Salt groundwater intrusion in the Pleistocene aquifer in the southern part of the Red River Delta, Vietnam

Van Hoan Hoang, Flemming Larsen, Van Lam Nguyen, Duc Nhan Dang, Thi Luu Tran, Quy Nhan Pham

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Fresh groundwater was found in the Pleistocene aquifer in the southern part of the Red River Delta in 70’s of last century. It is located mainly in the south of Nam Dinh province and small part in southeast of Ninh Binh province. The fresh-saline boundary seems to migrate southward recently and downsize the area of fresh groundwater. It is necessary to find out the mechanisms of salt intrusion into the zone of freshwater in order to mitigate the negative impacts to the quality of water supply. Based on the survey data of groundwater chemistry, transient electromagnetic sounding, borehole logging, drilling, and chemical analysis of pore water squeezed from the low permeable sediment in the study region, it was determined the current spatial distribution of saline water in the Pleistocene aquifer and in marine clay layers. By combining these data with the results from previous studies, this study has determined the mechanisms of the salt intrusion into the freshwater zone. It was found that salinity in the Pleistocene aquifer is generated from two main sources (1) Vertical salt intrusion from the upper marine clay layer which is controlled by the diffusion and density flow and (2) Horizontal saltwater incursion due to the high hydraulic gradient which is controlled by the convection and dispersion which was generated by over groundwater exploitation.
Original languageEnglish
Pages (from-to)11-22
Number of pages12
JournalVNU Journal of Science: Earth and Environmental Sciences
Volume34
Issue number1
Publication statusPublished - 2018

Programme Area

  • Programme Area 2: Water Resources

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