Relative water quality index (ReWQI) – a new method for aggregate water quality assessment
Ho Ngoc Pham
Abstract
Abstract Water quality index (WQI) is used for aggregate assessment of water pollution level. The method is used in the United States of America (USA) and some other countries including Vietnam, but it has several limitations: the weight of a parameter is subjectively defined by the experts' criteria; the hierarchical rating scale is self‐regulated and fixed; the individual index of WQI is calculated based on the segmented linear function, which are not convenient to apply in reality when expanding to an arbitrary number of selected survey parameters. In addition, in some cases, WQI results in ambiguity and eclipse (collectively called ‘Virtual effect’). To overcome these disadvantages, the author proposes Relative Water Quality Index (ReWQI). ReWQI's calculation is simple and it does not encounter ‘Virtual effect’. Results of ReWQI have been compared with results of the traditional method used by Department of Natural Resources and Environment of Hai Duong in 2016–2018.