The first step of application of water quality index (WQI) to assessment of sea water quality in the Gulf of Tonkin in 2018

Abstract

The study to calculate the water quality index was conducted in the Gulf of Tonkin at the surface water in August 2018. The calculation results showed that out of 48 surveyed points, there was 1 point in the Northeast area at poor water quality, 15 points in the Northeast and coastal areas from Thanh Hoa to Thua Thien Hue at medium water quality, 14 points in the Gulf of Tonkin, Northeast and Con Co Island at good water quality, the remaining 18 points in the Gulf of Tonkin and Bach Long Vi Island at excellent water quality. Overall, the average water quality of the whole region was good (average WQI = 79). Considering each area, the Gulf of Tonkin area had good and excellent water quality, the Northeast had water quality from poor to good level, the coastal areas from Thanh Hoa to Thua Thien Hue had medium water quality, Con Co Island area had good water quality, Bach Long Vi Island area had excellent water quality.