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Title: Introduction to Groundwater Modelling


1
Introduction to Groundwater Modelling
C. P. Kumar Scientist F
National Institute of Hydrology Roorkee 247667
(Uttaranchal) India Email cpkumar_at_yahoo.com Webp
age http//www.angelfire.com/nh/cpkumar/
2
Presentation Outline
  • Groundwater in Hydrologic Cycle
  • Why Groundwater Modelling is needed?
  • Mathematical Models
  • Modelling Protocol
  • Model Design
  • Calibration and Validation
  • Groundwater Flow Models
  • Groundwater Modelling Resources

3
Groundwater in Hydrologic Cycle
4
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5
Types of Terrestrial Water
Surface Water
Soil Moisture
Ground water
6
Pores Full of Combination of Air and Water
Unsaturated Zone / Zone of Aeration / Vadose
(Soil Water)
Zone of Saturation (Ground water)
Pores Full Completely with Water
7
Groundwater
Important source of clean water More abundant
than SW
Baseflow
Linked to SW systems Sustains flows in streams
8
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9
Groundwater Concerns?
pollution
groundwater mining subsidence
10
  • Problems with groundwater
  • Groundwater overdraft / mining / subsidence
  • Waterlogging
  • Seawater intrusion
  • Groundwater pollution

11
Why Groundwater Modelling is needed?
12
  • Groundwater
  • An important component of water resource systems.
  • Extracted from aquifers through pumping wells and
    supplied for domestic use, industry and
    agriculture.
  • With increased withdrawal of groundwater, the
    quality of groundwater has been continuously
    deteriorating.
  • Water can be injected into aquifers for storage
    and/or quality control purposes.

13
  • Management of a groundwater system, means making
    such decisions as
  • The total volume that may be withdrawn annually
    from the aquifer.
  • The location of pumping and artificial recharge
    wells, and their rates.
  • Decisions related to groundwater quality.
  • Groundwater contamination by
  • Hazardous industrial wastes
  • Leachate from landfills
  • Agricultural activities such as the use of
    fertilizers and pesticides

14
  • MANAGEMENT means making decisions to achieve
    goals without violating specified constraints.
  • Good management requires information on the
    response of the managed system to the proposed
    activities.
  • This information enables the decision-maker, to
    compare alternative actions and to ensure that
    constraints are not violated.
  • Any planning of mitigation or control measures,
    once contamination has been detected in the
    saturated or unsaturated zones, requires the
    prediction of the path and the fate of the
    contaminants, in response to the planned
    activities.
  • Any monitoring or observation network must be
    based on the anticipated behavior of the system.

15
  • A tool is needed that will provide this
    information.
  • The tool for understanding the system and its
    behavior and for predicting this response is the
    model.
  • Usually, the model takes the form of a set of
    mathematical equations, involving one or more
    partial differential equations. We refer to such
    model as a mathematical model.
  • The preferred method of solution of the
    mathematical model of a given problem is the
    analytical solution.

16
  • The advantage of the analytical solution is that
    the same solution can be applied to various
    numerical values of model coefficients and
    parameters.
  • Unfortunately, for most practical problems,
    because of the heterogeneity of the considered
    domain, the irregular shape of its boundaries,
    and the non-analytic form of the various
    functions, solving the mathematical models
    analytically is not possible.
  • Instead, we transform the mathematical model into
    a numerical one, solving it by means of computer
    programs.

17
Prior to determining the management scheme for
any aquifer
We should have a CALIBRATED MODEL of the aquifer,
especially, we should know the aquifers natural
replenishment (from precipitation and through
aquifer boundaries).
The model will provide the response of the
aquifer (water levels, concentrations, etc.) to
the implementation of any management alternative.
We should have a POLICY that dictates management
objectives and constraints.
Obviously, we also need information about the
water demand (quantity and quality, current and
future), interaction with other parts of the
water resources system, economic information,
sources of pollution, effect of changes on the
environment---springs, rivers,...
18
  • GROUND WATER MODELING
  • WHY MODEL?
  • To make predictions about a ground-water
  • systems response to a stress
  • To understand the system
  • To design field studies
  • Use as a thinking tool

19
Use of Groundwater models
  • Can be used for three general purposes
  • To predict or forecast expected artificial or
    natural changes in the system. Predictive is more
    applied to deterministic models since it carries
    higher degree of certainty, while forecasting is
    used with probabilistic (stochastic) models.

20
Use of Groundwater models
  • To describe the system in order to analyse
    various assumptions
  • To generate a hypothetical system that will be
    used to study principles of groundwater flow
    associated with various general or specific
    problems.

21
ALL GROUND-WATER HYDROLOGY WORK IS MODELING A
Model is a representation of a system. Modeling
begins when one formulates a concept of a
hydrologic system, continues with application
of, for example, Darcy's Law to the problem,
and may culminate in a complex numerical
simulation.
22
Ground Water Flow Modelling
  • A Powerful Tool
  • for furthering our understanding of
    hydrogeological systems
  • Importance of understanding ground water flow
    models
  • Construct accurate representations of
    hydrogeological systems
  • Understand the interrelationships between
    elements of systems
  • Efficiently develop a sound mathematical
    representation
  • Make reasonable assumptions and simplifications
  • Understand the limitations of the mathematical
    representation
  • Understand the limitations of the interpretation
    of the results

23
Introduction to Ground Water Flow Modelling
  • Predicting heads (and flows) and
  • Approximating parameters
  • Solutions to the flow equations
  • Most ground water flow models are solutions of
    some form of the ground water flow equation
  • The partial differential equation needs to be
    solved to calculate head as a function of
    position and time, i.e., hf(x,y,z,t)
  • e.g., unidirectional, steady-state flow within a
    confined aquifer

24
Groundwater Modeling
  • The only effective way to test effects of
    groundwater management strategies
  • Takes time, money to make model
  • Conceptual model Steady state model
    Transient model
  • The model is only as good as its calibration

25
  • Processes we might want to model
  • Groundwater flow
  • calculate both heads and flow
  • Solute transport requires information on flow
    (velocities)
  • calculate concentrations

26
MODELING PROCESS ALL IMPORTANT
MECHANISMS PROCESSES MUST BE INCLUDED IN THE
MODEL, OR RESULTS WILL BE INVALID.
27
TYPES OF MODELS CONCEPTUAL MODEL QUALITATIVE
DESCRIPTION OF SYSTEM "a cartoon of the system
in your mind" MATHEMATICAL MODEL MATHEMATICAL
DESCRIPTION OF SYSTEM SIMPLE - ANALYTICAL
(provides a continuous solution over the model
domain) COMPLEX - NUMERICAL (provides a discrete
solution - i.e. values are calculated at only a
few points) ANALOG MODEL e.g. ELECTRICAL
CURRENT FLOW through a circuit board with
resistors to represent hydraulic conductivity and
capacitors to represent storage
coefficient PHYSICAL MODEL e.g. SAND TANK which
poses scaling problems
28
Mathematical Models
29
  • Mathematical model
  • simulates ground-water flow and/or solute fate
    and transport indirectly by means of a set of
    governing equations thought to represent the
    physical processes that occur in the system.
  • (Anderson and Woessner, 1992)

30
  • Components of a Mathematical Model
  • Governing Equation
  • (Darcys law water balance equation) with head
    (h) as the dependent variable
  • Boundary Conditions
  • Initial conditions (for transient problems)

31
Derivation of the Governing Equation
Q
R ?x ?y
q
?z
?x
?y
  • Consider flux (q) through REV
  • OUT IN - ?Storage
  • Combine with q -K grad h

32
Law of Mass Balance Darcys Law
Governing Equation for Groundwater Flow
-------------------------------------------------
-------------- div q - Ss (?h ??t)
(Law of Mass Balance) q - K grad h
(Darcys Law) div (K grad h)
Ss (?h ??t)
(Ss S / ? z)
33
General governing equation for steady-state,
heterogeneous, anisotropic conditions, without a
source/sink term
with a source/sink term
34
General governing equation for transient,
heterogeneous, and anisotropic conditions
Specific Storage Ss ?V / (?x ?y ?z ?h)
35
?h
?h
b
S V / A ? h S Ss b
Confined aquifer
Unconfined aquifer
Storativity
Specific yield
Figures taken from Hornberger et al. (1998)
36
General 3D equation
2D confined
2D unconfined
Storage coefficient (S) is either storativity or
specific yield. S Ss b T K b
37
  • Types of Solutions of Mathematical Models
  • Analytical Solutions h f(x,y,z,t)
  • (example Theis equation)
  • Numerical Solutions
  • Finite difference methods
  • Finite element methods
  • Analytic Element Methods (AEM)

38
Limitations of Analytical Models
  • The flexibility of analytical modeling is limited
    due to simplifying assumptions
  • Homogeneity, Isotropy, simple geometry, simple
    initial conditions
  • Geology is inherently complex
  • Heterogeneous, anisotropic, complex geometry,
    complex conditions
  • This complexity calls for a more
  • powerful solution to the flow equation ?
    Numerical modeling

39
Numerical Methods
  • All numerical methods involve representing the
    flow domain by a limited number of discrete
    points called nodes.
  • A set of equations are then derived to relate the
    nodal values of the dependent variable such that
    they satisfy the governing PDE, either
    approximately or exactly.

40
  • Numerical Solutions
  • Discrete solution of head at selected nodal
    points.
  • Involves numerical solution of a set of
    algebraic
  • equations.

Finite difference models (e.g., MODFLOW) Finite
element models (e.g., SUTRA)
41
Finite Difference Modelling
  • 3-D Finite Difference Models
  • Requires vertical discretization (or layering) of
    model

K1
K2
K3
K4
42
  • Finite difference models
  • may be solved using
  • a computer program
  • (e.g., a FORTRAN program)
  • a spreadsheet (e.g., EXCEL)

43
Finite Elements basis functions, variational
principle,
Galerkins method, weighted residuals
  • Nodes plus elements elements defined by nodes
  • Properties (K, S) assigned to elements
  • Nodes located on flux boundaries
  • Able to simulate point sources/sinks at nodes
  • Flexibility in grid design
  • elements shaped to boundaries
  • elements fitted to capture detail
  • Easier to accommodate anisotropy that occurs at
    an
  • angle to the coordinate axis

44
Hybrid Analytic Element Method (AEM)
Involves superposition of analytic solutions.
Heads are calculated in continuous space using a
computer to do the mathematics involved in
superposition.
The AE Method was introduced by Otto Strack. A
general purpose code, GFLOW, was developed
by Stracks student Henk Haitjema, who also wrote
a textbook on the AE Method Analytic Element
Modeling of Groundwater Flow, Academic Press,
1995.
Currently the method is limited to
steady-state, two-dimensional, horizontal flow.
45
Modelling Protocol
46
What is a model?
  • Any device that represents approximation to
    field system
  • Physical Models
  • Mathematical Models
  • Analytical
  • Numerical

47
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48
Modelling Protocol
  • Establish the Purpose of the Model
  • Develop Conceptual Model of the System
  • Select Governing Equations and Computer Code
  • Model Design
  • Calibration
  • Calibration Sensitivity Analysis
  • Model Verification
  • Prediction
  • Predictive Sensitivity Analysis
  • Presentation of Modeling Design and Results
  • Post Audit
  • Model Redesign

49
Purpose - What questions do you want the model to
answer?
  • Prediction System Interpretation Generic
    Modeling
  • What do you want to learn from the model?
  • Is a modeling exercise the best way to answer the
    question? Historical data?
  • Can an analytical model provide the answer?

System Interpretation Inverse Modeling
Sensitivity Analysis Generic Used in a
hypothetical sense, not necessarily for a real
site
50
Model Overkill?
  • Is the vast labor of characterizing the system,
    combined with the vast labor of analyzing it,
    disproportionate to the benefits that follow?

51
ETHICS
  • There may be a cheaper, more effective approach
  • Warn of limitations

52
Conceptual ModelEverything should be made as
simple as possible, but not simpler. Albert
Einstein
  • Pictorial representation of the groundwater flow
    system
  • Will set the dimensions of the model and the
    design of the grid
  • Parsimony.conceptual model has been simplified
    as much as possible yet retains enough complexity
    so that it adequately reproduces system behavior.

53
Select Computer Code
  • Select Computer Model
  • Code Verification
  • Comparison to Analytical Solutions Other
    Numerical Models
  • Model Design
  • Design of Grid, selecting time steps, boundary
    and initial conditions, parameter data set

Steady/Unsteady..1, 2, or 3-D
Heterogeneous/Isotropic..Instantaneous/Continuou
s
54
Calibration
  • Show that Model can reproduce field-measured
    heads and flow (concentrations if contaminant
    transport)
  • Results in parameter data set that best
    represents field-measured conditions.

55
Calibration Sensitivity Analysis
  • Uncertainty in Input Conditions
  • Determine Effect of Uncertainty on Calibrated
    Model

56
Model Verification
  • Use Model to Reproduce a Second Set of Field Data
  • Prediction
  • Desired Set of Conditions
  • Sensitivity Analysis
  • Effect of uncertainty in parameter values and
    future stresses on the predicted solution

57
Presentation of Modelling Design and Results
  • Effective Communication of Modeling Effort
  • Graphs, Tables, Text etc.

58
Postaudit
  • New field data collected to determine if
    prediction was correct
  • Site-specific data needed to validate model for
    specific site application
  • Model Redesign
  • Include new insights into system behavior

59
NUMERICAL MODELING DISCRETIZE Write equations
of GW Flow between each node Darcy's
Law Conservation of Mass Define Material
Properties Boundary Conditions Initial
Conditions Stresses At each node either H or Q
is known, the other is unknown n equations n
unknowns solve simultaneously with matrix
algebra Result H at each known Q node Q at
each known H node Calibrate Steady
State Transient Validate Sensitivity Pr
edictions Similar Process for Transport Modeling
only Concentration and Flux is unknown
60
NUMERICAL MODELING
61
Model Design
62
MODELs NEED Geometry Material Properties (K, S,
T, Fe, R, etc.) Boundary Conditions (Head, Flux,
Concentration etc.) Stress - changing boundary
condition
63
Model Design
  • Conceptual Model
  • Selection of Computer Code
  • Model Geometry
  • Grid
  • Boundary array
  • Model Parameters
  • Boundary Conditions
  • Initial Conditions
  • Stresses

64
Concept Development
  • Developing a conceptual model is the initial and
    most important part of every modelling effort. It
    requires thorough understanding of hydrogeology,
    hydrology and dynamics of groundwater flow.

65
Conceptual Model A descriptive representation of
a groundwater system that incorporates an
interpretation of the geological hydrological
conditions. Generally includes information about
the water budget. May include information on
water chemistry.
66
Selection of Computer Code
  • Which method will be used depends largely on the
    type of problem and the knowledge of the model
    design.
  • Flow, solute, heat, density dependent etc.
  • 1D, 2D, 3D

67
Model Geometry
  • Model geometry defines the size and the shape of
    the model. It consists of model boundaries, both
    external and internal, and model grid.

68
Boundaries
  • Physical boundaries are well defined geologic and
    hydrologic features that permanently influence
    the pattern of groundwater flow (faults, geologic
    units, contact with surface water etc.)

69
Boundaries
  • Hydraulic boundaries are derived from the
    groundwater flow net and therefore artificial
    boundaries set by the model designer. They can be
    no flow boundaries represented by chosen stream
    lines, or boundaries with known hydraulic head
    represented by equipotential lines.

70
HYDRAULIC BOUNDARIES
A streamline (flowline) is also a hydraulic
boundary because by definition, flow is ALWAYS
parallel to a streamflow. It can also be said
that flow NEVER crosses a streamline therefore
it is similar to an IMPERMEABLE (no flow)
boundary BUT Stress can change the flow pattern
and shift the position of streamlines therefore
care must be taken when using a streamline as the
outer boundary of a model.
71
TYPES OF MODEL BOUNDARY
NO-FLOW BOUNDARY Neither HEAD nor FLUX
is Specified. Can represent a Physical boundary
or a flow Line (Groundwater Divide)
SPECIFIED HEAD OR CONSTANT HEAD BOUNDARY h
constant q is determined by the model. And may be
ve or ve according to the hydraulic gradient
developed
72
TYPES OF MODEL BOUNDARY (contd)
SPECIFIED FLUX BOUNDARY q constant h is
determined by the model (The common method of
simulation is to use one injection well for
each boundary cell)
HEAD DEPENDANT BOUNDARY hb constant q c (hb
hm) and c f (K,L) and is called CONDUCTANCE hm
is determined by the model and its interaction
with hb
73
Boundary Types Specified Head/Concentration a
special case of constant head (ABC, EFG)
Constant Head /Concentration could replace
(ABC, EFG) Specified Flux could be recharge
across (CD) No Flow (Streamline) a special
case of specified flux (HI) Head Dependent
Flux could replace (ABC, EFG) Free Surface
water-table, phreatic surface (CD) Seepage
Face pressure atmospheric at ground surface
(DE)
74
Boundary conditions in Modflow
  • Constant head boundary
  • Head dependent flux
  • River Package
  • Drain Package
  • General-head Boundary Package
  • Known Flux
  • Recharge
  • Evapotranspiration
  • Wells
  • Stream
  • No Flow boundaries

75
Initial Conditions
  • Values of the hydraulic head for each active and
    constant-head cell in the model. They must be
    higher than the elevation of the cell bottom.
  • For transient simulation, heads to resemble
    closely actual heads (realistic).
  • For steady state, only hydraulic heads in
    constant head-cell must be realistic.

76
Model Parameters
  • Time
  • Space (layer top and bottom)
  • Hydrogeologic characteristics (hydraulic
    conductivity, transmissivity, storage parameters
    and effective porosity)

77
Time
  • Time parameters are specified when modelling
    transient (time dependent) conditions. They
    include time unit, length and number of time
    steps.
  • Length of stress periods is not relevant for
    steady state simulations

78
Grid
  • In Finite Difference model, the grid is formed by
    two sets of parallel lines that are orthogonal.
    The blocks formed by these lines are called
    cells. In the centre of each cell is the node
    the point at which the model calculates hydraulic
    head. This type of grid is called block-centered
    grid.

79
Grid
  • Grid mesh can be uniform or custom, a uniform
    grid is better choice when
  • Evenly distributed aquifer characteristics data
  • The entire flow field is equally important
  • Number of cells and size is not an issue

80
Grid
  • Grid mesh can be custom when
  • There is less or no data for certain areas
  • There is specific interest in one or more smaller
    areas
  • Grid orientation is not an issue in isotropic
    aquifers. When the aquifer is anisotropic, the
    model coordinate axes must be aligned with the
    main axes of the hydraulic conductivity.

81
  • Regular vs irregular grid spacing

Irregular spacing may be used to obtain detailed
head distributions in selected areas of the grid.
Finite difference equations that use
irregular grid spacing have a higher associated
error than FD equations that use regular grid
spacing.
82
Considerations in selecting the size of the grid
spacing
Variability of aquifer characteristics (K,T,S)
Variability of hydraulic parameters (R, Q)
Curvature of the water table
Vertical change in head
Desired detail around sources and sinks (e.g.,
rivers)
83
MODEL GRIDS
84
Grids
  • It is generally agreed that from a practical
    point-of-view the differences between grid types
    are minor and unimportant.
  • USGS MODFLOW employs a body-centred grid.

85
Boundary array (cell type)
  • Three types of cells
  • Inactive cells through which no flow into or out
    of the cells occurs during the entire time of
    simulation.
  • Active, or variable-head cells are free to vary
    in time.
  • Constant-head cell, model boundaries with known
    constant head.

86
Hydraulic conductivity and transmissivity
  • Hydraulic conductivity is the most critical and
    sensitive modelling parameter.
  • Realistic values of storage coefficient and
    transmissivity, preferably from pumping test,
    should be used.

87
Effective porosity
  • Required to calculate velocity, used mainly in
    solute transport models

88
Calibration and Validation
89
Calibration parameters are uncertain
parameters whose values are adjusted during model
calibration.
Identify calibration parameters and their
reasonable ranges.
Typical calibration parameters include hydraulic
conductivity and recharge rate.
90
In a real-world problem, we need to establish
model specific calibration criteria and define
targets including associated error.
Calibration Targets
associated error
calibration value
???0.80 m
20.24 m
Target with smaller associated error.
Target with relatively large associated error.
91
Targets used in Model Calibration
  • Head measured in an observation well is known
    as a target.
  • The simulated head at the node representing the
    observation well is compared with the measured
    head.
  • During model calibration, parameter values are
    adjusted until the simulated head matches the
    observed value.
  • Model calibration solves the inverse problem.

92
Calibration to Fluxes
  • When recharge rate (R) is a calibration
    parameter, calibrating to fluxes can help in
    estimating K and/or R.

93
In this example, flux information helps calibrate
K.
q KI
K ?
H1
H2
94
In this example, discharge information helps
calibrate R.
R ?
95
Calibration - Remarks
  • Calibrations are non-unique.
  • A good calibration does not ensure that the
    model will make good predictions.
  • You can never have enough field data.

  • Modelers need to maintain a healthy skepticism
  • about their results.
  • Need for an uncertainty analysis to accompany
  • calibration results and predictions.

96
Uncertainty in the Calibration
Involves uncertainty in
  • Targets
  • Parameter values
  • Conceptual model including boundary conditions,
  • zonation, geometry etc.

97
Ways to analyze uncertainty in the calibration
Sensitivity analysis is used as an uncertainty
analysis after calibration.
Use an inverse model (automated calibration) to
quantify uncertainties and optimize the
calibration.
98
Uncertainty in the Prediction
  • Reflects uncertainty in the calibration.
  • Involves uncertainty in how parameter values
  • (e.g., recharge) will vary in the future.

99
Ways to quantify uncertainty in the prediction
Sensitivity analysis
Stochastic simulation
100
Model Validation
How do we validate a model so that we have
confidence that it will make accurate predictions?
101
Modeling Chronology
1960s Flow models are great! 1970s
Contaminant transport models are great!
1975 What about uncertainty of flow models?
1980s Contaminant transport models dont work.
(because of failure to account for
heterogeneity)
1990s Are models reliable?
102
The objective of model validation is to
determine how well the mathematical
representation of the processes describes the
actual system behavior in terms of the degree of
correlation between model calculations and actual
measured data.
103
How to build confidence in a model Calibration
(history matching) Verification
requires an independent set of field
data Post-Audit requires waiting for
prediction to occur Models as interactive
management tools
104
KEEPING AN OPEN MIND Consider all dimensions of
the problem before coming to a conclusion. Consid
ering all the stresses that might be imposed and
all the possible processes that might be involved
in a situation before reaching a
conclusion. KEEPING AN OPEN MIND is spending 95
of your TIME DETERMINING WHAT YOU THINK IS
HAPPENING and only 5 of your TIME DEFENDING YOUR
OPINION. AVOID the common human TRAP of
REVERSING THOSE PERCENTAGES.
105
Groundwater Flow Models
106
  • Groundwater Flow Models
  • The most widely used numerical groundwater flow
    model is MODFLOW which is a three-dimensional
    model, originally developed by the U.S.
    Geological Survey.
  • It uses finite difference scheme for saturated
    zone.
  • The advantages of MODFLOW include numerous
    facilities for data preparation, easy exchange of
    data in standard form, extended worldwide
    experience, continuous development, availability
    of source code, and relatively low price.
  • However, surface runoff and unsaturated flow are
    not included, hence in case of transient
    problems, MODFLOW can not be applied if the flux
    at the groundwater table depends on the
    calculated head and the function is not known in
    advance.

107
  • MODFLOW
  • ? USGS code
  • ? Finite Difference Model
  • MODFLOW 88
  • MODFLOW 96
  • MODFLOW 2000

108
  • MODFLOW
  • (Three-Dimensional Finite-Difference
    Ground-Water Flow Model)
  • When properly applied, MODFLOW is the recognized
    standard model.
  • Ground-water flow within the aquifer is simulated
    in MODFLOW using a block-centered
    finite-difference approach.
  • Layers can be simulated as confined, unconfined,
    or a combination of both.
  • Flows from external stresses such as flow to
    wells, areal recharge, evapotranspiration, flow
    to drains, and flow through riverbeds can also be
    simulated.

109
  • MT3D
  • (A Modular 3D Solute Transport Model)
  • MT3D is a comprehensive three-dimensional
    numerical model for simulating solute transport
    in complex hydrogeologic settings.
  • MT3D is linked with the USGS groundwater flow
    simulator, MODFLOW, and is designed specifically
    to handle advectively-dominated transport
    problems without the need to construct refined
    models specifically for solute transport.

110
FEFLOW (Finite Element Subsurface Flow
System) FEFLOW is a finite-element package for
simulating 3D and 2D fluid density-coupled flow,
contaminant mass (salinity) and heat transport in
the subsurface. HST3D (3-D Heat and Solute
Transport Model) The Heat and Solute Transport
Model HST3D simulates ground-water flow and
associated heat and solute transport in three
dimensions.
111
  • SEAWAT
  • (Three-Dimensional Variable-Density Ground-Water
    Flow)
  • The SEAWAT program was developed to simulate
    three-dimensional, variable- density, transient
    ground-water flow in porous media.
  • The source code for SEAWAT was developed by
    combining MODFLOW and MT3D into a single program
    that solves the coupled flow and solute-transport
    equations.

112
  • SUTRA
  • (2-D Saturated/Unsaturated Transport Model)
  • SUTRA is a 2D groundwater saturated-unsaturated
    transport model, a complete saltwater intrusion
    and energy transport model.
  • SUTRA employs a two-dimensional hybrid
    finite-element and integrated finite-difference
    method to approximate the governing equations
    that describe the two interdependent processes.
  • A 3-D version of SUTRA has also been released.

113
  • SWIM
  • (Soil water infiltration and movement model)
  • SWIMv1 is a software package for simulating water
    infiltration and movement in soils.
  • SWIMv2 is a mechanistically-based model designed
    to address soil water and solute balance issues.
  • The model deals with a one-dimensional vertical
    soil profile which may be vertically
    inhomogeneous but is assumed to be horizontally
    uniform.
  • It can be used to simulate runoff, infiltration,
    redistribution, solute transport and
    redistribution of solutes, plant uptake and
    transpiration, evaporation, deep drainage and
    leaching.

114
  • VISUAL HELP
  • (Modeling Environment for Evaluating and
    Optimizing Landfill Designs)
  • Visual HELP is an advanced hydrological modeling
    environment available for designing landfills,
    predicting leachate mounding and evaluating
    potential leachate contamination.
  • Visual MODFLOW
  • (Integrated Modeling Environment for MODFLOW and
    MT3D)
  • Visual MODFLOW provides professional 3D
    groundwater flow and contaminant transport
    modeling using MODFLOW and MT3D.

115
Groundwater Modelling Resources
116
Groundwater Modeling Resources
  • Kumar Links to Hydrology Resources
  • http//www.angelfire.com/nh/cpkumar/hydrology.html
  • USGS Water Resources Software Page
  • water.usgs.gov/software
  • Richard B. Winstons Home Page
  • www.mindspring.com/rbwinston/rbwinsto.htm
  • Geotech Geoenviron Software Directory
  • www.ggsd.com
  • International Ground Water Modeling Center
  • www.mines.edu/igwmc

117
Ground Water Modelling Discussion Group An
email discussion group related to ground water
modelling and analysis. This group is a forum for
the communication of all aspects of ground water
modelling including technical discussions
announcement of new public domain and commercial
softwares calls for abstracts and papers
conference and workshop announcements and
summaries of research results, recent
publications, and case studies. Group home page
http//groups.yahoo.com/group/gwmodel/ Post
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118
Visual MODFLOW Users Group Visual MODFLOW is a
proven standard for professional 3D groundwater
flow and contaminant transport modeling using
MODFLOW-2000, MODPATH, MT3DMS AND RT3D. Visual
MODFLOW seamlessly combines the standard Visual
MODFLOW package with Win PEST and the Visual
MODFLOW 3D-Explorer to give a complete and
powerful graphical modeling environment. This
group aims to provide a forum for exchange of
ideas and experiences regarding use and
application of Visual MODFLOW software. Group
home page http//in.groups.yahoo.com/group/visu
al-modflow/ Post message
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119
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