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WRRCTR No.51 The Response to Tidal Fluctuations of Two Non-Homogenous Coastal Aquifer Models

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Title: WRRCTR No.51 The Response to Tidal Fluctuations of Two Non-Homogenous Coastal Aquifer Models
Authors: Williams, John A.
Liu, Ta-Chiang
LC Subject Headings: Aquifers -- Electromechanical analogies.
Aquifers -- Mathematical models.
Groundwater flow -- Mathematical models.
Groundwater flow -- Electromechanical analogies.
Tides -- Mathematical models.
Issue Date: Nov 1971
Publisher: Water Resources Research Center, University of Hawaii at Manoa
Citation: Williams JA, Liu TC. 1971. The response to tidal fluctuations of two non-homogenous coastal aquifer models. Honolulu (HI): Water Resources Research Center, University of Hawaii at Manoa. WRRC technical report, 51.
Series/Report no.: WRRC Technical Reports
Abstract: Mathematical and electric analog (R-C circuit) models for two one-dimensional non-homogeneous coastal aquifers have been developed. The first is a semi-infinite aquifer having a discontinuous change in permeability at a distance L from the coastline and the second is an aquifer of length L whose permeability changes linearly with distance from the coastline and whose interior boundary represents either a constant head op a no-flow condition. Both models were subjected to a sinusoidal tidal input. Results, in the form of graphs of amplitude and phase angle vs. position, show excellent agreement between the outputs of the mathematical and electric analog models. In the case of a discontinuous permeability, these graphs indicate a positive or negative reflection from the discontinuity for a decrease or increase, respectively, in the permeability. In the case of the linearly varying permeability model, the graphs of amplitude indicate that energy is attenuated at a greater rate near the coastline than K[sub]L/K[sub]O <1 for both types of boundary condition. Graphs of the phase angle are concave downwards for the constant-head boundary condition but for the no-flow condition they exhibit a point of inflection whose position depends on t[sub]o and K[sub]L/K[sub]O. Electric analog model results show that for the semi-infinite aquifer no significant error will result from the circuit configuration if a ≤ λ/50 and the circuit length is equivalent to 2λ, furthermore, "lumped" components, i.e., a = λ/5, may be used to extend the circuit beyond x = -0.4λ if measurements are restricted to x ≥ -0.2λ.
Sponsor: Supported in part by funds provided by the United States Department of the Interior as authorized under the Water Resources Act of 1964, Public Law 88-379. OWRR PROJECT NO. A-020-HI, GRANT AGREEMENT NO. 14-31-0001-3211
Pages/Duration: viii + 70 pages
Appears in Collections:WRRC Technical Reports

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