The effects of oscillation period on groundwater wave dispersion in a sandy unconfined aquifer: Sand flume experiments and modelling

JOURNAL OF HYDROLOGY

卷:533

Article

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

[1] Griffith Univ, Griffith Sch Engn, Gold Coast Campus, Southport, Qld 4222, Australia

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

[3] Ctr Hydrogeol, Rue Emile Argand 11,Case Postale 158, CH-2009 Neuchatel, Switzerland

关键词: Groundwater wave;    Hysteresis;    Unsaturated flow;    Seepage face;    Richards' equation;   

DOI  :  10.1016/j.jhydrol.2015.12.032

来源: Elsevier

【 摘 要 】

This paper presents a new laboratory sand flume dataset on the propagation of groundwater waves in an unconfined sandy aquifer with a vertical boundary subject to simple harmonic forcing with a wide range of oscillation period from 10.7 s to 909 s. The data is unique in that it covers a much wider range of non-dimensional aquifer depths, n omega d/K (where n is the porosity, omega is the angular frequency, d is the aquifer depth and K is the hydraulic conductivity) than has been previously investigated. Both the amplitude decay rate and rate of increase in phase lag of the water table waves are observed to monotonically increase with increasing oscillation frequency (increasing n omega d/K). This is in contrast to existing theoretical dispersion relations which predict: (1) zero phase lag or standing wave behaviour and (2) an asymptotic decay rate as the frequency increases. Possible influences on the experimental data including sand packing, measurement location, finite amplitude wave effects, unsaturated zone truncation and multiple wave mode effects are unable to explain the discrepancy. The data was also compared against numerical solutions of Richards' equation with and without hysteresis and in both cases, the same qualitative behaviour as the analytic solutions described above is found. The discrepancy between data and predictions remains unexplained and highlights a knowledge gap that requires further investigation. These findings relate directly to practical applications in the field of surface-groundwater interactions such as the influence of wave forcing of coastal aquifers on contaminant transport, sediment mobility and salt-water intrusion all of which are influenced by the dispersion of the groundwater wave. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.

【 授权许可】

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