Using Entropy weight for determining the Entropy Water Quality Index (EWQI) of a water-scarce region in Long An province

Abstract

The Water Quality Index (WQI) is essential for assessing water quality worldwide. In Vietnam, the methodology for calculating and issuing the WQI is specified in document No. 1460/QD-TCMT. However, the weight assigned to each parameter in the WQI calculation often depends on subjective judgment or pre-determined regulations, potentially introducing bias and uncertainty into the results. This study seeks to improve the objectivity of water quality assessments by incorporating Entropy weights into the evaluation process, leading to the development of an Entropy Water Quality Index (EWQI). Applied in a water-scarce region in Long An province, the EWQI yielded more reliable results. The findings show that the surface water quality was significantly good, while the groundwater quality was generally excellent across most sampling points.