Periodic seepage face formation and water pressure distribution along a vertical boundary of an aquifer

JOURNAL OF HYDROLOGY

卷:523

Article

Shoushtari, Seyed Mohammad Hossein Jazayeri¹  Nielsen, Peter²  Cartwright, Nick¹  Perrochet, Pierre³ 

[1] Griffith Univ, Griffith Sch Engn, Brisbane, Qld 4222, Australia

[2] Univ Queensland, Sch Civil Engn, Brisbane, Qld 4072, Australia

[3] Ctr Hydrogeol, CH-2009 Neuchatel, Switzerland

关键词: Groundwater;    Seepage face;    Capillary fringe;    Richards' equation;   

DOI  :  10.1016/j.jhydrol.2015.01.027

来源: Elsevier

【 摘 要 】

Detailed measurements of the piezometric head from sand flume experiments of an idealised coastal aquifer forced by a simple harmonic boundary condition across a vertical boundary are presented. The measurements focus on the pore pressures very close to the interface (x = 0.01 m) and throw light on the details of the boundary condition, particularly with respect to meniscus suction and seepage face formation during the falling tide. Between the low and the mean water level, the response is consistent with meniscus suction free models in terms of both the vertical mean head and oscillation amplitude profiles and is consistent with the observation that this area of the interface was generally within the seepage face. Above the mean water level, the influence of meniscus formation is significant with the mean pressure head being less than that predicted by capillary free theory and oscillation amplitudes decaying faster than predicted by suction free models. The reduced hydraulic conductivity in this area due to partial drainage of pores on the falling tide also causes a delay in the response to the rising tide. The combined influence of seepage face formation, meniscus suction and reduced hydraulic conductivity generate higher harmonics with amplitudes of up to 26% of the local main harmonic. To model the influence of seepage face formation and meniscus suction a numerical solution of the Richards' equation was developed and evaluated against the data. The model-data comparison shows a good agreement with the behaviour high above the water table sensitive to the choice of moisture retention parameters. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.

【 授权许可】

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