Impactos hidrofísicos na bacia hidrográfica do alto curso do Rio Paraíba frente a sua perenização

Abstract

The transposition of the São Francisco River and perenization to its east axis, in which the Paraiba River forms part, is a governmental measure to combat drought, which also generates a much wider discussion about the direct and indirect impacts to the river system. Due to the lack of studies about the possible degradation by reception of São Francisco River waters, this work proposes an analysis, based on hydrographic basin framework, of hydrosedimentological or hydrophysical impacts, which the main course of the Paraíba River has suffered. The procedures performed in field work for the analysis proposals consisted of data collection on the topography and velocity data of the previously selected stretches, based on the River Styles characterization previously performed by Santos (2017) in this study area. There were used precipitation and flow data to confirm river behavior and changes, as well as satellite images and recorded photos during different dates of field visit. Considering the complexity of evaluating river processes, the results indicated different processes of hydrosedimentological nature in the basin, indicating a modification in the sedimentological balance, due to the attempt to adept the intermittent channels to the new, perennial regime. In the evaluated points, it was possible to observe evidences of differing of geomorphological nature processes in the channel, such as the formation of islands by expansion of sand bars and stabilization due to vegetation, besides deflection of water mass by antropic obstruction of its flow, lateral and vertical erosion. Interpreting the data, possible evolutionary scenarios were inferred considering the prolongation of the modifications in the analyzed points and in downstream sections, indicating high and constant sedimentation rates, being able to indicate silting and loss of useful life of the reservoirs downstream, as well as stream capacity and competence of the main channel.