Analysis and prediction of the dynamic change of water quality in the inflow rivers

Abstract

The Le'an River (Jiangxi Province) is polluted by multiple point sources; however, fluctuations in its water quality factors have not been analysed or predicted. This study investigated the Spatio-temporal variation of the river’s water quality. Nine monitoring points were analysed to reveal the past and predict future trends based on field measurements from 2012 to 2020. The autocorrelation coefficient and duration for each monitoring point was evaluated using a rescaled range analysis. Pearson coefficient was calculated to clarify the correlation among monitoring points. The results show that: (1) the water quality of the lower reaches of Le'an River was inferior to Class V quality from 2012 to 2015, but it greatly improved after that, and the entire basin was classified as Class II after 2018; (2) upstream and downstream monitoring sites showed significant correlation characteristics among themselves, and the excessive downstream pollution was attributed to point source pollution from industrial wastewater discharged in Leping City; and (3) the Hurst index of all monitoring points was > 0.5; future water quality characteristics are expected to present long-term memory and persistence. Our results are of significance for controlling the water quality of the Le'an river and nearby economic zones.