Variações em índices de estabilidade da água em reservatório sob condição de seca acentuada do trópico semiárido brasileiro

Abstract

In arid and semi-arid regions, it’s common to capture and store water for later use in surface reservoirs. These reservoirs serve as the main source of water during times of drought. The semi-arid climate enhances the process of water salinization, which is one of the main water quality issues faced in reservoirs located in these regions. The ionic quality of the surface waters of the Ceará reservoir Sítios Novos was evaluated by calculating the water stability indices. The water quality data of this reservoir were analyzed for the period from 2004-2017. The influence of annual climatic cycle and the time variation of the Langelier Saturation, Ryznar Stability, Larson-Skold, Puckorius and Aggressiveness indexes were determined. The results showed sodium chloride waters, evidently caused by the influence of the local lithology and the proximity to the ocean. There was corrosive potential as indicated by most water stability indices. The rainy and dry seasons didn’t present statistically significant influences on the indexes evaluated, although the deterioration of the water quality in the drought period is perceptible in the computation of these indices. It’s concluded that the evaluation of the superficial waters of the Semi-Arid Tropic through water stability indices is an excellent tool for the management of the quality of these resources, indicating possible limitations of end uses and guiding preventive and corrective measures.