The estuary is 47km long and its width is 5 km at the mouth, between Punta Loyola and Punta Bustamante. This width continues along 30 km until the Killik Aike Sur farm. After that, it begins abruptly close to the Guer Aike place. Rio Gallegos is a macrotidal estuary, and its mean tidal range is between 12 and 14 meters. This tidal range is considered one of the biggest in the world. Extensive tidal flats within estuarine zones are often associated with major river discharges of sediments. However, in Rio Gallegos estuary, the tidal flats are well-developed, although the input of sediment associated with rivers is negligible. At present the tidal flat sediment comes from erosion of the cliffs that skirt the north coast. The estuary is formed by a series of intertidal banks with widely varying dimensions that forms a complex pattern. Results show a highly variable morphology where the tidal flats and banks are being reworked, inducing continual changes in the estuary. Field studies were undertaken to define the morphology and physical conditions that characterise Rio Gallegos estuary. Although considerable studies have been done along the estuary, virtually no information exists on the general characteristics of the subtidal zone. Therefore, this paper deals with one aspect that has not previously studied, the processes affecting the dynamics and behaviour of the banks.