Corrected interface flow model for seawater intrusion in confined aquifers: relations to the dimensionless parameters of variable-density flow

2018 ◽  
Vol 26 (8) ◽  
pp. 2547-2559 ◽  
Author(s):  
Antonis D. Koussis ◽  
Katerina Mazi
Keyword(s):  
Seawater Intrusion ◽  
Flow Model ◽  
Variable Density ◽  
Dimensionless Parameters ◽  
Variable Density Flow ◽  
Density Flow ◽  
Confined Aquifers

Prediction of seawater intrusion to coastal aquifers based on non-dimensional diagrams

2020 ◽  
Author(s):  
Charalampos Doulgeris ◽  
Evangelos Tziritis ◽  
Vassilios Pisinaras ◽  
Andreas Panagopoulos ◽  
Christoph Külls
Keyword(s):  
Hydraulic Conductivity ◽  
Case Studies ◽  
Seawater Intrusion ◽  
Coastal Aquifers ◽  
Variable Density ◽  
Real Case ◽  
Constant Thickness ◽  
Variable Density Flow ◽  
Density Flow ◽  
Dimensional Parameters

<p>A numerical analysis of the groundwater flow and contaminant transport equations, based on the variable density flow approach, is used for the construction of non-dimensional diagrams to predict seawater intrusion to confined coastal aquifers. The classical Henry’s seawater intrusion problem is analysed by using a finite element model. The model’s equations are written in non-dimensional form and the numerical solutions depend solely on three non-dimensional parameters:</p><p>α=q΄/Κ<sup>0</sup>, β=(bΚ<sup>0</sup>)/(nD<sub>m</sub>), α΄=bS<sup>0</sup>/n                                                                                           (eq. 1 a,b,c)</p><p>where q’ is the freshwater recharge rate (m/d), K<sup>0</sup> the freshwater hydraulic conductivity (m/d), b the aquifer thickness, n the porosity (-), D<sub>m</sub> the molecular diffusion coefficient (m<sup>2</sup>/d) and S<sup>0</sup> the freshwater specific storage (1/m). Please note that hydraulic conductivity appears in two of the non-dimensional parameters, α and β.</p><p>The non-dimensional formulation has led to the construction of non-dimensional diagrams of salt distribution for a homogeneous and isotropic confined aquifer with horizontal base and constant thickness that is uniformly recharged with freshwater. These diagrams illustrate the influence of the key hydrological and hydraulic parameters, and furthermore, can be used to predict the evolution of seawater intrusion in real case studies.</p><p>The numerical simulations were carried out up to the equilibrium state for different values of the non-dimensional parameters of equation 1. By decreasing the value of parameter α=q΄/Κ<sup>0</sup>, seawater intrusion is advancing inland and the width of dispersion zone is increasing. By increasing the parameter β=(bΚ<sup>0</sup>)/(nD<sub>m</sub>), the seawater-freshwater transition zone is narrowing and shifted to the seaside at the upper part of the aquifer, while the intrusion of saltwater is advancing inland at the lower part of the aquifer. The distribution of the salts in the aquifer was found essentially identical for different values of the parameter α΄=bS<sup>0</sup>/n; hence this parameter exhibits very low sensitivity, which makes it of low importance, especially for real case studies.</p><p>Overall, the non-dimensional diagrams – constructed by following the variable density flow approach and under specific assumptions – can be used for a quick and direct prediction of seawater intrusion in real aquifers. These diagrams would be useful for an initial prediction at the case studies of the PRIMA MEDSAL project (www.medsal.net), namely the coastal aquifers in Rhodope (Greece), Samos island (Greece), Bouficha (Tunisia), Bouteldja (Algeria), Tarsus (Turkey) and under specific assumptions to the karstic aquifer in Salento (Italy).</p>

scholarly journals Efficient Stochastic Simulation of Seawater Intrusion, With Mixing, in Confined Coastal Aquifers

2021 ◽  
Vol 3 ◽  
Author(s):  
Evangelos Rozos ◽  
Katerina Mazi ◽  
Antonis D. Koussis
Keyword(s):  
Seawater Intrusion ◽  
Coastal Aquifers ◽  
High Efficiency ◽  
Flow Region ◽  
Variable Density ◽  
Tracer Transport ◽  
Advection Dispersion ◽  
Variable Density Flow ◽  
Density Flow ◽  
Principal Directions

We present a high-efficiency method for simulating seawater intrusion (SWI), with mixing, in confined coastal aquifers based on uncoupled equations in the through-flow region of the aquifer. The flow field is calculated analytically and the tracer transport numerically, via spatial splitting along the principal directions (PD) of transport. Advection-dispersion processes along streamlines are simulated with the very efficient matched artificial dispersivity (MAD) method of Syriopoulou and Koussis and the system of discretized transverse-dispersion equations is solved with the Thomas algorithm. These concepts are embedded in the 2D-MADPD-SWI model, yielding comparable solutions to those of the uncoupled SWI equations with the state-of-the-art FEFLOW code, but faster, while 2D-MADPD-SWI achieves an at least hundredfold faster solution than a variable-density flow model. We demonstrate the utility of the 2D-MADPD-SWI model in stochastic Monte Carlo simulations by assessing the uncertainty on the advance of the 1,500 ppm TDS line (limit of tolerable salinity for irrigation) due to randomly variable hydraulic conductivity and freshwater flow rate.

Numerical Verification of the Solutions for Groundwater Flow in a Coastal Extensive Land Mass

2013 ◽  
Vol 864-867 ◽  
pp. 2292-2297
Author(s):  
Hai Peng Guo
Keyword(s):  
Analytical Solutions ◽  
Land Reclamation ◽  
Variable Density ◽  
Numerical Code ◽  
Numerical Verification ◽  
Variable Density Flow ◽  
Density Flow ◽  
Type Flow ◽  
Land Mass ◽  
The Impact

This paper reviews the analytical solutions for the impact of land reclamation on the ground water level and the saltwater interface with unconfined groundwater conditions in coastal aquifers. The applicability of the analytical solutions is somewhat limited by assumptions such as Dupuit-type flow and the Ghyben-Herzberg relation. Variable-density flow and solute transport simulations conducted by the numerical code FEFLOW were used to evaluate the accuracy of these analytical solutions. Three field-scale hypothetical cases were simulated for the numerical verification. The results show that a seepage face occurs in the numerical results rather than in the analytical solutions, but only minor difference occurs between the numerical and analytical solutions. This implies that the analytical solutions are reasonable despite the used assumptions.

On the generation of instabilities in variable density flow

1994 ◽  
Vol 30 (4) ◽  
pp. 913-927 ◽  
Author(s):  
Robert A. Schincariol ◽  
Franklin W. Schwartz ◽  
Carl A. Mendoza
Keyword(s):  
Variable Density ◽  
Variable Density Flow ◽  
Density Flow
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