Development of river water quality indices—a review

Abstract

The use of water quality indices (WQIs) as a tool to evaluate the status of water quality in rivers has been introduced since the 1960s. The WQI transforms selected water quality parameters into a dimensionless number so that changes in river water quality at any particular location and time could be presented in a simple and easily understandable manner. Although many WQIs have been developed, there is no worldwide accepted method for implementing the steps used for developing a WQI. Thus, there is a continuing interest to develop accurate WQIs that suit a local or regional area. This paper aims to provide significant contribution to the development of future river WQIs through a review of 30 existing WQIs based on the four steps needed to develop a WQI. These steps are the selection of parameters, the generation of sub-indices, the generation of parameter weights and the aggregation process to compute the final index value. From the 30 reviewed WQIs, 7 were identified as most important based on their wider use and they were discussed in detail. It was observed that a major factor that influences wider use of a WQI is the support provided by the government and authorities to implement a WQI as the main tool to evaluate the status of rivers. Since there is a lot of subjectivity and uncertainty involved in the steps for developing and applying a WQI, it is recommended that the opinion of local water quality experts is taken, especially in the first three steps (through techniques like Delphi method). It was also observed that uncertainty and sensitivity analysis was rarely undertaken to reduce uncertainty and hence such an analysis is recommended for future studies.

Evaluation of Groundwater Quality Using CCME Water Quality Index in the Rooppur Nuclear Power Plant Area, Ishwardi, Pabna, Bangladesh

“…The first systematic WQI attempt for Categorization of water quality started in the mid-twentieth century by Horton in 1965 [10]. Then in 1970 Brown et al developed a general Water quality index [26]. In 1982 Steinhart et al applied a novel environmental quality index to sum up technical information on the status and trends in Great Lakes ecosystem.…”

“…Water Quality Guidelines Task Group of the Canadian Council of Ministers of the Environment introduced WQI in Canada, in the mid-1990s [8,29]. Some frequently used WQI in public domains are the US National Sanitation Foundation Water Quality Index, NSFWQI, Florida Stream Water Quality Index, FWQI, British Columbia Water Quality Index, BCWQI, Oregon Water Quality Index, OWQI and the Canadian Water Quality Index Canadian Council of Ministers of the Environment [26]. The original BCWQI was modified into the CCME WQI, which was certified by the Canadian Council of Ministers of the Environment [14].…”

“…A water quality index (WQI) is a single dimensionless number expressing the water quality in a simple form by aggregating the measurements of selected parameters [26,49]. WQI can be estimated on the basis of various physicochemical parameters.…”

“…Therefore, for such situations only few critical parameters must be used to evaluate WQI [28]. In the present study, the Canadian Council of Ministers of the EnvironmentWater Quality Index 1.0 (CCME WQI) was used, which is a well-accepted and universally applicable computer model for evaluating the water quality index (Canadian Council of Ministers of the Environment [7,26,28,44,46]. It can combine a variety of different measurement units in a single metric and is effective as a communication tool.…”

Assessment of Quality of Groundwater in Certain Villages nearby Krishna River, Krishna District, Andhra Pradesh, India

“…Using WQI, it is possible to indicate quality of water in a simple form by the aggregation of the measurements of the selected parameters. Considering the easiness of the use of WQI and their scientific basis, WQIs became important and popular tool for the assessment of water quality of water bodies [3]. WQI attempts to provide a mechanism for presenting a cumulatively derived numerical expression defining a certain level of water quality [4].…”