Estimation of seawater retreat timescales in homogeneous and confined coastal aquifers based on dimensional analysis

ABSTRACT

Reliable estimation of the timescales of seawater retreat (SWR) in coastal aquifers has significant implications for sustainable groundwater management in coastal areas. Due to the complexity of coastal dynamics, analytical estimates of SWR timescales are limited in number, and numerical models are mainly utilized. Although numerical models allow for accurate analysis of the coastal systems, they concern particular aquifer cases, thus their results are not generally applicable. Here, we perform a dimensional analysis for the depth-integrated freshwater/seawater continuity equations and identify the dimensionless parameters that affect SWR in confined, homogeneous and flux-controlled aquifers. Based on numerical simulations, we gain insight into how these parameters affect SWR, and produce type curves which can be used as a simple tool for estimating SWR timescales in idealized coastal systems, independent of the hydraulic and geometric characteristics of the aquifer. The reliability of our estimates in real-world applications is also discussed.

KEYWORDS:

• seawater retreat timescales
• dimensional analysis
• coastal aquifers
• sharp interface approach
• Ghyben-Herzberg approximation
• groundwater dynamics
• heterogeneity

Editor R. Woods; Associate editor A. Fiori

Editor R. Woods; Associate editor A. Fiori

Acknowledgements

The authors would like to thank the associate editor Professor Aldo Fiori and two anonymous reviewers for their helpful comments and suggestions that greatly improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work of Antonios Mamalakis was supported by LIFE (Linked Institutions for Future Earth) funded under NSF’s Science Across Virtual Institutes (SAVI) programme (NSF grant EAR-1242458).