Características geomorfológicas do canal do rio Paraná nas proximidades da barragem de Porto Primavera: variação temporal e espacial dos sedimentos suspensos, de fundo e de algumas variáveis limnológicas.

Abstract

The objective of this study was to characterize the spatial and temporal behavior of flow velocity, depth and sediment transport in a river section located 6km downstream of the Sérgio Motta HPP. To this end, monthly campaigns were carried out in the period between Feb. 2000 to Feb. 2001, at four points in a single-channel section, transverse to the flow of the current. Water samples were collected for suspended sediments, bottom sediment collections, water transparency readings, flow velocity and flow channel depth readings. The results showed that the depth and velocity of flow are under the control of the dam and lock operation. The suspended load was very low (mean of 0.1mg/l), being higher at the marginal points; which may indicate the incorporation of sediments by erosion of the margins by the force of edge friction. There was no strong correlation between suspended sediments and transparency; evidencing that other factors such as organisms; dissolved salts and humic acids have a seasonal influence on the aquatic system. The bottom load data show that the channel is in the process of total removal of sediments from the bed because it is close to the dam, generating a new base level; initiating the process of bed erosion. The change in the flow regime caused by the operation of the HPP had the following consequences: the alteration of the biota; navigability conditions and the frequency of flood pulses in the plain adjacent to the right bank of the drainage channel. To mitigate the environmental impacts generated by the construction of the dam, actions such as the construction of the elevator for aquatic organisms and fish ladder were established.