Spatiotemporal assessment and pollution-source identification and quantification of the surface water system in a coastal region of Vietnam

ABSTRACT Surface water quality in coastal regions may be degraded due to various pollution sources, including seawater intrusion, dependent on season and distance from the coastline. This study aimed to fractionate and quantify pollution sources affecting surface water quality in a coastal region of Vietnam. Between 2016 and 2020, 400 surface water samples were collected from 40 sites during dry and rainy seasons and analysed for 15 parameters. The results showed that four primary pollution sources – seawater intrusion, agricultural production, residential activities, and human activities impacting the hydrological system – may contribute to the degradation of water quality. Seawater intrusion contributed approximately 83.3% to the determination of water quality in dry seasons and 35.3% in rainy seasons. Water quality was more degraded in areas within 20 km of the coastline than in more distant areas. A management strategy should be developed and implemented to improve surface water quality for sustainable development.