Title
Paleo-hydrogeological reconstruction of the fresh-saline groundwater distribution in the Vietnamese Mekong Delta since the late Pleistocene
Author
hung Van, Pham
van Geer, F.C.
bui Tran, V.
Dubelaar, W.
oude Essink, G.H.P.
Publication year
2019
Abstract
Study region: Mekong Delta, Vietnam (MKD). Study focus: Present-day distribution of fresh-saline groundwater is highly heterogeneous in the MKD. Close to the coastline, fresh groundwater is found in aquifers up to 500 m below ground surface. To gain better insight into the fresh-saline groundwater evolution since the late Pleistocene, we simulated long-term groundwater flow and salt transport in a two-dimensional NW-SW cross-section over the MKD. To fully consider the regression and transgression phases of sea-level changes over the past 60 ka, variable-density groundwater flow and salt transport was simulated with SEAWAT to reproduce characteristics of the present-day distribution of fresh-saline groundwater and its age. We simulated nine scenarios to evaluate the most important factors controlling freshening and salinization processes of the MKD groundwater system. We compared the final model stage with present day observations of groundwater salinity and age. New hydrological insights for the region: The sedimentation and erosion processes, related to sea-level changes over the last 60 ka, were important drivers of the fresh-saline distribution in the present MKD. The two-dimensional model indicates that most fresh groundwater in the MKD was recharged 60–12 ka before present, when the sea-level was at its lowest and the top sedimentary layers had a relatively high permeability. Due to deposition of a clayey top layer during the Holocene, at present, groundwater recharge of the deeper MKD groundwater system is very limited. © 2019 The Author
Subject
Geosciences
Groundwater
Variable-density modeling
Fresh-saline groundwater distribution
Salt water intrusion
Paleo-hydrogeology
Mekong Delta, Vietnam
Geological Survey Netherlands
2015 Energy
To reference this document use:
http://resolver.tudelft.nl/uuid:9bdbe07a-4632-47a5-a1e1-eeb613b861e8
DOI
https://doi.org/10.1016/j.ejrh.2019.100594/
TNO identifier
866872
Publisher
Elsevier B.V.
ISSN
2214-5818
Source
Journal of Hydrology: Regional Studies, 23 (23)
Document type
article