An improved index for water quality evaluation in an estuary region: a case study in the Eastern Pearl River Delta, China

Abstract

Abstract Water quality evaluation is fundamental for water resources management. In this study, a water quality index (WQI) was constructed to evaluate water quality in an estuary region. First, principal component analysis and the Bartlett method were used to select more important water quality parameters from multivariables. Second, quality curves and weights of selected parameters were assigned, and then WQI scores were calculated. The WQI method was applied to the Eastern Pearl River Delta in China as a case study. Results showed that water quality in the upstream area and the coastal region was better than in the central delta, with an average WQI of 72, 55 and 14, respectively. Results further revealed that water quality in the coastal region was more variable (the standard variation of WQIs is near 20) due to more rapid changes in hydrologic features, while water quality in the inland area was more stable (the standard variation is around 10). Comparison between the WQI and fuzzy evaluation methods indicated the reliability of the WQI method. This WQI method can evaluate water quality in the estuarine delta area well, and statistical techniques used in this paper can be applied in different geographical areas considering their specific characteristics.