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Numerical Modelinggof Vadose Zone Processes(with focus on HYDRUS Software Packages)

Outline

Modeling->> Scientific Modeling-> Mathematical Modeling-> Numerical Modelingg-> Modeling of Vadose Zone Processes

HYDRUS Family
F il off Models
M d l andd Modules:
M d lJirka Šimůnek
Š
Department of Environmental Sciences,
University of California,
California Riverside,
Riverside CA(with contributions from)- HP1/HP2- UnsatChem- Wetland- DualPerm- Fumigants- C-Ride

Miroslav Šejna1, Diederik Jacques2, Günter Langergraber3,
Scott Bradford4, and Rien van Genuchten5
1PC-Progress, Ltd., Prague, Czech Republic
2Belgian Nuclear Research Centre (SCK•CEN), Mol, Belgium
3University of Natural Resources and Life Sciences, Vienna (BOKU University), Austria
4US Salinity Laboratory, USDA, ARS, Riverside, CA, USA
5Federal University of Rio de Janeiro, Brazil

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- general biogeochemical module- transportpof major
j ions- C and N processes- preferential flow and transport- transport of fumigants- colloid-facilitated solute transport

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Modeling

Scientific Modeling

The process of creating abstract or conceptual models
 Sculpting - to create a form from a substance such as clay
 Fashion Modeling - to display objects (clothing) for others to see Molecular Modeling - to mimic the behavior of molecules
 Modeling Psychology - a typet
off behaviorb h i learnedld throughthhScientific Modeling is the process of generating various
abstract, physical, graphical, conceptual, and/or
mathematical models.

observation of others demonstrating the same behavior



Physical Models - to make a miniature model of an technical artifact
S i ifi Modeling
ScientificM d li - the process of creating abstract or conceptualmodels and their use in the creation of predictive statements.

A Scientific Model is a simplified abstract view of acomplex reality, in which empirical objects, phenomena,and physical processes are represented in a logical way
byy ggraphicalpobjects,j, abstract ideas,, or mathematicalequations.
A GraphicalpModel is a p
probabilistic
model, in which a graph denotes theconditional dependence structure
between random variables.

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Physical Models in Hydrology
Mostly used before the development and wide use of numericalhydrological models.

Example of a Physical Groundwater Model
Photo Credit: West Virginia Conservation Agency

Conceptual Model
Conceptual Model - formed after a conceptualization process
in the mind.
Conceptual Model - used to help us know and understand thesubject matter they represent.
Conceptual Modeling is the activity of formally describing
some aspects
t off ththe physicalh i l andd social
i l world
ld aroundd us forf thethpurposes of understanding and communication.

Water flow in the plant-soilatmosphere system

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A colloid-facilitated solute transport

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Mathematical Modeling

Analytical Models

A Mathematical Model is a description of a physicalsystemyusing
g mathematical concepts
p and language.
g g

Analytical Models represent a classical mathematical approach
to solve mathematical equations, leading to an exact solution
for a particular problem.
problemFlow and transport processes in the vadose zone are usuallydescribed using various partial differential equations.

Analytical Models usually result in an explicit equation thatstates that concentration ((or water content or temperature)p) isequal to a certain value at a particular time and location.

Water flow, and solute and heattransport in the plant-soil-atmospheresystem (HYDRUS-1D)

Colloid-Facilitated Solute Transport(C-Ride Module)
Co B ( x, t )  Ci A( x, t )  1  A( x, t )  B( x, t ) 
0  t  toc ( x, t )  C  B( x, t )  B( x, t  t )   C A( x, t )   1  A( x, t )  B( x, t )  t  to
o
i

 o

where
 ( Rx  vt )2 v 2t
 Rx  vt  t   1
A( x, t )  exp    1  erfc    DR exp   4 DRt  R  2
 2 DRt 
1  vx v 2t  Rx  vt  vx 
 1   exp   erfc 
2 
D DR 
D
 2 DRt  
B ( x, t ) vv
 Rx  ut  Rx  ut  (v  u ) x  (v  u ) x 
exp
p
f 
expp 
f 
 erfc erfcuv
 2D 
 2D 
 2 DRt  u  v
 2 DRt 2v
 Rx  vt  vx  t 
exp    erfc 

2 D
D R
 2 DRt 

Observed ((circles)) and fitted ((solid line))
breakthrough curves for boron transport
through a 30 cm long soil column filledwith Glendale clay loam (van Genuchten,1974).

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STANMODSTANMOD (1D Applications)

Computer Software for Evaluating Solute Transport in
Porous Media Using Analytical Solutions of the ConvectionDi
Dispersion
i E
Equationti

Inverse Analysis

J. Šimůnek, M. Th. van Genuchten, M. Šejna, N. Toride, and F. J. Leij

A powerful and very versatile Windowsbased software package.
One-DimensionalOne
Dimensional Transport Models:
CFITM [van Genuchten, 1980]
CFITIM [van Genuchten, 1981]
CHAIN [[van Genuchten,, 1985]]
CXTFIT2 [Toride et al., 1995]
SCREEN [Jury et al., 1987]
Two/Three-Dimensional Transport Models:
3DADE [Leij and Bradford, 1994]
N3DADE [Leij and Toride, 1995]

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Deterministic Analysis

Stochastic Analysis

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STANMOD (1D Applications)

STANMOD (2D Applications)

Direct Analysis

Retardation Factor

Mass Transfer Coefficient

Cross-Section

Observation Nodes

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Analytical Models

Numerical Modeling Using Analytical Solutions one can often more easily evaluateTime and space is divided into small pieces (e.g., finite
differences, finite elements, finite volumes) and thegoverning equations are integrated over these pieces.

interrelationships among parameters and get better insight into
how various processes control the basic flow and transport
processes.

 Analytical Solutions are often used to check the correctness andaccuracy of numerical models.

 Many Analytical Solutions lead to relatively complicatedformulations that include infinite series and/or integrals.

 AnalyticalA l ti l Solutions
S l tican usuallyll beb derivedd i d only
l for
f simplified
i lifi dtransport systems involving linearized governing equations,homogeneous soils, simplified geometries of the transportdomain,, and constant or highly
g y simplifiedpinitial and boundaryyconditions.

 For more complex situations, such as for transient water flow or

nonequilibriumqsolute transportpwith nonlinear reactions,,
Analytical Solutions are generally not available and/or cannot bederived, in which case Numerical Models must be employed.

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Numerical Models
 Numerical Methods are superior to Analytical Methods interms of being able to solve practical problems.

 Numerical Methods allow users- to design complicated geometries that reflect complex naturalgeologic and hydrologic conditions,- to control parameters in space and time,- to prescribe realistic initial and boundary conditions, and- to implement nonlinear constitutive relationships.
 Numerical Methods usually- subdivide the time and spatial coordinates into smaller pieces,such as finite differences, finite elements, or finite volumes, and- reformulate the continuous form of governing partial
diffdifferential
i l equationsiini terms off a system off algebraic
l b i eqs.
 In order to obtain solutions at certain times, Numerical
Methods generally require intermediate simulations (timestepping)ti ) betweenb tth
the iinitial
iti l condition
diti andd theth pointsi t ini timeti
for which the solution is needed.

HYDRUS (1D/2D/3D)
Software for Simulating Water Flow and
Solute Transport in One/Two/Three Di
Dimensionalil Variably-Saturated
V i bl S t
t dS
Soils
il
Using Numerical Solutions- thousandshd off users aroundd the
h world
ld- thousands of applications published- used by scientists, students, and/or practicing professionals

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HYDRUS-1D
Profile Information

New Features (computational modules)

All Fluxes

0

1.0

-500

0.5

-1000

0.0

-1500

-0.5

-2000

-1.0

-2500

-1.5

-3000

-2.0

0.0

0.1

0.2

0.3

0.4

0.5

Water Contents [-]

50

100

150

200

250

300

250

300

Time [days]

Observation Nodes

Cumulative Fluxes

200

60

potTop100

potRoot40

actTop200actRoot
actBot

-100

0

-200

-20

-300

-40
50

100

150

200

Time [days]

250

300

50

100

150

200

Time [days]

Software for Simulating Water Flow and Solute Transport in OneDimensional Variably-Saturated Soils Using Numerical Solutions

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Agricultural Applications
Precipitation
Irrigation
 Runoff Evaporation
 Transpiration
 Root Water Uptake
 Capillary Rise
 Deep Drainage

Industrial Applications
Industrial Pollution
Municipal Pollution
 Landfill
L dfill CoversC Waste Repositories
 Radioactive Waste
Disposal Sites
 Remediation
 Brine Releases
 Contaminant Plumes
 Seepage of Wastewaterfrom Land Treatment
Systems
 Emerging Pollutants(gasoline additives,
industrial additives,
personal hygiene
products flame
products,
retardants, explosives,surfactants)









Fertilizers
Pesticides
 Fumigants
 Emerging Pollutants(steroids and hormones,
pharmaceuticals)
 Colloids
 Pathogens
 NanoparticlesObservation wells

Source Zone
Control Planes

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Governing Equations

Environmental Applications

Variably-Saturated Water Flow (Richards Equation)

 Ecological Apps Heat Exchange andFluxes (including theSurface Energy Balance) Carbon Storage andFluxes Nutrient Transport
 Soil Respiration
 Microbiological
Processes
 Effects
Eff t off Cli
ClimatetChange Riparian Systems
S
A if
 Stream-Aquifer
Interactions

 ( h )   h    K ( h) 
 1    S ( h)
t
z 
 z

Solute Transport (Convection-Dispersion Equation) (  s )  ( c )  c  qc  D  

t
t
z 
z   z

Hillel (2003)

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Heat Movement (Conduction-Dispersion Equation)
C p ( )T  
T 
qqT
   ( ) Cw
 C w ST

t
z 
z 
z

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HYDRUS – Main Processes

HYDRUS – Solute Transport

Water Flow: Transport of Single Ions or Particles (colloids, viruses, bacteria) Transport of Multiple Ions (sequential first-order decay)

Richards equation for variably-saturated water flow
Various models of soil hydraulicyproperties
p pHysteresis
 Sink term, accounting for water uptake by plant roots(uncompensated and compensated; reduced due to osmotic and pressure stress)
 Preferential flow Isothermal and thermal liquid and vapor flow

Radionuclides:
 Nitrogen: Pesticides:

Solute Transport:













Convective-dispersiveptransportpin the liquid
q
p
phase
Diffusion in the gaseous phase
Linear and nonlinear interactions between the solid and liquid phases
Linear equilibrium reactions between the liquid and gaseous phases
Zero-order pproduction,, First-order degradationg
Physical and chemical nonequilibrium solute transport
Sink term, accounting for nutrient uptake by plant roots (active and passive)

Heat Transport:Conduction and convection with flowing water (transport of latent heat)

Inverse Optimization (of flow, transport, and reaction parameters)

238Pu -> 234U -> 230Th -> 226Ra(NH2)2CO -> NH4+ -> NO2- -> NO3aldicarb (oxime) -> sulfone (sulfone oxime) ->sulfoxide (sulfoxide oxime)

Chlorinated Hydrocarbons: PCE -> TCE -> c-DCE -> VC -> ethylene
Pharmaceuticals Hormones: Estrogen (17bEstradiol ->Pharmaceuticals,> Estrone ->> Estriol),
Estriol)
Testosterone



Explosives:

TNT (-> 4HADNT -> 4ADNT -> TAT), RDX, HMX

 Transport of Major Ions (the UNSATCHEM module) General BioGeoChemical Reactions (the HP1/2/3 module) Processes in Wetlands (the CW2D and CWM1 modules)
 Colloid-Facilitated Solute Transport (the C-Ride module)HYDRUS-1D

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Graphical
p
User Interface

HYDRUS (2D/3D)

Graphical
p
User Interface
GUI

Fitting of
BTC and RP

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HYDRUS (2D/3D) - Applications

HYDRUS (2D/3D) - Applications

Subsurface Drip
Irrigation System
SoilS
il watert contentt tsimulated as:
A. a Three
Three-Dimensional
Dimensional
system with multiple
point sources
B. a Two-Dimensional
system with a line
sourceC. An Axisymmetrical
two-dimensional
system with a point
source90 m

30 m

36 540 FE
36,540Kandelous, M. M., J. Šimůnek, M. Th. van Genuchten, and K. Malek, Soil water content distributions between twoemitters of a subsurface drip irrigation system, Soil Science Society of America Journal, 75(2), 488-497, 2011.

Pressure head profiles after 10, 25, 50, and 100 years.
Leak (2 mm diameter) at the bottom of the Palmdale Reservoir.

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HYDRUS (2D/3D) - Applications

HYDRUS (2D/3D) - Applications

129,461 FE
I415
411 m

61 m

1

2

3

4

5
0.0

0.1

Finite Element Mesh and Material Distribution
A two-dimensional transect, 411 m wide and 61 m deep, with a freeway in the middle

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0.2

0.3

0.4

0.5

0.6

0.7

Velocity Vectors
A two-dimensional transect, 411 m wide and 61 m deep, with a freeway in the middle

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HYDRUS (2D/3D) - Applications

HYDRUS (2D/3D) – Transport Domains
HYDRUS Geometries:
A.
A
B.
C.
D.
E.

2D – Simple
Si l
2D – General
3D – Simple
3D – Layered
3D – General

A

B

C

D

E

E

HYDRUS Levels:

Pressure Head Distribution
in a Three-Dimensional Transport Domain

2D – Lite (A)2D – Standard (A+B)
3D – Lite (A+C)
3 – Standard
3D
S(A(A+B+C+D)C )3D – Professional (All)To help protect y our priv acy , PowerPoint prev ented this external picture from being automatically downloaded. To download and display this picture, click Options in the Message Bar, and then click Enable external content.

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HYDRUS (2D/3D) - Geometries

HYDRUS (2D/3D) - Geometries

Discontinuous 3D Layers

Complex Drainage System

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HYDRUS: 3D-Professional
Infiltration Basin and Stream

HYDRUS (2D/3D) - Geometries
Import of complex Geometries (e.g., DXF, TIN, STL)To help protect y our priv acy , PowerPoint prev ented this external picture from being automatically downloaded. To download and display this picture, click Options in the Message Bar, and then click Enable external content.

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ParSWMS – Parallelized Version of HYDRUS
 ParSWMS (Hardelauf et al., 2007) - Parallelized version of

SWMS_3D, an earlier and simpler version of HYDRUS-3D.
 Developed by the Forschungszentrum in Jülich, Germany.
 MPI (Message-Passing Interface). LINUX or UNIX OSs.
 Test - Supercomputer with 41 SMP nodes with 32
processors each (total 1312 processors)
2D Water flow and solute transport (Hardelauf et al., 2007)
492 264 fi
492,264
finiteit elementlt nodesd

HYDRUS and its Modules
 HYDRUS + PHREEQC = HP1/2/3(hydrological + biogeochemical processes)

 HYDRUS + C-Ride(particle and p(pparticle-facilitated solute transport)p ) HYDRUS + DualPerm(preferential water flow and solute transport)

 HYDRUS + UNSATCHEM(hydrological + CO2 + major ion processes)
 HYDRUS + Wetland (CW2D/CWM1)
3D Water flow problem
275,706 finite element nodes(Herbst et al., 2008)

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(biogeochemical processes in constructed wetlands)

 HYDRUS + Fumigant(fate and transport of fumigants)

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HYDRUS and its Modules
 HYDRUS + PHREEQC = HP1/2/3(hydrological + biogeochemical processes)

 HYDRUS + C-Ride(particle and particle-facilitatedparticle facilitated solute transport)

 HYDRUS + DualPerm(preferential water flow and solute transport)(pp )HP1/2/3 (HYDRUS+PHREEQC)
Simulating water flow, transport and biogeochemical reactions in environmental
soil quality problems

A Coupledp
Numerical Code for
Variably Saturated Water Flow,
Solute Transport and
BioGeoChemistryin Soil Systems

 HYDRUS + UNSATCHEM(hydrological + CO2 + major ion processes)

 HYDRUS + Wetland (CW2D/CWM1)(biogeochemical processes in constructed wetlands)

 HYDRUS + Fumigant(fate and transport of fumigants)

Flow and transport model
HYDRUS-1D 4.0
HYDRUS (2D/3D) 2.x

Biogeochemical model
PHREEQC 2 4
PHREEQC-2.4

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HYDRUS GUI for HP1/2/3

HP1/2/3 (HYDRUS+PHREEQC)
HYDRUS--1D or HYDRUS (2D/3D):HYDRUSyVariably-Saturated
Water Flow
Solute Transport
 Heat Transport
 Gas Transport
 Root Water Uptake


PHREEQC [Parkhurst and Appelo,
Appelo, 1999]:
Available Chemical Reactions:Aqueous Complexation
Redox Reactions
 Ion Exchange (Gains-Thomas)
 Surface Complexation (diffuse double-layer model and nonelectrostatic surface complexation model)
 Precipitation/Dissolution
Precipitation/Dissol tion
 Chemical Kinetics
 Biological Reactions
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Jacques, D.,
Jacques
D and JJ. Šimůnek
Šimůnek, Notes on the HP1 software – a coupled code for variably-saturated
variably saturated water
flow, heat transport, solute transport and biogeochemistry in porous media, HP1 Version 2.2,
SCK•CEN-BLG-1068, Waste and Disposal, SCK•CEN, Mol, Belgium, 114 pp., 2010.

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Transport and Cation Exchange
Heavyy Metals

HYDRUS (2D/3D) GUI for HP2/3

Major ions (Ca, Na, Al, Cl) and Heavy Metals (Zn, Pb, Cd)
8E 0048E-004Cl

Conce ntration ((m ol/l)Conceentration (m ol/l)

0 01
0.01
0.008
Na

0.006

Ca

0.004
0.002
Al
0
0

3

6

9

Time (days)

Four text editors to define the geochemical model, required output, andsolution compositions are fully incorporated into the GUI.

12

15

Zn

6E-0044E-004Pb

2E-004Cd
0E 000
0E+000
0

3

6

9

12

15

Time (days)

A (8-cm) soil column is initially contaminated with heavy metals (in equilibrium with thecation exchanger). The column is then flushed with a CaCl2 solution without heavy metals.

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U-Transport in Agricultural Field Soils
4.2

80

CEC

60

Steady-state

4

SC

Total

pH

% U(VI) adsorbed

100

HP2 – Reclamation of a Sodic Soil

3.8

40

3.6

20

3.4

Atmospheric

5 cm depth
150

0
2

3

U-species replacedby other cations

4

5

6

pH
Increased deprotonation
Increased U-sorption

151

152

153

154 155 156
Time (year)

157

158

159

160

 Water content variations induce pH variations(dry soil => low pH)
 pH variations => variations in sorption potential(low pH => low sorption – higher mobility)

 Aqueous speciation reactions
C, Ca, Cl, F, H, K, Mg, N(5), Na, O(0), O(-2), P, S(6), U(6) Multi-site cation exchange reactions- Related to amount of organic matter- Increases with increasing pH- UO22+ adsorbs

 Surface complexation reactions- Specific binding to charged surfaces (FeOH)- Related to amount of Fe-oxides

Jacques et al., VZJ, 2008.

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Uranium Transport from a Mill Tailing Pile

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HP1 Examples
 Transport of Heavy Metals (Zn2+, Pb2+, and Cd2+) subject to a

multiple pH
pH-dependent
dependent Cation Exchange Transport and mineral dissolution of Amorphous SiO2 andGibbsite Infiltration of a Hyperalkaline Solution in a clay sample(kinetic precipitation-dissolution of kaolinite, illite, quartz, calcite,
dolomite, gypsum, hydrotalcite, and sepiolite)
 Kinetic biodegradation of NTA (biomass, cobalt)
 Long-term Uranium transport following mineral phosphorus
105*25 m
1560 FE
Aqueous Complexation for Uranium Species
Calcite and Gypsum Precipitation/Dissolution
Cation Exchange

ffertilizationtili ti (pH-dependent surface complexation and cation exchange) Transport of Explosives, such as TNT and RDX
 Property Changes (porosity/conductivity) due toprecipitation/ dissolution reactions

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HYDRUS and its Modules
 HYDRUS + PHREEQC = HP1/2/3(hydrological + biogeochemical processes)

 HYDRUS + C-Ride(particle and particle-facilitatedparticle facilitated solute transport)

 HYDRUS + DualPerm(preferential water flow and solute transport)(pp ) HYDRUS + UNSATCHEM(hydrological + CO2 + geochemical processes)

 HYDRUS + Wetland (CW2D/CWM1)(biogeochemical processes in constructed wetlands)

 HYDRUS + Fumigant

Colloid-Facilitated Solute Transport Many contaminants should be relatively

immobile in the subsurface since under normal
conditions they are strongly sorbed to soil
 They can also sorb to colloids, which often moveat rates similar or faster as non-sorbing tracers
 Experimental evidence exists that many
contaminantst it are transportedtt d nott onlyl in
i a
dissolved state by water, but also sorbed tomovingg colloids
 Examples: heavy metals, radionuclides,
pesticides, viruses, pharmaceuticals, hormones,andd otherth contaminantst it(fate and transport of fumigants)

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HYDRUS + C-Ride Module

Colloid, Virus, and Bacteria Transport

 HYDRUSHYDRUS--1D and HYDRUS (2D/3D)- Variably-Saturated Water Flow
- Solute Transport- HeatH t Transport
Tt- Root Water Uptake

Air C-Ride (Šimůnek et al.,al 2006)- Particle Transport

Water

Mobile Colloids, Cc
kstr- colloids, bacteria, viruses, nanoparticles- attachment/detachment, straining, blocking- Particle-Facilitated Solute Transport- transport of solutes attached to particles

sstr
Strained Colloids, Scstr

Solid

kac

kdc

s
Attached Colloids, ScattTo help protect y our priv acy , PowerPoint prev ented this external picture from being automatically downloaded. To download and display this picture, click Options in the Message Bar, and then click Enable external content.

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Colloid-Facilitated Solute Transport

Particle-Facilitated Solute Transport
Pang et al. [2005]: Bacteria act as carriers for heavy
metals in gravel aquifers

AirmContaminant sorbed tomobilebil colloids,ll id Smc
kamc

Water

kstr

Kd

Solid

kdmc

Dissolved
Di
l dContaminant, C

Instantaneously Sorbed
Contaminant, Se

kac

kdc

kdic

Since bacteria may be excluded from small
pores they move through interconnected
pores,
larger pores and cracks where water moves
quicker.

kaic



i
Kinetically Sorbed
Contaminant, Sk

Since contaminantsSit it can sorbb tot thesethbacteria, they provide a vehicle for rapidtransport of less mobile contaminants.

Contaminant sorbed to immobile colloids, Sic

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Colloid-Facilitated Solute Transport
C-Ride Module

HYDRUS and its Modules
 HYDRUS + PHREEQC = HP1/2/3(hydrological + biogeochemical processes)

 HYDRUS + C-Ride(particle and particle-facilitatedparticle facilitated solute transport)

 HYDRUS + DualPerm(preferential water flow and solute transport)(pp ) HYDRUS + UNSATCHEM
Breakthrough curves forf colloidsi (black(line),i ) solute sorbed to colloidsi (blue(line), and dissolved solute (red line):
Left: solute and colloids are applied independently
Right: solute is initially attached to colloids
The Retardation Factor for colloids is equal to 1 and for solute to 4
Unit input concentrations.

(hydrological + CO2 + geochemical processes)

 HYDRUS + Wetland (CW2D/CWM1)(biogeochemical processes in constructed wetlands)

 HYDRUS + Fumigant(fate and transport of fumigants)

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Physical Nonequilibrium

Preferential Flow and Transport
Fractured Rock

Solute TransportpModelsMacroporous SoilŠimůnek and van Genuchten (2008):
a)

b)
Water

Heterogeneous
S di
Sedimentst

Solute



c)
Water

d)
Water
Immob. Mobile

SoluteSoluteMobileImmob. Mobile = im   mo

 = im   mo

Immob.

Water
Slow

SoluteSlow

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 = M  F

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Nonequilibrium Models

Chemical Nonequilibriumin the HYDRUS GUI

Solute TransportpModelsŠimůnek and van Genuchten (2008):

b)

c)

d)





s1 k



sk
c

sk

c

s2 k

c

sime

Variably-Saturated Water Flowe)Slow Fast

Immob. Mob.

se

im

mo

cim

cmo

smo

e

smok

sm e

sm k

Fast

a) Uniform Flowb) Mobile-Immobile Waterc) Dual-Porosity (Šimůnek et al.,al 2003)d) Dual-Permeability (Gerke and van Genuchten, 1993)

Th DualPerm
The
D lP
M d l
Module

a)

Fast

m

f

cm

cf

a) One-Site Kinetic Modelb)) Two-Site Model ((kinetic and instantaneous sorption)p)c) Two Kinetic Sites Model(particle transport, e.g., colloids, viruses, bacteria)d) Dual-Porosity
Dual Porosity with One Kinetic Site Modele) Dual-permeability with Two-Site Model

sf e

sfk

Solute Transport

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HYDRUS and its Modules

The DualPerm Module – An Application
Water flow and Solute Transport in
Dual-Permeability Variably-Saturated Porous Media HYDRUS + PHREEQC = HP1/2/3(hydrological + biogeochemical processes)

 HYDRUS + C-Ride(particle and particle-facilitatedparticle facilitated solute transport)

 HYDRUS + DualPerm(preferential water flow and solute transport)(pp ) HYDRUS + UNSATCHEM(hydrological + CO2 + geochemical processes)

 HYDRUS + Wetland (CW2D/CWM1)(biogeochemical processes in constructed wetlands)

Pressure head profiles for the matrix (left), isotropic fracture, and fracturewith KxA/KzA=10, and fracture with KxA/KzA=0.1 (right).

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 HYDRUS + Fumigant(fate and transport of fumigants)

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HYDRUS + UNSATCHEM
 HYDRUSHYDRUS--1D and HYDRUS (2D/3D)- Variably-Saturated Water Flow
- Solute Transport- Heat Transport- Root Water Uptake
 UNSATCHEM (Šimůnek et al.,al 1996)- Carbon Dioxide Transport and Production- Major Ion Chemistry- Cation Exchange- Precipitation-Dissolution (instantaneous and kinetic)- Aqueous Complexation

UNSATCHEM Module
1

Aqueousp
Components

7 Ca2+, Mg2+, Na+, K+, SO42-, Cl-, NO3-

2

Complexed
Species10

CaCO3o, CaHCO3+, CaSO4o, MgCO3o,
MgHCO3+, MgSO4o, NaCO3-, NaHCO3o,
NaSO4-, KSO4-

3

PrecipitatedSpecies6

CaCO3, CaSO42H2O, CaMg(CO3)2,
MgCO33H2O, Mg5(CO3)4(OH)24H2O,
Mg2Si3O7.5(OH)3H
3H2O
7 5(OH)

4

XCa, XMg, XNa, XK

4Sorbed Species

5

CO2-H2O Species

7

PCO2, H2CO3*, CO32-, HCO3-, H+, OH-, H2O

6

Silica Species

3

H4SiO4, H3SiO4-, H2SiO42-(exchangeable)

Kinetic reactions: calcite precipitation/dissolution, dolomite dissolution
Activity coefficients: extended Debye-Hückel equations, Pitzer expressions

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UNSATCHEM-2D Module

To evaluate the effectiveness of HYDRUS to predict: Water content and fluxes
 Concentration of individual cations (e.g., Ca2+, Mg2+)
 OverallO
ll salinity
li it (Electrical(El t i l conductivity
d ti it – EC)( Na )SAR 
 Sodium Adsorption Ratio (SAR)(Ca  Mg )2
 Exchangeable Sodium Percentage (ESP)


2

2

Na Conce
entration [meq/L]

UNSATCHEM - Lysimeter Study
50

Na+

30

10
0
0

-1

XCa2+

20

200

400

20

EC (dS m )Major Ion Chemistry Module

10 cm

40

600

800

1000

1200

1400

10 cm

15

I

10

R

I

R

I

R

I

400

600

800

1000

1200

1400

800

1000

1200

1400

5
0
0

200

0.5

10 cm

50 cm

-1 0.58
SAR (meq L )3-3

Water content (cmm cm )

10

0.4
0.3
0.2

6
4
2

0.1
0.0

0
0

200

400

600

800

1000

1200

1400

0

200

400

600

Gonçalves, M. C., J. Šimůnek, T. B. Ramos, J. C. Martins, M. J. Neves, and F. P. Pires, Multicomponent solute transport in soil
lysimeters irrigated with waters of different quality, Water Resources Research, 42, 17 pp., 2006.
Ramos, T. B., J. Šimůnek, M. C. Gonçalves, J. C. Martins, A. Prazeres, N. L. Castanheira, and L. S. Pereira, Field evaluation of amulticomponent solute transport model in soils irrigated with saline waters, J. of Hydrology, 407(1-4), 129-144, 2011.

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Šimůnek, J., and D. L. Suarez, Two-dimensional transport model for variably saturated porous
media with major ion chemistry, Water Resources Research, 30(4), 1115-1133, 1994.

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Wetland Module

HYDRUS and its Modules
 HYDRUS + PHREEQC = HP1/2/3(hydrological + biogeochemical processes)

 HYDRUS + C-Ride(particle and particle-facilitatedparticle facilitated solute transport)

 HYDRUS + DualPerm(preferential water flow and solute transport)(pp ) HYDRUS + UNSATCHEM(hydrological + CO2 + geochemical processes)

 HYDRUS + Wetland (CW2D/CWM1)(biogeochemical processes in constructed wetlands)

 HYDRUS + Fumigant(fate and transport of fumigants)

Constructed Wetlands (CWs) or wetland treatment systems

are systems designed to improve water quality
use the same p
processes that occur in natural wetlands but have the flexibilityyof being constructed effective in treating organic matter, nitrogen, phosphorus, and additionallyfor decreasing the concentrations of heavy metals, organic chemicals, andpathogenspgCW2D : aerobic and anoxic processes for organic matter, nitrogen andphosphorus (Langergraber and Šimůnek, 2005)
CWM1:: aerobic,
CWe ob c, anoxico c andd anaerobice ob c p
processes
ocesses foro oorganicg c matter,e,nitrogen and sulphur (Langergraber et al., 2005)
Subsurface Vertical (CW2D) and Horizontal (CWM1) flow constructedwetlands:

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Wetland Modules: Components

Wetland Modules: Processes

CW2D : aerobic and anoxic processes for organic matter, nitrogen and phosphorus
CWM1: aerobic, anoxic and anaerobic processes for organic matter, nitrogen and sulphur

Processes:

Components:

Heterotrophic Organisms XH

Langergraber, G., and J. Šimůnek, The Multi-component Reactive Transport Module CW2D for Constructed Wetlands for the
HYDRUS Software Package, Manual – Version 1.0, HYDRUS Software Series 2, Department of Environmental Sciences,
University of California Riverside, Riverside, CA, 72 pp., 2006.
Langergraber, G., D. Rousseau, J. Garcia, and J. Mean, CWM1 - A general model to describe biokinetic processes in subsurface
flow constructed wetlands, Water Science Technology, 59(9), 1687-1697, 2009.

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Nitrosomonas XANs

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HYDRUS and its Modules
 HYDRUS + PHREEQC = HP1/2/3(hydrological + biogeochemical processes)

 HYDRUS + C-Ride(particle and particle-facilitatedparticle facilitated solute transport)

 HYDRUS + DualPerm(preferential water flow and solute transport)(pp ) HYDRUS + UNSATCHEM(hydrological + CO2 + geochemical processes)

 HYDRUS + Wetland (CW2D/CWM1)(biogeochemical processes in constructed wetlands)

 HYDRUS + Fumigant(fate and transport of fumigants)

HYDRUS + Fumigant
 HYDRUSHYDRUS--1D and HYDRUS (2D/3D)- Variably-Saturated Water Flow
- Solute Transport- HeatH t Transport
Tt- Root Water Uptake
 Fumigant- Presence or absence of a Surface Tarp
- Temperature dependence of Tarp properties- Removal of Tarp at specified time
- Additional injection
jof fumigants
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Application of the Fumigant Module

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HYDRUS and its Future Modules?
 HYDRUS + Overland Flow(surface runoff and overland flow)

 HYDRUS + Freezing/Thawing, Meteo(atmosphere)…
(atmosphere)
 HYDRUS + Soil Mechanical Stresses(effects of hydrological processes on slope stability)
 HYDRUS + Global Optimization((genetic
ti algorithm,
l ith AMALGAMAMALGAM, DREAM
DREAM, …))
 HYDRUS + MODFLOW(h d l i l processes at a large(hydrologicallscale)l )Spurlock, F., J. Šimůnek, B. Johnson, and A. Tuli, Sensitivity analysis of vadose zone
fumigant transport and volatilization, Vadose Zone Journal, 12(2), 12 pp., 2013.

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HYDRUS Tutorials

OOver
3 thousand downloads in
i 2008,2008 over 5 thousand in
i 2009,2009
and about 10 thousand downloads in 2010 and 2011;
over 10 thousand registeredgmembers.
http://www.pc-progress.com/en/Default.aspx

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HYDRUS Web Site: References

Public Library of HYDRUS Projects

Over one thousand applications of HYDRUS
HYDRUS--1D and HYDRUS (2D/3D)
published in peerpeer-reviewed journal articles, and many more unpublished.

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Mathematical/Numerical Models

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Questions and Suggestions?

Mathematical Models have the potential to be powerful tools to help
understand and quantify the complexities of various processes in thesubsurface.
Mathematical Models are:
 a repository for currently available knowledge represent a practical tool to improve our understanding of andability to quantify various processes
g applications
ppof Mathematical Models include:
Meaningfulpredicting outcomes under given assumptions
testing hypotheses
identifying conditions and locations of increased risk
developing treatment strategies, andinforming management decisions







However it should be acknowledged that Mathematical Models are
However,
not expected to be precise predictors of reality, but are only as goodas their input parameters and modeling assumptions.

Thank
Th
k you ffor
your attention