Use of index analysis to evaluate the water quality of a stream receiving industrial effluents

Abstract

In this paper, the water quality of a stream that receives industrial effluents is evaluated through the analysis of two indices. Data (dissolved oxygen, biochemical oxygen demand, pH, turbidity, colour, temperature and thermotolerant coliforms) were collected from five stations in the Mussuré Stream, located in João Pessoa (Northeast of Brazil), between January 1992 and December 2004. Spatial and temporary changes were recorded. The quality indices used, Objective Water Quality Index (WQI OBJ ) and Bascarón Adapted Water Quality Index (WQI BA ), presented similar trends and were considered adequate for evaluating the impacts of industrial effluent on water bodies. The flexibility of these indices relative to the parameters utilised in the calculations facilitates water quality evaluation in developing countries, where high cost and lack of necessary structure for analysis of other parameters are current deterrents to appropriate water quality evaluation.

Development of river water quality indices—a review

“…Such an aggregation method has been adopted and modified further in some WQIs (e.g. Pesce and Wunderlin 2000;Debels et al 2005;Abrahão et al 2007;Sánchez et al 2007;Koçer and Sevgili 2014).…”

Class frequency distribution for a surface raw water quality index in the Vaal Basin

“…In the end, an index should still provide a simple way of representing information by using a simple quality numerical value (Couillard and Lefebvre, 1985). Where costs and other challenges may limit water quality evaluation, selection of a streamlined list of the most appropriate quality parameters is, however, fundamental (Abrahão et al, 2007).…”

“…In addition, a model can predefine its input parameters or even the number of input parameters, both of which might not be available. Further, if a model requires a subjective constant that relates to a particular water body at a specific time of sampling, but which was not captured then, it renders the historical dataset inadequate for use with that model (Abrahão et al, 2007;Pesce and Wunderlin, 2000). Thus many indices have been developed since the first index was suggested by Horton (1965), to try to satisfy various conditions within ecological system boundaries, which constantly shift in time and space.…”

“…Further, even in catchments where data are aligned with specific sampling objectives, data for a required parameter, for example, might be unavailable, rendering the dataset inadequate for use with a specific water quality index (WQI). Yet indices are expected to provide simplified interpretation of results since in their various forms they summarise, in one value or concept, a series of parameters (Abrahão et al, 2007;Couillard and Lefebvre, 1985;DWAF, 1996). This is desirable, especially in cases where decisions require interpretation of the severity or extent of pollution impacts.…”

“…According to Abrahão et al (2007), these parameters should provide an indication of the evolutionary tendency of quality as it evolved over time, in addition to allowing for comparison between different watercourses or different locations along the same watercourse. Some indices use fixed numbers and specific input variables because they were objectively designed for comparison using some specific expert opinion.…”