Variations in the Flow of the Santo Antônio River, Relation with the Pantanal Marimbus and the Importance for Biodiversity in the Chapada Diamantina/BA National Park Region

Abstract

The Santo Antônio river is a tributary of the Paraguaçu river and forms, in its low course, a flooded area called Marimbus. There are reports that the flow of this river is being reduced. In this work, a qualitative and quantitative analysis of the flow variation (ΔQ) in the Santo Antônio river was carried out over 58 years, with data from a fluviometric station in Andaraí. The data were systematized and analyzed using Pearson correlations, comparing them with the variation in rainfall (ΔP) in a meteorological station in the sub-basin. The values of DQ between the 1950s and 1970s showed amplitudes ranging from -0.8036 to 4.8386, with 57.92% of the DQ records <0. Between the 1980s and 2018, DQ ranged from -0, 9591 to 2.5644, with 74.31% of the DQ records <0. The comparison DQ and DP between 1950 and 2018 proved to be statistically significant (r = 0.341; R² = 0.1163; p = 0.0116). The data showed a reduction in the river flow correlated mainly with the rainfall variation. Bibliographic data showed an increase in the area occupied by crops that make intensive use of river water, such as bananas. A review of the published bibliography on Marimbus shows five botanical works in the region. There are, also, seven species and a subfamily of fish endemic to the region and neighboring areas. The local fauna is different from what exists in the surrounding regions. Thus, it is necessary that the water intake from the Santo Antônio river be managed to prevent the flow of this watercourse from continuing to decrease.