Introduction to Groundwater Modeling.pptx

7/25/2019 Introduction to Groundwater Modeling.pptx

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Introduction to Groundwater Modelling


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Presentation Outline

Groundwater in Hydrologic Cycle

Why Groundwater Modelling isneeded?

Mathematical Models

Modelling Protocol

Model Design

Calibration and Validation

Groundwater Flow Models

Groundwater Modelling esources


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Groundwater in Hydrologic Cycle


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Types of Terrestrial Water

Ground water

Soil

Moisture

SurfaceWater


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Unsaturated Zone / Zone of Aeration / Vadose

(Soil Water

!ores "ull of Co#$ination of Air and Water

Zone of Saturation (Ground water

!ores "ull Co#pletely wit% Water


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Groundwater

portant source of clean water

More a$undant t%an SW

'ined to SW syste#s

Sustains flows

in strea#s

)aseflow


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pollution

Groundwater Concerns*

groundwater #ining

su$sidence


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Problems with groundwater

Groundwater o!erdra"t # mining # subsidence

Waterlogging

$eawater intrusion

Groundwater %ollution


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W%y Groundwater Modelling is needed*


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Groundwater

&n im%ortant com%onent o" water resource systems'

()tracted "rom a*ui"ers through %um%ing wells and

su%%lied "or domestic use+ industry and agriculture'

With increased withdrawal o" groundwater+ the *uality

o" groundwater has been continuously deteriorating'

Water can be in,ected into a*ui"ers "or storage and#or

*uality control %ur%oses'


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Manage#ent of a groundwater syste#+ #eans

#aing suc% decisionsas,

-he total !olume that may be withdrawn annually "rom the a*ui"er'

-he location o" %um%ing and arti"icial recharge wells+ and their

rates'

Decisions related to groundwater *uality'

Groundwater conta#ination $y,

Ha.ardous industrial wastes

/eachate "rom land"ills

&gricultural acti!ities such as the use o" "ertili.ers and %esticides


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M&0&G(M(0-means ma1ing decisionsto achie!e goalswithout

!iolating s%eci"ied constraints'

Good management re*uires in"ormation on the res%onse o" the

managed system to the %ro%osed acti!ities'

-his in"ormation enables the decision2ma1er+ to com%are alternati!e

actions and to ensure that constraints are not !iolated'

&ny %lanning o" mitigation or control measures+ once contamination

has been detected in the saturated or unsaturated .ones+ re*uires

the %rediction o" the %ath and the "ate o" the contaminants+ in

res%onse to the %lanned acti!ities'

&ny monitoring or obser!ation networ1 must be based on the

antici%ated beha!ior o" the system'


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& tool is needed that will %ro!ide this in"ormation'

-he tool "or understanding the system and its beha!ior

and "or %redicting this res%onse is the #odel'

3sually+ the model ta1es the "orm o" a set o"

mathematical e*uations+ in!ol!ing one or more %artial

di""erential e*uations' We re"er to such model as a

mathematical model'

-he %re"erred method o" solution o" the mathematicalmodel o" a gi!en %roblem is the analytical solution'


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-he ad!antage o" the analytical solution is that the

same solution can be a%%lied to !arious numerical!alues o" model coe""icients and %arameters'

3n"ortunately+ "or most %ractical %roblems+ because o"

the heterogeneity o" the considered domain+ the

irregular sha%e o" its boundaries+ and the non2analytic

"orm o" the !arious "unctions+ sol!ing the mathematical

models analytically is not %ossible'

Instead+ we trans"orm the mathematical model into anumerical one+ sol!ing it by means o" com%uter

%rograms'


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We should have a CALIBRATED MODELof the aquifer, especially,

e should !"o the aquifer#s "atural reple"ish$e"t %fro$precipitatio" a"d throu&h aquifer 'ou"daries()

*rior to deter$i"i"& the $a"a&e$e"t sche$e for a"yaquifer+

We should have a *OLIC that dictates $a"a&e$e"t o'-ectives

a"d co"strai"ts)

O'viously, e also "eed i"for$atio" a'out the ater de$a"d%qua"tity a"d quality, curre"t a"d future(,i"teractio" ith other

parts of the ater resources syste$, eco"o$ic i"for$atio", sources

of pollutio", effect of cha"&es o" the e"viro"$e"t...spri"&s, rivers,)))

The $odel ill provide the respo"se of the aquifer %ater levels,

co"ce"tratio"s, etc)( to the i$ple$e"tatio" of a"y $a"a&e$e"t

alter"ative)


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G-.U0 WAT1- M.01'&G

WH2 M.01'*

-o ma1e %redictions about a ground2water

system4s res%onse to a stress

-o understand the system

-o design "ield studies

3se as a thin1ing tool


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/se of 0rou"dater $odels

Can be used for three general purposes:

To predict or forecastexpected 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 withprobabilistic (stochastic) models.


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/se of 0rou"dater $odels

To describethe system in order to analyse

various assumptions

Togenerate a hypothetical system thatwill be used to study principles of

groundwater flow associated with various

general or specific problems.


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A'' G-.U03WAT1- H20-.'.G2 W.-4 &S M.01'&G

A Model is a representation of a syste#5

Modeling $egins w%en one for#ulates a concept of a

%ydrologic syste#+continues wit% application of+ for e6a#ple+

0arcy7s 'aw to t%e pro$le#+

and #ay

cul#inate in a co#ple6 nu#erical si#ulation5


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Ground Water "low Modelling

& Power"ul -ool"or "urthering our understanding

o" hydrogeological systems

Im%ortance o" understanding ground water "low models

Construct accurate re%resentations o" hydrogeological systems

3nderstand the interrelationshi%s between elements o"

systems

(""iciently de!elo% a sound mathematical re%resentation

Ma1e reasonable assum%tions and sim%li"ications

3nderstand the limitations o" the mathematical re%resentation

3nderstand the limitations o" the inter%retation o" the results


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&ntroduction to Ground Water "low Modelling

K

xqhxh 0)(

!redicting %eads 5and "lows6and

Appro6i#ating para#eters

$olutionsto the "low e*uations

Most ground water "low models are

solutions o" some "orm o" the

ground water "low e*uation

!otentio#etricSurface

)

))

ho

x0

h(x)

x

K q

7e'g'+ unidirectional+ steady2state "lowwithin a con"ined a*ui"er

-he %artial di""erential e*uation needs

to be sol!ed to calculate head as a

"unction o" %osition and time+

i'e'+ h8"5)+y+.+t6

h5x,y,z,t6?

K

xqhhdx

K

qdh

K

q

dx

dh xh

h

000

Darcy4s /aw Integrated


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-he only e""ecti!e way to test e""ects o"

groundwater management strategies

-a1es time+ money to ma1e model

Conce%tual model

$teady state model

-ransient model

-he model is only as good as its calibration

Groundwater Modeling


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Processes we might want to model

Groundwater "low

calculate both heads and flow

$olute trans%ort9 re*uires in"ormation

on "low 5!elocities6 calculate concentrations


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M.01'&G !-.C1SS

A'' &M!.-TAT M1CHA&SMS 8 !-.C1SS1S MUST


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T2!1S ." M.01'S

C.C1!TUA' M.01'9UA'&TAT&V1

01SC-&!T&. ." S2ST1M

:a cartoon of t%e syste# in your #ind:

MATH1MAT&CA' M.01'

MATH1MAT&CA' 01SC-&!T&. ."

S2ST1MS&M!'13 AA'2T&CA' (pro;ides a continuous solution o;er t%e #odel do#ain

C.M!'1


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Mat%e#atical Models


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Mathematical model:

simulates ground2water "low and#orsolute "ate and trans%ort indirectly by

means o" a set o" go!erning e*uationsthought to re%resent the %hysical%rocesses that occur in the system'

5&nderson and Woessner+ ;


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Com%onents o" a Mathematical Model

Go!erning (*uation

5Darcy4s law > water balance e*uation6

with head 5h6 as the de%endent !ariable

oundary Conditions

Initial conditions5"or transient

%roblems6


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) y @

y

)

.

;' Consider "lu) 5q6 through (V

=' O3- 9 I0 8 2 $torage

A' Combine with:q8 2B gradh

*

0eri;ation of t%e Go;erning 1=uation


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'aw of Mass )alance> 0arcy?s 'aw @

Go;erning 1=uation for Groundwater "low

333333333333333333333333333333333333333333333333333333333333333

divq8 2 $s 5ht6 (Law of Mass Balance)

q8 2 4grad h (Darcys Law)

div 54grad h6 8 $s 5ht6

5$s 8 $ # .6


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1(%(%(% =

+

+

h!

y

h!

yx

h!

xyx

General go!erning e*uation

"or steady2state+ heterogeneous+ anisotro%ic

conditions+ without a source#sin1 term

2(%(%(% "

h!

y

h!

yx

h!

xyx =

+

+

with a source#sin1 term


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2(%(%(% "

t

h#

h!

y

h!

yx

h!

x

syx

=

+

+

General go!erning e*uation "or transient+

heterogeneous+ and anisotro%ic conditions

$%eci"ic $torage

$s8 V # 5) y . h6


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Figures ta1en "rom Hornberger et al' 5;


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2(%(%(% "t

h#

h!

y

h!

yx

h!

xsyx

=

+

+

"t

h#

y

hT

yx

hT

xyx

=

+

(%(%

"t

h#

y

hh!

yx

hh!

xyx

=

+

(%(%

=D con"ined:

=D uncon"ined:

$torage coe""icient 5$6 is either storati!ity or s%eci"ic yield'

$ 8 $sb - 8 B b

General AD e*uation


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-y%es o" $olutions o" Mathematical Models

&nalytical $olutions: h8 "5)+y+.+t6

5e)am%le: -heis e*uation6

0umerical $olutions

Finite di""erence methods

Finite element methods

&nalytic (lement Methods 5&(M6


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-he "le)ibility o" analytical modeling is

limiteddue to sim%li"ying assum%tions:

Homogeneity+ Isotro%y+ sim%le geometry+

sim%le initial conditionsE

Geology is inherently com%le):

Heterogeneous+ anisotro%ic+ com%le)

geometry+ com%le) conditionsE

-his com%le)ity calls "or a more

%ower"ul solution to the "low e*uation 0umerical modeling

/imitations o" &nalytical Models


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Numerical Methods

h All numerical methods involverepresenting the flow domain by alimited number of discrete points called

nodes.h A set of equations are then derived to

relate the nodal values of thedependent variable such that they

satisfy the governing PDE, eitherapproimately or eactly.


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0umerical $olutions

Discrete solution o" head at selected nodal %oints'

In!ol!es numerical solution o" a set o" algebraic

e*uations'

Finite di""erence models5e'g'+ MODF/OW6

Finite element models5e'g'+ $3-&6


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"inite 0ifference Modelling

A2D Finite Di""erence Models

e*uires !ertical discreti.ation 5or layering6 o" model

B;B=BA

B


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"inite 1le#ents, basis "unctions+ !ariational %rinci%le+ Galer1in4s method+ weighted residuals

0odes %lus elements elements de"ined by nodes

0odes located on "lu) boundaries

Fle)ibility in grid design:

elements sha%ed to boundaries

elements "itted to ca%ture detail

(asier to accommodate anisotro%y that occurs at an

angle to the coordinate a)is

&ble to simulate %oint sources#sin1s at nodes

Pro%erties 5B+ $6 assigned to elements


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In!ol!es su%er%osition o" analytic solutions' Heads are

calculated in continuous s%ace using a com%uter to do

the mathematics in!ol!ed in su%er%osition'

Hybrid

Analytic 1le#ent Met%od (A1M

-he &( Method was introduced by Otto $trac1'

& general %ur%ose code+ GF/OW+ was de!elo%ed by

$trac14s student Hen1 Hait,ema+ who also wrote a

te)tboo1 on the &( Method: Analytic Element Modeling

of Groundwater Flow+ &cademic Press+ ;


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What is a model?

&ny 7de!iceJ that re%resents a%%ro)imation

to "ield system

Physical Models Mathematical Models

&nalytical

0umerical


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Modelling Protocol

(stablish the Pur%ose o" the Model De!elo% Conce%tual Model o" the $ystem $elect Go!erning (*uations and Com%uter Code Model Design

Calibration Calibration $ensiti!ity &nalysis Model Veri"ication Prediction

Predicti!e $ensiti!ity &nalysis Presentation o" Modeling Design and esults Post &udit Model edesign

Purpose What questions do you want the


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Purpose - What questions do you want the

model to answer?

Prediction $ystem Inter%retation Generic

Modeling

What do you want to learn "rom the model? Is a modeling e)ercise the best way to

answer the *uestion? Historical data?

Can an analytical model %ro!ide the answer?

Syste# &nterpretation, &n;erse Modeling, Sensiti;ity

Analysis

Generic, Used in a %ypot%etical sense+ not necessarily

for a real site

Syste# &nterpretation, &n;erse Modeling, Sensiti;ity

Analysis

Generic, Used in a %ypot%etical sense+ not necessarily

for a real site


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Model Overkill?

Is the !ast labor o" characteri.ing the system+combined with the !ast labor o" analy.ing it+disproportionateto the bene"its that "ollow?


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E!"#$

-here may be a chea%er+ more e""ecti!e

a%%roach

Warn o" limitations


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#onceptual ModelEverything should be made as simple as possible, but not simpler. Albert

Einstein

Pictorial re%resentation o" the groundwater

"low system

Will set the dimensions o" the model andthe design o" the grid

7ParsimonyJE'conce%tual model has been

sim%li"ied as much as %ossible yet retains

enough com%le)ity so that it ade*uatelyre%roduces system beha!ior'


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$elect #omputer #ode

$elect Com%uter Model Code Veri"ication

Com%arison to &nalytical $olutions Other

0umerical Models Model Design

Design o" Grid+ selecting time ste%s+

boundary and initial conditions+ %arameter

data set

Steady/Unsteady55+ B+ or 30D E

Heterogeneous/&sotropicE55&nstantaneous/Continuous

Steady/Unsteady55+ B+ or 30D E

Heterogeneous/&sotropicE55&nstantaneous/Continuous


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#ali%ration

$how that Model can re%roduce "ield2

measured heads and "low 5concentrations i"

contaminant trans%ort6

esults in %arameter data set that best

re%resents "ield2measured conditions'


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#ali%ration $ensitivity &nalysis

3ncertainty in In%ut Conditions

Determine (""ect o" 3ncertainty on

Calibrated Model


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Model 'eri(ication

3se Model to e%roduce a $econd $et o"

Field Data

Prediction Desired $et o" Conditions

$ensiti!ity &nalysis (""ect o" uncertainty in %arameter !alues and

"uture stresses on the %redicted solution


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Presentation o( Modelling

)esign and *esults (""ecti!e Communication o"

Modeling (""ort

Gra%hs+ -ables+ -e)t etc'


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Postaudit

0ew "ield data collected to

determine i" %rediction was correct

$ite2s%eci"ic data needed to

!alidate model "or s%eci"ic sitea%%lication

Model *edesign

Include new insights into system

beha!ior

UM1-&CA' M.01'&G


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UM1-&CA' M.01'&G

0&SC-1T&Z1

Write e=uations of GW "low $etween eac% node

0arcy7s 'aw

Conser;ation of Mass

0efine Material !roperties

)oundary Conditions

&nitial Conditions

Stresses

At eac% node eit%er H or 9 is nown+t%e ot%er is unnownn e=uations 8 n unnowns

sol;e si#ultaneously wit% #atri6 alge$ra

-esult H at eac% nown 9 node

9 at eac% nown H node

Cali$rate Steady State

Transient

Validate

Sensiti;ity

!redictions

Si#ilar !rocess for Transport Modeling only Concentration and "lu6 is unnown

UM1-&CA' M.01'&G


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UM1-&CA' M.01'&G


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Model 0esign


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M.01's 110

Geo#etry

Material !roperties (4+ S+ T+ Fe+ -+ etc5

)oundary Conditions (Head+ "lu6+ Concentration etc5

Stress 3 c%anging $oundary condition


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Model Desi&"

Conceptual Model

Selection of Computer Code

Model Geometry

Grid

Boundary array

Model Parameters

Boundary Conditions Initial Conditions

Stresses


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Co"cept Develop$e"t

$eveloping a conceptual model is the initial

and most importantpart of every modelling

effort. %t re&uires thorough understanding ofhydrogeology, hydrology and dynamics of

groundwater flow.


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Conceptual Model

A descriptive representationof a groundwater system that

incorporates an interpretation of thegeological & hydrological conditions.Generally includes information about

the water budget. May includeinformation on water chemistry.


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3electio" of Co$puter Code

'hich method will be used depends largely

on the type of problem and the nowledge of

the model design. low, solute, heat, density dependent etc.

*$, +$, $


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Model 0eo$etry

-odel geometry defines the sie and the

shape of the model. %t consists of model

boundaries, both external and internal, andmodel grid.


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Bou"daries

Physical boundariesare well defined

geologic and hydrologic features that

permanently influence the pattern ofgroundwater flow (faults, geologic units,

contact with surface water etc.)


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Bou"daries

Hydraulic boundariesare derived from the

groundwater flow net and therefore

artificial/ boundaries set by the modeldesigner. They can be no flow boundaries

represented by chosen stream lines, or

boundaries with nown hydraulic headrepresented by e&uipotential lines.

H20-AU'&C ).U0A-&1S


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& streamline5"lowline6 is also a

hydraulic boundary because by

de"inition+ "low is &/W&K$%arallel to a stream"low' It can

also be said that "low 0(V(

crosses a streamline there"ore it

is similar to an IMP(M(&/(

5no "low6 boundary

)UT

$tress can change the "low

%attern and shi"t the %osition o"streamlines there"ore care must

be ta1en when using a

streamline as the outer boundary

o" a model'

T2!1S ." M.01' ).U0A-2


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.3"'.W ).U0A-2

0either H(&D nor F/3 is

$%eci"ied' Can re%resent a

Physical boundary or a "low

/ine 5Groundwater Di!ide6

S!1C&"&10 H1A0 .-

C.STAT H1A0 ).U0A-2

h 8 constant

* is determined by the model'

&nd may be >!e or 9!e accordingto the hydraulic gradient de!elo%ed

T2!1S ." M.01' ).U0A-2 (cont?d


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(

S!1C&"&10 "'U< ).U0A-2

* 8 constant

h is determined by the model

5-he common method o" simulation

is to use one in,ection well "or each

boundary cell6

H1A0 01!10AT ).U0A-2

hb8 constant

* 8 c 5hb9 hm6

and c 8 " 5B+/6 and is called

CO0D3C-&0C(hmis determined by the model and

its interaction with hb

)oundary Types


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Specified Head/Concentration, a special case of constant %ead (A)C+ 1"G

Constant Head /Concentration, could replace (A)C+ 1"G

Specified "lu6, could $e rec%arge across (C0

o "low (Strea#line, a special case of specified flu6 (H&

Head 0ependent "lu6, could replace (A)C+ 1"G

"ree Surface, water3ta$le+ p%reatic surface (C0

Seepage "ace, pressure @ at#osp%eric at ground surface (01


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Bou"dary co"ditio"s i" Modflo

Constant head boundary

0ead dependent flux "iver Pacage

$rain Pacage 1eneral2head 3oundary Pacage

!nown lux "echarge

4vapotranspiration

'ells #tream

5o low boundaries


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I"itial Co"ditio"s

6alues of the hydraulic head for each activeand constant2head cell in the model. They

must be higher than the elevation of the cellbottom.

or transient simulation, heads to resembleclosely actual heads (realistic).

or steady state, only hydraulic heads inconstant head2cell must be realistic.


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Model *ara$eters

Time

#pace (layer top and bottom)

0ydrogeologic characteristics(hydraulic conductivity, transmissivity,

storage parameters and effective porosity)


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Ti$e

Time parameters are specified when

modelling transient (time dependent)

conditions. They include time unit, lengthand number of time steps.

7ength of stress periods is not relevant for

steady state simulations


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0rid

%n inite $ifference model, the grid is

formed by two sets of parallel lines that are

orthogonal. The blocs formed by theselines are called cells. %n the centre of each

cell is the node 8 the point at which the

model calculates hydraulic head. This type

of grid is called bloc2centered grid.


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0rid

1rid mesh can be uniform or custom, a

uniform grid is better choice when

4venly distributed a&uifer characteristics data The entire flow field is e&ually important

5umber of cells and sie is not an issue


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0rid

1rid mesh can be custom when

There is less or no data for certain areas

There is specific interest in one or more smaller

areas

1rid orientation is not an issue in isotropic

a&uifers. 'hen the a&uifer is anisotropic,

the model coordinate axes must be alignedwith the main axes of the hydraulic

conductivity.


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-egular ;s irregular grid spacing

Irregular s%acing may be used to obtain

detailed head distributions in selected areas

o" the grid'

Finite di""erence e*uations that use irregular

grid s%acing ha!e a higher associated error

than FD e*uations that use regular grid s%acing'


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Cur!ature o" the water table

Vertical change in head

Variability o" a*ui"er characteristics 5B+-+$6

Variability o" hydraulic %arameters 5+ @6

Considerations in selecting t%e sie of

t%e grid spacing

Desired detail around sources and sin1s 5e'g'+ ri!ers6

M.01' G-&0S


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M.01' G-&0S


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!rids

h "t is generally agreed that from a practicalpoint#of#view the differences between gridtypes are minor and unimportant.

h $%!% M&D'(&) employs a body#centred grid.


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Bou"dary array %cell type(

Three types of cells

%nactive cells through which no flow into or out

of the cells occurs during the entire time ofsimulation.

9ctive, or variable2head cells are free to vary in

time.

Constant2head cell, model boundaries with

nown constant head.

4 d li d i i d


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4ydraulic co"ductivity a"d

tra"s$issivity

0ydraulic conductivity is the most criticaland sensitive modelling parameter.

"ealistic values of storage coefficient andtransmissivity, preferably from pumping test,

should be used.


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Effective porosity

"e&uired to calculate velocity, used mainlyin solute transport models


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Cali$ration and Validation


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Calibration %arametersare uncertain %arameters

whose !alues are ad,usted during model calibration'

-y%ical calibration %arameters include hydraulic

conducti!ity and recharge rate'

Identi"y calibration %arameters and their reasonable

ranges'

In a real2world %roblem+ we need to establish model


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Calibration -argets

cali$ration;alue

associated error

=L'= m

+/L'L m

-arget with relati!ely

large associated error'

-arget with smallerassociated error'

s%eci"ic calibration criteria and de"ine targets including

associated error'

-argets used in Model Calibration


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Head measured in an obser!ation well is 1nownas a target'

-argets used in Model Calibration

-he simulated head at the node re%resenting the

obser!ation well is com%ared with the measured

head'

During model calibration+ %arameter !alues are

ad,usted until the simulated head matches the

obser!ed !alue'

Model calibration sol!es the in!erse %roblem'


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Cali'ratio" to 5lu6es

Whe" rechar&e rate %R( is a cali'ratio"

para$eter, cali'rati"& to flu6es ca" help i"esti$ati"& 7 a"d8or R)

In this example flux information


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K = ?

H; H=

* 8 BI

In this example, flux informationhelps calibrate .

In this example discharge


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R = ?

In this example, dischargeinformation helps calibrate !.

Calibration 2 emar1s


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Calibration emar1s

Calibrations are non2uni*ue'

& good calibration does not ensure that

the model will ma1e good %redictions'

0eed "or an uncertainty analysisto accom%any

calibration results and %redictions'

Kou can ne!er ha!e enough "ield

data' Modelers need to maintain a healthy s1e%ticism

about their results'

3ncertainty in the Calibration


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3ncertainty in the Calibration

In!ol!es uncertainty in:

Parameter !alues

Conce%tual model including boundary conditions+

.onation+ geometry etc'

-argets


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Ways to analy.e uncertainty

in the calibration

$ensiti!ity analysisis used as an uncertainty

analysis a"ter calibration'

3se an in!erse model 5automated calibration6

to *uanti"y uncertainties and o%timi.e the

calibration'


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3ncertainty in the Prediction

In!ol!es uncertainty in how %arameter !alues

5e'g'+ recharge6 will !ary in the "uture'

e"lects uncertainty in the calibration'


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$tochastic

simulation

Ways to *uanti"y uncertainty

in the %rediction

$ensiti!ity analysis


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Model Validation

How do we 7!alidateJ a model so that

we ha!e con"idence that it will ma1eaccurate %redictions?

Modeling C%ronology


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Modeling C%ronology

;


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7-he ob,ecti!e o" #odel ;alidationis to

determine how well the mathematical

re%resentation o" the %rocesses describes

the actual system beha!ior in terms o" thedegree o" correlation between model

calculations and actual measured dataJ'


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How to $uild confidence in a #odel

Calibration 5history matching6

7Veri"icationJ

re*uires an inde%endent set o" "ield data

Post2&udit: re*uires waiting "or %rediction to occur

Models as interacti!e management tools

411!&G A .!1 M&0


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411!&G A .!1 M&0

Consider all di#ensions of t%e pro$le# $efore co#ing

to a conclusion5

Considering all t%e stresses t%at #ig%t $e i#posed and

all t%e possi$le processes t%at #ig%t $e in;ol;ed in a

situation $efore reac%ing a conclusion5

411!&G A .!1 M&0 is spending IJ of your

T&M1 01T1-M&&G WHAT 2.U TH&4 &S HA!!1&G

and only IJ of your T&M1 01"10&G 2.U- .!&&.5

AV.&0 t%e co##on %u#an T-A! of -1V1-S&G

TH.S1 !1-C1TAG1S5


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Groundwater "low Models



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The most widely used numerical roundwater flow model isM!"F#!$ which is a three%dimensional model& oriinallyde'eloped y the *S* Geoloical Sur'ey*

It uses finite difference scheme for saturated +one*

The ad'antaes of M!"F#!$ include numerous facilitiesfor data preparation& easy e,chane of data in standardform& e,tended worldwide e,perience& continuousde'elopment& a'ailaility of source code& and relati'ely lowprice*

-owe'er& surface runoff and unsaturated flow are notincluded& hence in case of transient prolems& M!"F#!$can not e applied if the flu, at the roundwater taledepends on the calculated head and the function is not.nown in ad'ance*


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M.0"'.W

USGS code

"inite 0ifference Model

M.0"'.W KK

M.0"'.W L M.0"'.W B

M!"F#!$


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(Three%"imensional Finite%"ifference Ground%$ater Flow

Model)

$hen properly applied& M!"F#!$ is the reconi+ed

standard model*

Ground%water flow within the a/uifer is simulated in

M!"F#!$ usin a loc.%centered finite%difference

approach*

#ayers can e simulated as confined& unconfined& or a

comination of oth*

Flows from e,ternal stresses such as flow to wells& areal

rechare& e'apotranspiration& flow to drains& and flow

throuh ri'ereds can also e simulated*

MT0"


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(1 Modular 0" Solute Transport Model)

MT0" is a comprehensi'e three%dimensional numerical

model for simulatin solute transport in comple,

hydroeoloic settins*

MT0" is lin.ed with the SGS roundwater flow simulator&

M!"F#!$& and is desined specifically to handle

ad'ecti'ely%dominated transport prolems without the needto construct refined models specifically for solute transport*

F2F#!$


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(Finite 2lement Susurface Flow System)

F2F#!$ is a finite%element pac.ae for simulatin 0" and 3"

fluid density%coupled flow& contaminant mass (salinity) and

heat transport in the susurface*

-ST0"

(0%" -eat and Solute Transport Model)

The -eat and Solute Transport Model -ST0" simulates

round%water flow and associated heat and solute transport in

three dimensions*


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S21$1T

(Three%"imensional 4ariale%"ensity Ground%$ater Flow)

The S21$1T proram was de'eloped to simulate three%

dimensional& 'ariale% density& transient round%water flowin porous media*

The source code for S21$1T was de'eloped y cominin

M!"F#!$and MT0"into a sinle proram that sol'esthe coupled flow and solute%transport e/uations*

ST51
http://water.usgs.gov/software/modflow-88.htmlhttp://hydro.geo.ua.edu/mt3d/mt3dhome.htmhttp://hydro.geo.ua.edu/mt3d/mt3dhome.htmhttp://water.usgs.gov/software/modflow-88.html


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(3%" Saturated6nsaturated Transport Model)

ST51 is a 3" roundwater saturated%unsaturated

transport model& a complete saltwater intrusion and enery

transport model*

ST51 employs a two%dimensional hyrid finite%element

and interated finite%difference method to appro,imate the

o'ernin e/uations that descrie the two interdependent

processes*

1 0%" 'ersion of ST51 has also een released*

S$IM


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(Soil water infiltration and mo'ement model)

S$IM'7 is a software pac.ae for simulatin water

infiltration and mo'ement in soils*

S$IM'3 is a mechanistically%ased model desined to

address soil water and solute alance issues*

The model deals with a one%dimensional 'ertical soil

profile which may e 'ertically inhomoeneous ut is

assumed to e hori+ontally uniform*

It can e used to simulate runoff& infiltration&redistriution& solute transport and redistriution of

solutes& plant upta.e and transpiration& e'aporation& deep

drainae and leachin*

4IS1# -2#P

(M d li 2 i t f 2 l ti d ! ti i i


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(Modelin 2n'ironment for 2'aluatin and !ptimi+in

#andfill "esins)

4isual -2#P is an ad'anced hydroloical modelin

en'ironment a'ailale for desinin landfills& predictin

leachate moundin and e'aluatin potential leachate

contamination*

4isual M!"F#!$

(Interated Modelin 2n'ironment for M!"F#!$ and

MT0")

4isual M!"F#!$ pro'ides professional 0" roundwater

flow and contaminant transport modelin usin

M!"F#!$ and MT0"*


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Groundwater Modelling -esources


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Groundwater Modeling esources

Bumar /in1s to Hydrology esourceshtt%:##www'angel"ire'com#nh#c%1umar#hydrology'html

3$G$ Water esources $o"tware Page

water'usgs'go!#so"tware

ichard ' Winston4s Home Pagewww'minds%ring'com#rbwinston#rbwinsto'htm

Geotech Geoen!iron $o"tware Directorywww'ggsd'com

International Ground Water Modeling Centerwww'mines'edu#igwmc

Ground Water Modelling Discussion Grou%
http://www.mines.edu/igwmchttp://www.mines.edu/igwmc


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Ground Water Modelling Discussion Grou%

&n email discussion grou% related to ground water modelling and

analysis' -his grou% is a "orum "or the communication o" all as%ects

o" ground water modelling including technical discussions

announcement o" new %ublic domain and commercial so"twares calls

"or abstracts and %a%ers con"erence and wor1sho% announcementsand summaries o" research results+ recent %ublications+ and case

studies'

Grou% home %age : htt%:##grou%s'yahoo'com#grou%#gwmodel#

Post message : gwmodelQyahoogrou%s'com$ubscribe : gwmodel2subscribeQyahoogrou%s'com

3nsubscribe : gwmodel2unsubscribeQyahoogrou%s'com

/ist owner : gwmodel2ownerQyahoogrou%s'com

Visual MODF/OW 3sers Grou%


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Visual MODF/OW is a %ro!en standard "or %ro"essional AD

groundwater "low and contaminant trans%ort modeling using

MODF/OW2=LLL+ MODP&-H+ M-ADM$ &0D -AD' Visual

MODF/OW seamlessly combines the standard Visual MODF/OW

%ac1age with Win P($- and the Visual MODF/OW AD2()%lorer to gi!e

a com%lete and %ower"ul gra%hical modeling en!ironment'

-his grou% aims to %ro!ide a "orum "or e)change o" ideas and

e)%eriences regarding use and a%%lication o" Visual MODF/OW

so"tware'

Grou% home %age : htt%:##in'grou%s'yahoo'com#grou%#!isual2mod"low#

Post message : !isual2mod"lowQyahoogrou%s'co'in

$ubscribe : !isual2mod"low2subscribeQyahoogrou%s'co'in

3nsubscribe : !isual2mod"low2unsubscribeQyahoogrou%s'co'in

/ist owner : !isual2mod"low2ownerQyahoogrou%s'co'in


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"A##$ M%'((I)G

-H&0B$

Documents

Introduction to Groundwater Modeling.pptx