Tidal effects on groundwater dynamics in unconfined aquifers

Ataie-Ashtiani, B., Volker, R. E. and Lockington, D. A. (2001) Tidal effects on groundwater dynamics in unconfined aquifers. Hydrological Processes, 15 4: 655-669. doi:10.1002/hyp.183

Author Ataie-Ashtiani, B.
Volker, R. E.
Lockington, D. A.
Title Tidal effects on groundwater dynamics in unconfined aquifers
Journal name Hydrological Processes   Check publisher's open access policy
ISSN 1099-1085
Publication date 2001-03
Sub-type Article (original research)
DOI 10.1002/hyp.183
Volume 15
Issue 4
Start page 655
End page 669
Total pages 15
Place of publication West Sussex, England
Publisher John Wiley & Sons Ltd
Language eng
Subject 0905 Civil Engineering
Abstract The variation of seawater level resulting from tidal fluctuations is usually neglected in regional groundwater flow studies. Although the tidal oscillation is damped near the shoreline, there is a quasi-steady-state rise in the mean water-table position, which may have an influence on regional groundwater flow. In this paper the effects of tidal fluctuations on groundwater hydraulics are investigated using a variably saturated numerical model that includes the effects of a realistic mild beach slope, seepage face and the unsaturated zone. In particular the impact of these factors on the velocity field in the aquifer is assessed. Simulations show that the tidal fluctuation has substantial consequences for the local velocity field in the vicinity of the exit face, which affects the nearshore migration of contaminant in coastal aquifers. An overheight in the water table as a result of the tidal fluctuation is observed and this has a significant effect on groundwater discharge to the sea when the landward boundary condition is a constant water level. The effect of beach slope is very significant and simplifying the problem by considering a vertical beach face causes serious errors in predicting the water-table position and the groundwater flux. For media with a high effective capillary fringe, the moisture retained above the water table is important in determining the effects of the tidal fluctuations. Copyright © 2001 John Wiley & Sons, Ltd.
Keyword Coastal aquifer
Groundwater flow
Numerical model
Seepage face
Tidal fluctuation
Variably saturated flow
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Civil Engineering Publications
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Created: Tue, 11 Apr 2006, 01:44:43 EST