Spatio-Temporal Assessment of Surface Water Quality in Tra Vinh Province, Vietnam, using Integrated Water Quality Indices and Cluster Analysis

IJEP 46(5): 417-423 : Vol. 46 Issue. 5 (May 2026)

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Nguyen Thanh Giao1*, Nguyen Minh Tam1,2, Tran Thi Kim Hong1, Ha Thao Nguyen1 and Nguyen Thi Cam Dien1

1. Can Tho University, College of Environment and Natural Resources, Can Tho, Vietnam
2. Department of Agriculture and Environment, Tra Vinh Province, Vietnam

Abstract

This study analyzed spatio-temporal variations in surface water quality across the watersheds of Tra Vinh province. The assessment used the organic pollution index (OPI), comprehensive pollution index (CPI), water quality index (WQI) and cluster analysis (CA). Water quality was evaluated using 12 physico-chemical parameters: pH, DO, TSS, COD, BOD5, N–NH4+, Cl-, P–PO43-, N–NO2-, N–NO3-, oil and grease and coliform. Results showed that OPI values, ranging from 0.88-23.82, classified water quality from good to heavily polluted. CPI values, from 0.48-5.12, indicated water quality ranging from slightly to heavily polluted. WQI scores, varying between 32-86, categorized water quality from poor to good. Furthermore, temporal cluster analysis of the six sampling months revealed that OPI values consistently indicated heavy pollution, CPI values ranged from moderate to heavy pollution and WQI scores classified water quality from moderate to poor. Spatial clustering showed significant differences among clusters. Conversely, temporal clustering suggested similar pollution characteristics across periods. Overall, water quality during the dry season months is not recommended for use. This research provides valuable information for the assessment and monitoring of water quality in Tra Vinh province.

Keywords

Water quality, Geographic information system, Organic pollution index, Comprehensive pollution index, Water quality index, Cluster analysis, Tra Vinh province, Mekong Delta

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