Seasonal and tidal influence on surface water quality in Hau river, Hau Giang province

Abstract

The study aimed to evaluate the influence of seasons and tides on the surface water quality of the Hau river in Hau Giang province, Vietnam. Water quality data were collected at six locations at low tide and high tide. The monitoring parameters included pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), ammonium (NH₄⁺-N), nitrate (NO₃^--N), orthophosphate (PO₄^3--P), total phosphorus (TP), total nitrogen (TN), iron (Fe), and coliform. One-way analysis of variance (One-way ANOVA), cluster analysis (CA), and discriminant analysis (DA) were applied to determine the influence of tides and seasons on water quality. Surface water quality is compared with the national technical regulation on surface water quality. It showed that surface water in the study area had organic pollution and high eutrophication potential. The parameters of BOD, COD, TN, TP, Fe, PO₄^3--P and coliform in low tide tended to be higher than those in high tide. Five parameters including TSS, TP, TN, PO₄^3--P and coliform had a significant difference between the wet season and the dry season by DA analysis. Cluster analysis classified water quality into three clusters mainly by parameters BOD, COD, TSS, PO₄^3--P and Fe. The study provides important information on the water quality of the Hau river in Hau Giang province for water use and monitoring.