Over 97% of the water discharge to the Rio de la Plata is provided by the Uruguay river(4600-5300 m³s−1) and Parana river, formed by two tributaries, Paraná Guazú and Paraná de las Palmas, discharging between 17,000 and 21.700 m³s−1; the latter remains constrained along the straight edge of the southern shore (called Franja Costera Sur) of the Rio de la Plata