Characterization of bottom sediments in the Río de la Plata estuary

DIEGO MOREIRA; CLAUDIA G. SIMIONATO

Montevideo

Conferencia; INTERNATIONAL COHESIVE SEDIMENT DYNAMICS MEETINGS (INTERCOH); 2017

Universidad de la República

Draining the second largest basin of South America, the Río de la Plata (RdP) is one of the largest and most turbid estuaries of the world. Its fresh water plume impacts the properties of the shelf for more than 500 km. The sediments? load that reach the system mainly come from the Paraná river (in its two main branches, Paraná de las Palmas and Paraná Guazú), and has been between 80 and 160 Mtonsy -1 (Urien 1972, Menéndez and Sarubbi, 2007). From that total, 10% correspond to bed load (sand and silt) and 90% to suspended matter (fine silt and clay). The deposits go from sand on the upper estuary and silts in the intermediate estuary, to clay and silts in its exterior part. In the area of the salt wedge, where the river waters meet the sea waters, the flocculation of suspended sediments occurs and, therefore, a zone of maximum turbidity occurs. Turbulence over the bottom, due to tidal currents, waves or winds, can be strong enough to mix and homogenize the water column, and resuspend the sediments. The aim of this work is to characterize the bottom surficial sediments mean distribution and to study their composition including the organic matter and water contents, to obtain a qualitative description of the mean transports.