Towards a correlation between long-term seawater intrusion response and water level fluctuations

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
23 Downloads (Pure)

Abstract

Laboratory and numerical experiments were conducted to provide a quantitative steadystate analysis of the effect of incremental variations of water level on saltwater intrusion. The purpose was to seek mathematical correlations relating both the wedge toe length and the height along the coastline to the boundary head difference. The laboratory experiments were completed in a 2D sand tank where both freshwater and seawater levels were varied. The experiments were conducted for two bead sizes having different hydraulic conductivities. The numerical model SEAWAT was used to validate the results and then to perform sensitivity analysis. The experimental results show that at steady-state conditions, the logarithmic toe length could be expressed as a linear function of the boundary head difference. The linear relationship was recorded in both advancing and receding wedge phases. The linearity of the correlation was also well demonstrated with analytical solutions. Similar relationships were also derived in the scenarios where the sea level fluctuated while the freshwater boundary head was constant. The height of the saltwater wedge along the coastline was also found to be a linear function of the boundary head difference. The sensitivity analysis shows that the regression coefficients were sensitive to the hydraulic conductivity, the dispersivity, and the saltwater density, while the porosity and the rate of boundary head change induced negligible effects. The existence of a linear relationship between the logarithmic toe length and the boundary head difference was also well evidenced in a field-scale aquifer model for all the different hydrogeological aquifer conditions tested. This study is the first attempt in identifying the underlying correlation between the boundary water level variations and the main seawater intrusion (SWI) external metrics under controlled laboratory conditions, which is of great relevance from a water resources management perspective.

Original languageEnglish
Article number719
Number of pages18
JournalWater
Volume13
Issue number5
Early online date06 Mar 2021
DOIs
Publication statusPublished - 06 Mar 2021

Bibliographical note

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • Density-driven flow
  • Saltwater intrusion predictions
  • Sea level rise
  • SEAWAT
  • Transient seawater intrusion

ASJC Scopus subject areas

  • Biochemistry
  • Geography, Planning and Development
  • Aquatic Science
  • Water Science and Technology

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