Geomophologic and physical characteristics of a human impacted estuary: Quequen Grande River Estaury, Argentina

PERILLO G.M.E.; PEREZ D.E.; PICCOLO M.C.; PALMA E.D.; CUADRADO D.G

ESTUARINE COASTAL AND SHELF SCIENCE

Elsevier

Año: 2005 vol. 62 p. 301 - 312

0272-7714

Even though the Queque´ n Grande River Estuary has economic and strategic importance from an oceanographic point of view, it has been ignored until recently. Nevertheless, many anthropogenic modi.cations (i.e., dredging, jetty and harbour construction, etc.) have taken place in the last 100 years which, most of them, have resulted in signi.cative economic expenses to the harbour and city authorities due to the lack of adequate prior studies. The purpose of this article is to provide a review of the present status of the geomorphology and main physical characteristics of the estuary and describe the e.ects of these man-made modi.cations upon the estuary. Data were gathered in several .eld cruises from 1994 to 2000 plus from continuous recording devices installed at or near the estuary directed to de.ne the present geomorphologic and oceanographic conditions of the estuary and to establish a monitoring program. The ultimate goal is to provide some practical solutions in diminishing the maintenance of the harbour and to provide pollution-control devices. The estuary is classi.ed as a microtidal, primary, coastal-plain system. It can be considered as a partly-mixed system 2 km from the mouth up to its head (15 km inland). Arti.cial dredging to accommodate the Queque´ n harbour in the last 2 km of the estuary has induced a highly strati.ed water column where the upper 2–3 m concentrates low salinity water and the lower layer is .lled by water of the same or slightly higher salinity than the inner shelf waters. Due to the presence of a step at the head of the harbour, water circulation is very reduced and in some cases nonexistent, producing strong reductive and even anoxic conditions. The foot of the step is a sediment and organic matter trap that must be dredged periodically to insure adequate navigability.