Development of Water Quality Indices (WQIs): A Review

Various physical, chemical and biological variables are considered detrimental to the aquatic environment, especially if contained in excessive amounts. Such parameters originate from anthropogenic and natural sources. Though some might be essential in the aquatic ecosystem, they might pose a serious risk if present in excessive concentrations. Eventually, monitoring and assessing water resources becomes mandatory in order to trace the levels and effects of such physio-chemical and biological parameters. And the common practical method is through the application of water quality indices (WQIs). This prompts the need to further exploit the use of WQIs and continuously modify such important tools in order to become better, simpler and more appropriate toward water resource management needs; which needs are dynamic and forever changing. The current study focuses on developing a universal water quality model for South African river catchments. And as part of the study, this review work attempts to outline the objectives of establishing water quality monitoring tools, their classification and the basic procedure of developing WQIs.