Study on the salt intrusion in some river water sources serving for domestic water supply in coastal areas of Vietnam

Abstract

Saline intrusion in Vietnam’s coastal areas has been significantly increased by climate change and anthropogenic activities, particularly water resource exploitation. This paper presents a comprehensive assessment of salinity levels within river systems supplying domestic water, with a focus on the Mekong Delta, Central Coast, and Northern regions. The findings indicate that saline intrusion fronts have penetrated inland distances ranging from tens to hundreds of kilometers. This penetration results in pronounced seasonal and diurnal (hourly) variations in river water salinity. Measured concentrations range from several hundred to tens of thousands of mg/L (quantified as Total Dissolved Solids, TDS), or up to several tens of parts per thousand (‰). River systems exhibiting high average salinity (> 1 ‰) include the Re, Cam, and Ninh Co rivers (North); the Yen, Cai, and Ma rivers (Central); and the Cua Tieu, Cua Dai, and Co Chien rivers (Mekong Delta). A critical associated issue is the elevated concentration of bromide ions (Br-) in saline-affected waters. This presence significantly increases the formation potential of carcinogenic disinfection byproducts (DBPs) during the chlorination process. Consequently, this study proposes technical solutions designed to mitigate and adapt to these adverse impacts on domestic water supplies