Major concerns of surface water quality in south-west coastal regions of Vietnamese Mekong Delta

Abstract This study aimed to appraise seasonal variations in surface water quality on the coasts of Southwestern Vietnam using entropy-weighted index (EWQI) and multivariate statistics: cluster analysis (CA), principal component (PCA), discriminant (DA). Forty-nine samples monitored Kien Giang province during rainy dry seasons were analysed for 16 physiochemical biological parameters. Compared Vietnamese standard, areas was contaminated with organic matter (high oxygen demand chemical demand), nutrients ammonium (NH 4 + ), nitrite, orthophosphate), total suspended solids (TSS), iron (Fe), coliform. Seasonal coastal regions observed. TSS, microbial problems bodies tend be more serious due an increase flow containing pollutants from upstream wastes regional human activities. Meanwhile, salinity season (0–32‰) greatly higher, which caused only 10% suitable irrigation. CA extracted 11 13 clusters 49 locations seasons, respectively. Five components obtained PCA can explain 74 70% Moreover, results suggested that natural factors (hydrological regimes, temperature, rainfall, sea-level rise) sources (domestic, agriculture, industry, tourism) are accountable these fluctuations. DA 7 parameters (pH, salinity, Fe, nitrate, NH , chloride) leading difference quality, 88% correct assignation. EWQI revealed about 66% classified as a very bad drinking season. However, this ratio declined 59% Although slightly improved season, pollution need concerned. The findings provide insights into application statistics EWQI, could support policymakers developing management strategies.