Selection of variables in the definition of a water quality index for the Brazilian Federal District

Abstract

Water Quality Indices (WQIs) are based on a small number of variables that establish categories for water quality. This method presents some problems with the evaluations, since WQIs do not consider the multiple uses of the water or differences in regional characteristics. The present study proposes a regional and more appropriate variable group for the definition of a Water Quality Index for the Brazilian Federal District, based on water quality monitoring of surface waters in the region. The monitoring was carried out monthly between August 2016 and July 2017, at three points on the Jardim River, Sobradinho Stream and Sarandi Stream, where 21 variables were evaluated. Among physical-chemical and microbiological analyses, the regional characteristics of these water bodies were noted, as well as their differences, and the main anthropogenic interferences that generate changes in water quality. In the urban area, the disposal of treated sewage from the wastewater treatment plant of Sobradinho was highlighted as the main anthropic interference, and agricultural activities stood out in the rural region of the study area. The impacts in the urbanized area were of greater weight. Thus, based on the results of the Principal Component Analysis (PCA), two groups of variables were selected, one representative of urban areas and the other of rural areas, to compose two probable water quality indices (WQIs) for the Federal District.

Parâmetros significativos para monitoramento e avaliação da qualidade da água, Bacia Hidrográfica do Rio Cachoeira (Joinville, Santa Catarina, Brasil)

“…Um estudo conduzido na região central do país (Distrito Federal, Brasil) indicou, entre outras análises, que OD, coliformes e fósforo podem ser utilizadas como variáveis significativas. Ao longo de três rios avaliados (Rio Jardim, Córrego Sobradinho e Córrego Sarandi), foi verificado que a aplicação de indicadores de forma regionalizada poderá auxiliar no gerenciamento dos recursos hídricos (Passos et al, 2019).…”

Condutividade elétrica e cloretos como indicador da qualidade de água

“…As águas doces superficiais são amplamente exploradas por serem facilmente acessíveis, o que causa severos distúrbios na qualidade e escassez deste recurso. Dentre as várias causas de poluição dos corpos hídricos tem-se, principalmente, o uso e ocupação do solo, acidentes ambientais, desmatamento, escoamento agrícola, descarte de resíduos, de efluentes domésticos e industriais (PASSOS et al, 2019;TRIPATHI e SINGAL, 2019).…”