Assessment of spatial-temporal variations in surface water quality of Luzhi river system in Plain River-Net Areas, Suzhou, China

Understanding the spatial-temporal distributions and variations of water quality index are important for pollution sources identification and are essential for efficient water environment management. Reasonable designed monitoring networks of rivers and the periodical monitoring campaign can provide the water quality data to describe the spatial-temporal vision of the river water quality state. Multiple statistical methods are reliable and effective in interpreting the monitoring water quality data set. In this study, multiple statistical methods including cluster analysis (CA) and factor analysis (FA) were used to evaluate the temporal-spatial variations of water quality of Luzhi river system in Plain River-Net Areas, Suzhou, China. The results showed that: (1) water quality of Luzhi river system exists obvious temporal-spatial distribution characteristic, The sampling periods were categorized into two groups corresponding to seasonal changes in water quality, Sampling sites were classified into three groups which represented different water quality levels and pollution degrees. (2) Three factors were extracted by using FA method and they reflected nitrogen and phosphorus levels of the water, organic and physical conditions respectively. (3) The varifactors obtained from FA indicate that the parameters responsible for water quality variations of different monitoring site are mainly related to corresponding geographical location pollution source situation and the hydrodynamic characteristics. The study provided critical information for water quality management in the Luzhi river-net areas.