Bed Sediment Characteristics in the Paraná and Paraguay Rivers

Abstract

ABSTRACT This paper presents a granulometric characterization of the Paraná and Paraguay rivers bed sediments. Samples obtained along 2,900 km of the thalweg of those rivers form the basis of this study. The main results and other features of the study are as follows: a) the bed sediment of both rivers is composed mainly of medium to fine well-sorted sands, with sizes in the Paraná slightly higher than those in the Paraguay river; b) the variations of mean diameters for both rivers are well correlated with the energy slopes. The correlation coefficient in the Paraguay river increases notably if the discharge and width/depth relationship variations along the channel are included in the regression; and, c) the origin of the transported sands could be related to the geologic characteristics of the Paraná river basin. An explanation is also suggested for the different bed sediment texture found in the Paraná de las Palmas and Paraná Guazú rivers in the lower delta. The explanation is based on the geomorphic processes that built that region of the Paraná river.