Salt Groundwater Intrusion in the Pleistocene Aquifer  in the Southern Part of the Red River Delta, Vietnam

Hoan, Hoang Van; Larsen, Flemming; Lam, Nguyen Van; Nhan, Dang Duc; Luu, Tran Thi; Nhân, Phạm Quý

doi:10.25073/2588-1094/vnuees.4127

Cited by 4 publications

(4 citation statements)

References 17 publications

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“…The compositions of squeezed pore water from cores are shown in Table 3. A peak with a pore water chloride concentration of 15,286 mg/L at 16.30 mbsl corresponds to the salinity of approximately 80 % of seawater (Hoang et al, 2018). The EC of this water sample is 5,080 mS/m, and the calculated pore water resistivity is 0.2 Ω m. The data confirms the low formation resistivities below 1 Ω m in the TEM soundings at these depths in the formation (Fig.…”

Section: Exploratory Boreholessupporting

confidence: 76%

Recharge mechanism and salinization processes in coastal aquifers in Nam Dinh province, Vietnam

Van¹,

Larsen

Quy

et al. 2022

Vietnam J. Earth Sci.

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In Nam Dinh province, in the Red River delta plain in Northern Vietnam, groundwater in the shallow Holocene aquifer shows elevated total dissolved solids up to 35 km from the coastline, indicating a saltwater intrusion from the Gulf of Tonkin. High groundwater salinities have been encountered below and adjacent to the Red River in the deep Pleistocene aquifer. Since 1996, large-scale groundwater abstraction was initiated from the deep aquifer, and the observed elevated salinities now raise concerns about whether the groundwater abstraction is undertaken sustainably. We have conducted a study to obtain a fundamental understanding of the recharge mechanisms and salinization processes in the Nam Dinh province. A holistic approach with multiple methods including transient electromagnetic sounding and borehole logging, exploratory drilling, sampling and analyzing primary ion and stable isotope compositions of water and pore water, groundwater head monitoring, hydraulic experiments laboratory of clay layers, and groundwater modeling by using the SEAWAT code. Results reveal that saline river water is leached from the Red River and its distributaries into the shallow aquifers. The distribution and occurrence of salty pore water in the Holocene aquitard clay shows that meteoric water has not been flowing through these low permeable clay layers. Marine pore water has, however, been leached out of the Pleistocene clay. When this layer is present, it offers protection of the lower aquifer against high salinity water from above. Salinity as high as 80 % of oceanic water is observed in interstitial pore water of the transgressive Holocene clay. Saltwater is transported into the Pleistocene aquifer, where the Holocene clay is directly overlying the aquifer.

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Section: Exploratory Boreholessupporting

confidence: 76%

Recharge mechanism and salinization processes in coastal aquifers in Nam Dinh province, Vietnam

Van¹,

Larsen

Quy

et al. 2022

Vietnam J. Earth Sci.

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“…In the past, groundwater flow and salinization models have been developed for Vietnam (H. Van Hoan et al, 2018;Jusseret et al, 2009;Lam et al, 2021), as well as for the Mekong Delta (MKD), in particular (Gunnink et al, 2021;Hung et al, 2019;Minderhoud et al, 2020;Nam et al, 2019;Vuong et al, 2014). Modeling approaches have primarily employed the MODFLOW software package and have mostly covered large areas.…”

Section: Introductionmentioning

confidence: 99%

The Process of Groundwater Salinization on the Ca Mau Peninsula (Mekong Delta, Vietnam): Evaluation of Saltwater Intrusion Pathways via Scenario Calculations Applying a 3D Groundwater Model

Hoan,

Richter,

Doerr

et al. 2023

Preprint

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Ca Mau Peninsula (CMP), the southernmost region of the Mekong Delta, is facing a severe loss of land and freshwater. Particularly, the groundwater resources in the complex multilayered aquifer system of CMP are subject to salinization processes, which are not yet fully understood. In this study, an existing groundwater flow model for the CMP was enhanced to a density-dependent transient transport model using the FEFLOW software package, which is based on the finite element method. The study focuses on simulating groundwater salinity in order to better understand the dynamics of groundwater salinization and potential saltwater intrusion pathways in the study area. Time series of Total Dissolved Solids (TDS) concentrations at observation wells were used to compare simulated and observed salinity data in different aquifers. The model allows a multi-factorial evaluation of the spatial groundwater salinity and could also confirm significant inter-annual variability, particularly in the case of shallow aquifers due to the influence of tides and seasonal rainy/dry seasons. Using sensitivity analysis, leakage from upper saline aquifers into lower freshwater aquifers through natural hydrogeological windows and poorly sealed boreholes was identified as a potential major cause for groundwater salinization occurring in the region. The results obtained can serve as an important basis for developing decision-making tools to promote the sustainable use of water resources on the CMP in the future.

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“…Saltwater origin and mechanisms in coastal aquifers in Vietnam have been studied extensively and the main causes identified are groundwater exploitation [9]; inter-aquifer leakage due to diffusion and density flow or high hydraulic gradient [10].…”

Section: Introductionmentioning

confidence: 99%

Zrozumienie mechanizmów pochodzenia słonej wody w przybrzeżnych warstwach wodonośnych obszaru Da Nang (środkowy Wietnam)

NGUYEN,

DUC,

DAO

2023

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Przedostanie się słonej wody do szybko rozwijającego się miasta Da Nang w Wietnamie powoduje obecnie różne wyzwania związane z gospodarką wodną, w tym niedostateczne zaopatrzenie w wodę i jej zanieczyszczenie. Do zbadania pochodzenia i mechanizmu powstawania słonej wody w holoceńskich i plejstoceńskich warstwach wodonośnych wykorzystano zintegrowany model numeryczny SWAT-MODFLOW. Do walidacji wykorzystano metody geofizyczne i izotopowe model SEAWAT zastosowany do symulacji intruzji słonej wody. Wyniki sugerują, że przypływy i odpływy, a także poziom wody w rzekach wpływają przede wszystkim na przybrzeżne warstwy wodonośne. Jednakże skuteczne planowanie i zarządzanie zasobami wodnymi, wraz z utrzymaniem naturalnego uzupełniania słodkiej wody z lokalnych opadów w porze deszczowej, mogłoby umożliwić racjonalne i efektywne wykorzystanie wód gruntowych, ograniczając przedostawanie się słonej wody na wiele obszarów. W porze suchej woda gruntowa jest uzupełniana z obszarów położonych wyżej. Obecna intruzja słonej wody występuje głównie wzdłuż rzek aż do tamy hydraulicznej. Modele symulacyjne, wykorzystujące scenariusze zaprzestania poboru wód podziemnych, ale przejścia na wykorzystanie wód powierzchniowych do celów pitnych, pokazują, że po 30 latach powierzchnia wód zasolonych szybko się kurczy, zmniejszając się z 59,6 km2 do 39,5 km2 i z 40,2 km2 do 28,6 km2 w odpowiednio w warstwach holocenu i plejstocenu.

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Salt Groundwater Intrusion in the Pleistocene Aquifer in the Southern Part of the Red River Delta, Vietnam

Cited by 4 publications

References 17 publications

Recharge mechanism and salinization processes in coastal aquifers in Nam Dinh province, Vietnam

Recharge mechanism and salinization processes in coastal aquifers in Nam Dinh province, Vietnam

The Process of Groundwater Salinization on the Ca Mau Peninsula (Mekong Delta, Vietnam): Evaluation of Saltwater Intrusion Pathways via Scenario Calculations Applying a 3D Groundwater Model

Zrozumienie mechanizmów pochodzenia słonej wody w przybrzeżnych warstwach wodonośnych obszaru Da Nang (środkowy Wietnam)

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