Analysis of Spatial-Temporal Variations of Surface Water Quality in the Southern Province of Vietnamese Mekong Delta Using Multivariate Statistical Analysis

The study aimed to assess the variation in surface water quality in the Tien Giang province, Vietnam, and at the same time identify the main sources of water pollution. The surface water quality samples were collected at 34 locations (NM01-NM34) with 17 surface water quality indicators in March, June, September and November in canals and rivers in the Tien Giang province. Multivariate statistical analysis methods, including principal component analysis (PCA), cluster analysis (CA) and numerical discriminant analysis (DA), were used to analyze the variability and key indicators affecting the effect of multivariate statistical analysis. The analysis results show that the surface water quality in the study area is contaminated with organic (low DO, high BOD and COD) and nutrients (NH4+-N, NO2--N, PO43--P and TP), salinity (high Cl-). The PCA results showed that 14/17 surface water environmental parameters to be monitored are pH, temperature, TSS, BOD, COD, NH4+-N, NO2--N, PO43--P, TP, SO42-, Cl-, coliform and Fe. The PCA analysis showed that PC1-PC4 accounted for 79.70% of the variation in surface water quality in the study area. Potential surface water polluting sources include hydrological regime, domestic waste, agricultural production, industrial production activities. The CA results showed that 34 monitoring locations can be reduced to 27 locations, with a frequency of 4 times/year to ensure surface water quality representativeness. The DA indicated that the indicators of EC, SO42- and Cl- made the difference of the surface water quality between the wet and dry seasons. The current results provide important information on the current state of water quality for different uses and contribute to the improvement of the surface water quality monitoring system in the Tien Giang province.