Spatio-temporal analysis of water quality of urban river network based on WQI and multivariate statistics

As one of the most important river basins in China, the Haihe River is confronted with significant water quality challenges, which indicates the need for effective methods to assess the water quality. This study evaluates the water quality of the southern Haihe River network in 2020 using data from 18 monitoring sites across 9 rivers. Water Quality Index (WQI), cluster analysis, and principal component analysis (PCA) were employed to assess spatial and temporal pollution patterns. WQI values ranged from 60 to 90, indicating moderate to good water quality. Organic matter, nitrogen, and phosphorus were identified as key pollutants, with seasonal fluctuations influenced by water supplement. Spatial clustering highlighted areas with poor water circulation and high non-point source pollution. PCA supported these findings, revealing consistent pollutant profiles across time and space. The results underscore the spatiotemporal variability of water quality and provide valuable guidance for water management in urban river ecosystems.