Impact of layered heterogeneity on transient saltwater upconing in coastal aquifers

Antoifi Abdoulhalik*, Abdelrahman M. Abdelgawad, Ashraf A. Ahmed

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

This research investigated the effect of layered heterogeneity on transient saltwater upconing in a laboratory-scale coastal aquifer. The experiments were conducted in a 2D-laboratory flow tank, and the response of the saltwater wedge to pumping was analysed in a heterogeneous aquifer system, where a low permeability layer was constructed in the middle of the aquifer. The SEAWAT code was used for validation and to perform additional simulations to explore the sensitivity of the critical pumping rate and the critical time to the main parameters characterising the low-permeability layer, which included its permeability, thickness and position. The experimental results showed that the presence of layered heterogeneity noticeably altered the shape and the intrusion length of the upconing wedge without inducing a change in the abstraction rate “triggering” saltwater upconing mechanism compared to the homogeneous case. The numerical results of the layered aquifer provided excellent agreement with the experimental data for both the transient toe length and the shape of the steady-state saltwater wedges. The sensitivity analysis revealed that the critical pumping rate and the critical time was found to decrease considerably with decreasing hydraulic conductivity and thickness of the middle layer, which evidences the higher vulnerability of such layered aquifer systems to the saltwater upconing, in comparison to idealised homogeneous systems. The results nonetheless showed that varying the position of the interlayer induced very little change on the critical pumping rate, but the critical time would tend to decrease as the low permeability layer was moved deeper away from the pumping well, particularly for smaller middle layer thickness.

Original languageEnglish
Article number124393
JournalJournal of Hydrology
Volume581
Early online date22 Nov 2019
DOIs
Publication statusEarly online date - 22 Nov 2019

Bibliographical note

Funding Information:
The experiments of this work were carried out at Queen's University Belfast when the first and third authors were associated with the institution.

Publisher Copyright:
© 2019 Elsevier B.V.

Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.

Keywords

  • Aquifer salinisation
  • Laboratory experiments
  • Numerical modelling
  • Saltwater upconing
  • SEAWAT
  • Seawater intrusion

ASJC Scopus subject areas

  • Water Science and Technology

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