MT3DMS UPGRADE
INFORMATION
Department
of Geological Sciences
202 Bevill Building
Version History
5.20: October
2006
5.10:
October 2005
5.00:
February 2005
4.50:
May 2003
4.00:
August 2001
3.50.B: August 2000
3.50.A: November
1999
3.00.B: May 1999
3.00.A: June 1998,
initial release
Release [3.00.A] June 1998
Initial release.
Release [3.00.B] May 1999
Bug
Fixes:
1. Fix an ‘array out of bound’ error
in subroutine MIC of the GCG package.
This error has no effect if the array bound-checking option of the Fortran compiler is not turned on.
2. Fix a problem related to the
assignment of initial concentrations for the sorbed/immobile phase in the RCT
package. When the nonequilibrium
sorption is simulated, by default the initial concentrations for the sorbed
phase are assumed to be in equilibrium with those for the dissolved phase. When the dual-domain mass transfer is simulated,
by default the initial concentrations for the immobile phase are assumed to be
zero. The user has the option to
override the default values by specifying their own values in the RCT input
file. However, because of a bug in the
previous version, the default values are always used regardless of user input.
3. Fix a potential minor problem in
determining the transport stepsize required for the
explicit solution of the dual-domain mass transfer reaction.
Enhancements:
1. Reorganize the main program
slightly to facilitate the addition of multispecies reaction packages into
MT3DMS.
Bug
Fixes:
1. Fix a problem which may lead to
inaccurate solutions when first-order irreversible reaction (radioactive decay
or biodegradation) is used in conjunction with nonequilibrium sorption or
dual-domain mass transfer.
2. Fix a potential floating point
overflow error in determining the maximum transport stepsize
required for explicit solution of the dispersion term.
Enhancements:
1. Add a new option for simulating
dual-domain mass transfer in the presence of linear sorption (refer to the
User's Manual, revised November 1999).
This option is implemented as ISOTHM=6 in the reaction (RCT) package,
and replaces the original dual-domain mass transfer option ISOTHM=5. While ISOTHM=5 is kept in the program for
compatibility considerations, ISOTHM=5 is equivalent to ISOTHM=6 with the first
sorption constant SP1 (Kd)
set to zero.
2. Add a new option for specifying
fluid sources directly through a mass-loading rate [QC] (M/T) instead of a
concentration [C] (M/L^3) for the source flux (refer to the User's Manual,
revised November 1999). This option
allows the user to specify a source for the transport model without first
specifying a flow rate [Q] in the flow model.
3. Improve the program structure for
keeping track of global mass budgets and reporting mass balance information,
particularly for transport simulation in dual-domain systems or under transient
flow conditions.
4. Improve the performance of the
Generalized Conjugate-Gradient (GCG) matrix solver.
Bug
Fixes:
1. Fix a problem related to the
first-order kinetic reaction. In Version
3.50.A, when the first-order kinetic reaction is simulated (IREACT=1) but no sorption
(or dual-domain mass transfer) is included in the simulation (ISOTHM=0), the
concentration change due to the reaction is not properly updated if the user
chooses the explicit solution scheme, i.e., the GCG solver package is not
turned on. This bug only occurs with
Version 3.50.A, and has no effect if the user turns on the GCG solver package,
or if the sorption or mass transfer is simulated along with the kinetic
reaction.
2. Fix a potential problem related to
the mass-loading point source (ITYPE=15) implemented since Version 3.50.A. The problem causes more mass to be added than
the specified mass loading rate after the first stress period. This bug only occurs when the flow model is
steady state but the transport model has multiple stress periods to accommodate
the changes in the mass loading rate.
Other
Modifications:
1. Modify the use of the “minimum
saturated thickness [THKMIN]” option.
The THKMIN option is used to turn off (made inactive) those cells in the
unconfined model layers where the saturated thickness is negligible relative to
the total thickness of the cell (DZ).
The purpose for using this option to avoid the situation in which a cell
with a negligible saturated thickness severely restricts the transport step
size for the entire model. When the
saturated thickness is above the specified minimum in a new flow time step, the
cell that has been turned off is re-activated (made active). In this version, the THKMIN option is not
used by default. In other words, if the
user does not specify any value for THKMIN, it is equivalent to setting
THKMIN=0, i.e., the cell is turned off only if the hydraulic head at the cell
is below or equal to the bottom elevation of the cell. The user can specify any value between 0 and
0.05 for THKMIN, i.e., when the saturated thickness at any cell is below 0 to
5% of the total cell thickness (DZ), the cell would be made inactive. If the user specifies a value greater than
0.05 (5%), the user-specified value is reset to the default value of 0.01 (1%).
2. Modify the method for assigning the
non-default concentration of point sources (wells, rivers, etc.) in simulations
with multiple stress periods. In
previous versions, the concentration of a point source, once specified for a
particular stress period, will stay the same for the remaining stress
periods. Therefore, to turn off a
user-specified point source in a subsequent stress period, it is necessary to
re-define the source in the input file with its concentration set to zero. In this version, the concentration of any
source specified for a stress period is only valid for that stress period
alone. In a simulation with multiple
stress periods, the user can either choose the ‘REUSE’ option to reuse all
point source information from a previous stress period, or specify all the
point sources for each stress period.
Note that an exception to the above general rule is the hand
Bug
Fixes and Other Modifications:
1. Fix
problems related to the third-order TVD solver (subroutine CFACE in the source
file of the Advection Package). In
previous versions, the TVD solver may become unstable or result in large
negative concentration values, particularly when applied to field-scale
problems with irregular model geometries.
In the current version, the performance of the TVD solver is improved by
making adjustments near the inactive cells and by implementing a more robust
form of the flux limiter.
Enhancements:
1. Support MODFLOW-2000 through a new
version of the Link-MT3DMS Package (LMT6).
Information on the LMT6 Package for MODFLOW-2000 is provided in the U.S.
Geological Survey Open-File Report 01-82 by Zheng, Hill and Hsieh (2001), available
at http://water.usgs.gov/software/ground_water.html.
2. Add support for additional MODFLOW
sink/source packages. The MODFLOW
sink/source packages supported by the previous versions of MT3DMS (prior to
4.00) include Well (WEL), Drain (DRN), Recharge (RCH), Evapotranspiration
(EVT), River (RIV), General-Head-Dependent Boundary (GHB), and Time-Varying
Constant-Head Boundary (CHD). In
addition, the Streamflow-Routing Package (STR) can be supported through the River option if the two
are not used in the flow simulation simultaneously. MT3DMS 4.0 supports two new packages, the
Reservoir (RES) and Specified Flow and Head Boundary (FHB). Furthermore, it allows the simultaneous use
of the RIV and STR Packages in the flow simulation. Finally, MT3DMS 4.0 includes new options
which make it simple and easy to support more MODFLOW sink/source packages in
the future.
3. Add a new method to start a MT3DMS
simulation through a name file that is similar to the name file used by
MODFLOW-2000. The name file contains the
names of most input and output files used in a model simulation and controls
the parts of the model program that are active.
In addition, it is possible to override the default names assigned to
several MT3DMS optional output files (e.g., MT3D001.UCN, MT3D001.OBS, and
MT3D001.MAS) through the name file. For
more information on the MT3DMS name file, see Zheng, Hill and Hsieh (2001) and
the file ‘readme.txt’ included with the MT3DMS 4.0 distribution files.
Bug
Fixes and Other Modifications:
1. Fix
a problem related to the ‘reuse’ option in the Sink/Source Mixing (SSM) Package. If a
model includes a certain number of point sources with user-specified concentrations,
the cell locations, source types and concentration values must be specified in
the SSM Package input file for the first stress
period. For subsequent stress periods,
the number of point sources with specified concentrations can be set to -1 to
reuse the point source information entered for the first stress period. A problem in Version 4.00 may cause the
option to function incorrectly under certain circumstances.
2. Fix
a problem in the array reader RARRAY which can lead
to incorrect input of an external binary file such as the unformatted
concentration (UCN) file saved from a previous run
and used as the initial concentrations for a restart run. This problem occurs only when the unformatted
files used by MT3DMS are defined as unstructured true-binary files
(FORM=’binary’ or ACCESS=’transparent’).
For standard unformatted files (FORM=’unformatted’ and
ACCESS=’sequential’), the array reader RARRAY
functions properly.
3. Fix
a problem in the General-Conjugate-Gradient (GCG)
Package which can cause the GCG solver to fail to converge when a 1D model is oriented along a column (y axis)
or vertically (z axis). This problem
does not occur if the 1D model is oriented along a row (x axis).
4. Fix
a problem related to printing of simulation results at user-specified
times. This problem can cause MT3DMS to
skip printing the simulation results at one or more user-specified times under
some rare circumstances.
5. Allow
the transport options (packages) to be activated through the MT3DMS NameFile without changing the relevant input file record (TRNOP) in the BTN Package input
file. This is consistent with the NameFile method of opening files as used in MODFLOW-96 and
MODFLOW-2000. The input record TRNOP in the BTN Package input
file no longer has any effect if the NameFile method
is used to open the input/output files for MT3DMS.
Enhancements:
1. Add
an option to save the sorbed-phase or immobile-liquid-phase concentrations in
unformatted concentration (UCN) files if sorption or
dual-domain mass transfer is included in the simulation. The file is named by default as MT3DnnnS.UCN,
where nnn indicates the species index number. (The default names can be overridden through
the MT3DMS NameFile.)
If sorption is simulated but not dual-domain mass transfer, the
sorbed-phase concentration is saved. If
dual-domain mass transfer is simulated (either without or with sorption), the
immobile-liquid-phase concentration is saved instead. The unit for the sorbed-phase concentration
is expressed in terms of sorbed mass per unit mass of bulk soil matrix. The unit for the immobile-liquid-phase
concentration is expressed in terms of mass per unit volume of fluid. The structure of sorbed-phase or
immobile-liquid-phase UCN files is identical to that
of dissolved-phase UCN files so that the former can
be processed in the same manner as the latter.
Major
Changes:
1. The name-file procedure is now the
only method to start a MT3DMS simulation run.
A name-file specifies the names of most input and output files used in a
model simulation. In addition, it
controls the parts of the model program that are active, i.e., the “packages”
that are used in the current simulation.
As a result, the “TRNOP” array in the BTN input file is no longer used. However a dummy input
line must still remain where the “TRNOP” is formerly
specified.
2. The optional implicit matrix
solver, the General Conjugate-Gradient (GCG) solver,
must now be used in every simulation. In
other words, the dispersion, sink/source and reaction terms are now always
solved by the implicit finite-difference method, regardless of whether the
advection term is solved by the implicit finite-difference method, the mixed
Eulerian-Lagrangian methods, or the third-order TVD method.
3. A single finite-difference cell may
now contain multiple sinks/sources of the same type, for example, multiple
wells. If this is the case, it is
necessary to assign the source concentrations individually if all of them act
as sources of specified concentrations.
Enhancements:
1. Add
a new Transport Observation (TOB) Package as
documented in Zheng (2005) to save the calculated concentration at any model
cell and the calculated mass flux at any sink/source location. The calculated values are saved to output
files, and optionally, along with the statistics of residuals between the
calculated and observed values at the observation locations. The calculated concentrations can be
interpolated from the nodal values if the observation point does not coincide
with a model node. The calculated mass
flux can be defined over any arbitrary group of sink/source cells referred to
as a mass flux object.
2. Support
the Multi-Node Well (MNW) Package (Halford and Hanson, 2002) used by MODFLOW-2000 to simulate
the flow to a well screened over multiple nodes (layers). The MNW Package
automatically partitions the total flow prescribed for a MNW
into individual nodes (layers) and determines a single head value in the
wellbore. Accordingly, MT3DMS v5
computes a single composite concentration for the same wellbore based on the
flux-weighted concentrations of the injected fluid (if any) and the flow rates
from different layers.
3. Add
support for additional MODFLOW sink/source packages, including Drain with
Return Flow (DRT) and Evapotranspiration
with a Segmented Function (ETS), both documented in
Banta (2000). The DRT package simulates the reinjection of a portion of the outflow from a drain cell
back into the aquifer. MT3DMS assigns the concentration at the outflow cell as
that of the reinjected source at the return
drain-flow location. The ETS package is supported in
a manner similar to the original EVT package.
Bugs
Fixes and Other Modifications:
1. Fix a bug with the mass loading
option (ISSTYPE=15) in the Sink/Source Mixing (SSM) Package. This
bug was introduced in version 5.00 and might cause some mass loading source to
be skipped. The bug occurs only when the
particle-based solution techniques (MOC/MMOC/HMOC)
are used.
2. Improve the hand
3. Fix a bug in the Link-MT3DMS (LMT6)
Package that is distributed with MODFLOW-2000 v1.15.01 (
Enhancements:
1. Add
an option to simulate zeroth-order decay or
production as documented in Zheng (2005).
The standard MT3DMS code prior to version 5.10 includes only the
first-order kinetic reactions in the Chemical Reaction (RCT)
Package. However, zeroth-order reactions
may be useful for describing certain types of biogeochemical decay or
production. In addition, zeroth-order
reactions can be used for direct simulation of groundwater ages or calculation
of parameter sensitivities.
Bugs Fixes and Other Modifications:
1. Fix a bug in the TOB Package which may affect the mass flux object calculation for recharge and evapotranspiration.
2. Fix a potential problem in the BTN Package which may lead to abnormal program termination when the fully implicit finite-difference scheme is used with the transport stepsize multiplier set to greater than 1.0 and when the simulation requires a very large number of transport steps.
Enhancements:
1. Add an option to include three-dimensional multicomponent diffusion coefficients in the transport simulation as documented in Zheng (2006). The standard MT3DMS code prior to version 5.20 only allows the input of a single uniform diffusion coefficient per model layer and the same diffusion coefficient for all solute components.
2. Add an option to simulate the effect of a recirculation well whose input concentration is equal to the output concentration at an extraction well. See Zheng (2006) for more information.