Assessment of water quality in Hawkesbury-Nepean River in Sydney using water quality index and multivariate analysis

Abstract

This study has assessed the water quality status of the Hawkesbury-Nepean River (HNR) in Sydney, Australia. It is based on the collected data of 12 water quality parameters at four monitoring stations along the river. HNR is one of the most important rivers in Australia which supplies over 90% of Sydney's potable water for more than 4.8 million people. Canadian Water Quality Index (CWQI) is adopted in this study to summarise the water quality status at the individual stations by categorising the water quality in five divisions; poor, marginal, fair, good and excellent. In addition, water quality parameters are regressed with the calculated CWQI to identify the significant parameters. Based on the calculated CWQI, only one station is found to fall in 'fair' category, two in 'marginal' and one in 'poor' water quality categories. No significant trend is observed in the CWQI for the stations during the period of data collection; however, one station shows slight trend of decreasing water quality. The preliminary results of the regression analysis demonstrate that not all the water quality parameters are significant in explaining the CWQI at the stations. The results of this study are expected to provide useful information for water quality management, and to form the basis for further investigation.