FLUVIAL REGIME OF THE UPPER PARAÍBA RIVER IN THE SEMIARID REGION OF PARAIBA STATE

Abstract

The upper course of the Paraíba River drains one of Brazil's driest regions. Since April 2017, the Paraíba River has been receiving water from the transposition of the São Francisco River, altering the natural characteristics of the river regime. The aim of this study was therefore to analyze the fluvial regime of the upper Paraíba River before the arrival of the waters of the São Francisco River. To this end, historical rainfall and flow data were obtained from the ANA's HIDROWEB system (2018), and the volumes of the reservoirs were consulted through AESA (2019). Statistical treatments were applied in order to characterize the river regime and its relationship with rainfall distribution. The results showed that February, March and April are the months with the highest flows. On average there are 134 days with flow in the year and there is a downward trend in the number of days with flow. The river regime is 2 to 4 months, marked by short-lived floods. Weirs have a strong influence on the flow regime. The upper Paraíba River shows hydrological behavior typical of dryland rivers, marked by the spatio-temporal variability of river dynamics and the disconnection of hydrosedimentological flow throughout the basin.