Numerical Modeling of Contaminant Transport through Soils: Case Study

Al-Najjar, M M; Evans, Brian Mark

doi:10.1061/(asce)1090-0241(2008)134:2(214)

Cited by 10 publications

(13 citation statements)

References 26 publications

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“…The model accounts for the effects of swelling and shrinking of the media on the flow and transport, by adopting the hydraulic properties using constitutive relationships. Javadi et al (2008) presented a numerical model for predicting two dimensional contaminant transport and flow of water and air through unsaturated soils. In the model, the nonlinear system of governing differential equations was solved using a finite element method in the space domain and a finite difference scheme in the time domain.…”

Section: Numerical Studiesmentioning

confidence: 99%

Contaminant transport through porous media: An overview of experimental and numerical studies

Patil¹,

Chore²

2014

Advances in environmental research

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The groundwater has been a major source of water supply throughout the ages. Around 50% of the rural as well as urban population in the developing countries like India depends on groundwater for drinking. The groundwater is also an important source in the agriculture and industrial sector. In many parts of the world, groundwater resources are under increasing threat from growing demands, wasteful use and contamination. A good planning and management practices are needed to face this challenge. A key to the management of groundwater is the ability to model the movement of fluids and contaminants in the subsurface environment. It is obvious that the contaminant source activities cannot be completely eliminated and perhaps our water bodies will continue to serve as receptors of vast quantities of waste. In such a scenario, the goal of water quality protection efforts must necessarily be the control and management of these sources to ensure that released pollutants will be sufficiently attenuated within the region of interest and the quality of water at points of withdrawal is not impaired. In order to understand the behaviour of contaminant transport through different types of media, several researchers are carrying out experimental investigations through laboratory and field studies. Many of them are working on the analytical and numerical studies to simulate the movement of contaminants in soil and groundwater of the contaminant transport. With the advent of high power computers especially, a numerical modelling has gained popularity and is indeed of particular relevance in this regard. This paper provides the state of the art of contaminant transport and reviews the allied research works carried out through experimental investigation or using the analytical solution and numerical method. The review involves the investigation in respect of both, saturated and unsaturated, porous media.

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Section: Numerical Studiesmentioning

confidence: 99%

Contaminant transport through porous media: An overview of experimental and numerical studies

Patil¹,

Chore²

2014

Advances in environmental research

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“…The governing differential equations for water flow and air flow in terms of two primary variables; pore water pressure (u w ) and pore air pressure (u a ) can be expressed as (Javadi et al, 2008).…”

Section: Governing Equations Of Fluid Flowmentioning

confidence: 99%

“…The governing differential equation of solute transport in unsaturated soil can be written based on conservation of mass as (Javadi et al, 2008):…”

Section: Governing Equation Of Solute Transportmentioning

confidence: 99%

“…Numerical solution of fluid flow equations The governing differential equations for water flow and air flow were defined in Section 2, in terms of two primary unknowns; u w and u a . The spatial discretization of the governing differential equation for water flow and air flow can be written as ( Javadi et al, 2008):…”

Section: Modelling Of Seawater Intrusionmentioning

confidence: 99%

“…In equation (3) the term in the left hand side is the rate of change of solute mass in the control volume. In the right hand side of the equation, the first two terms represent the effect of advection, the following four terms represent the effect of mechanical dispersion in pore water and pore air, the seventh term shows the effect of adsorption/desorption of solute on the solid skeleton of the soil and the last term represents the effect of radioactive decay or biodegradation (Javadi et al, 2008). In this equation v wx and v wy are the components of apparent groundwater velocity in the x-and …”

Section: Governing Equation Of Solute Transportmentioning

confidence: 99%

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Finite element modelling of seawater intrusion in Wadi Ham aquifer, UAE

Sherif¹,

Abd-Elhamid²

2012

Engineering Computations

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Purpose -Seawater intrusion represents a major problem in many coastal aquifers all over the world. It degrades the water-quality and hence the groundwater may become unsuitable for domestic and agriculture purposes. Due to the direct hydraulic contact between the freshwater and saline water in coastal aquifers and the density difference between the two water bodies, the seawater migrates inland. The problem is exacerbated when the groundwater abstraction rates exceed the natural recharge from rainfall events. The key to controlling this problem is to maintain the proper balance between water being pumped from the aquifer and the amount of water recharging it. The purpose of this paper is to present a coupled transient finite element model for simulation of fluid flow and solute transport in soils with application to study seawater intrusion in coastal aquifers. Design/methodology/approach -The model includes coupling of fluid flow and solute transport. Transient density-dependent flow and the dependency of dispersion on velocity are considered. After validation, the model is applied to predict the seawater intrusion in the Wadi Ham aquifer, UAE in vertical sections and the results are compared with those from a commercial code (SEWAT) which was used to simulate seawater intrusion in the aquifer in a horizontal section. Findings -A good agreement is observed between the results of the current model in the vertical cross-section and those of SEWAT in the horizontal cross-section for the case of Wadi Ham. The results show that the model can predict the extent of seawater intrusion (and the transition zone) and distribution of salt concentration in the aquifer with a good accuracy. Originality/value -The developed model includes coupling of fluid flow and solute transport in saturated and unsaturated porous media. Transient density-dependent flow and the dependency of dispersion on velocity are considered. The model has been applied to a real world case study. A combination of the results in vertical and horizontal sections has been used to build a 3D picture of seawater intrusion in the aquifer. IntroductionGroundwater constitutes the main source for water supply in many areas of the globe. The remarkable increase of the world population associated with the agricultural and industrial development, has created additional demand for freshwater. The increased abstraction of fresh water from aquifers has contributed to the depletion of groundwater resources. Seawater intrusion is one of the major problems in coastal aquifers. Due to the direct hydraulic contact between the freshwater and saline water in coastal aquifers and the density difference between the two water bodies, the seawater migrates inland. The problem is more severe in arid regions where the groundwater pumping rates exceed the natural recharge from rainfall events. The problem of seawater intrusion is influenced by a number of parameters including, among others, the geometry of the aquifer, type of aquifer, geological setting of the system, hydrogeolog...

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A simulation‐optimization model to control seawater intrusion in coastal aquifers using abstraction/recharge wells

Javadi

Abd-Elhamid

Farmani

2011

Num Anal Meth Geomechanics

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Seawater intrusion is one of the most serious environmental problems in many coastal regions all over the world. Mixing a small quantity of seawater with groundwater makes it unsuitable for use and can result in abandonment of aquifers. Therefore, seawater intrusion should be prevented or at least controlled to protect groundwater resources. This paper presents development and application of a simulationoptimization model to control seawater intrusion in coastal aquifers using different management scenarios; abstraction of brackish water, recharge of freshwater, and combination of abstraction and recharge. The model is based on the integration of a genetic algorithm optimisation technique and a coupled transient density-dependent finite element model. The objectives of the management scenarios include determination of the optimal depth, location and abstraction/recharge rates for the wells to minimize the total costs for construction and operation as well as salt concentrations in the aquifer. The developed model is applied to analyze the control of seawater intrusion in a hypothetical confined coastal aquifer. The efficiencies of the three management scenarios are examined and compared. The results show that combination of abstraction and recharge wells is significantly better than using abstraction wells or recharge wells alone as it gives the least cost and least salt concentration in the aquifer. The results from this study would be useful in designing the system of abstraction/recharge wells to control seawater intrusion in coastal aquifers and can be applied in areas where there is a risk of seawater intrusion.

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Numerical Modeling of Contaminant Transport through Soils: Case Study

Cited by 10 publications

References 26 publications

Contaminant transport through porous media: An overview of experimental and numerical studies

Contaminant transport through porous media: An overview of experimental and numerical studies

Finite element modelling of seawater intrusion in Wadi Ham aquifer, UAE

A simulation‐optimization model to control seawater intrusion in coastal aquifers using abstraction/recharge wells

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