What is it?
The Multiple Species Transport tool is built using MT3D-USGS, a modular three-dimensional (3-D) transport model produced by the U.S. Geological Survey (Bedekar and others 2016). MT3D-USGS and its predecessors (MT3DMS, RT3D, and MT3D) are widely used to simulate advection, dispersion, and chemical reactions of contaminants in groundwater. IGW-NET provides the user with the option to use MT3D-USGS to postprocess groundwater flow models and solve contaminant fate and transport equations resulting from discretization of the conceptual model.Parameter lookup tables may be helpful for users familiar with MT3D/RT3D variable names.
How to use it?
A) For Realtime Modeling:
1) After building your groundwater model, apply the MT3D transport solver (Conceptual Model Tools>DomainAttr>Simulation Settings>Solver Options>MT3D)
2) Open the multiple Species Model Options tool (Conceptual Model Tools>DomainAttr>Simulation Settings>Other Settings>multiple Species Model Options)
3) Choose the types of reactions to be modeled and Build/Edit
Processes:
- Linear sorption (simple retardation factor/partitioning)
- First-order sorption (concentration dependent)
- Dual-domain mass transfer (mobile and immobile porosity)
Chemical Reactions: (no species interactions except chain)
- First-order rate reactions (concentration dependent decay/production coef.)
- Zero-order reactions (simple concentration independent decay/production)
- Monod kinetic reactions (kinetic biodegradation with specified half saturation constant and biomass)
- First-order chain reactions (sequential parent-daughter decay of user defined species)
Reaction Models: (MT3D-USGS species interactions and RT3D-like templates)
- BTEX Instant Aerobic Decay (equivalent to RT3D module 1)
- BTEX Kinetic Decay using Multiple EAs (equivalent to RT3D module 3)
- PCE Sequential Decay (equivalent to RT3D module 6)
- PCE/TCE Decay (aerobic/anaerobic) (equivalent to RT3D module 7 without Cl)
- Single Pair Instant EA/ED (User defined species)
More options (additional options to allow user to specify different properties for liquid and solid phases)
4) Ensure at least one species is defined in the "Multiple Species" window, and set any model wide parameters.
5) Apply point/line/zone sources or properties for the defined species (e.g., draw a zone or open zone attributes, click the "Biochemical" tab, check "multiple Species" and "Edit multiple Species Property"...)
6) Simulate the model (Simulation Tools>SIMULATE)
7) View analysis charts to display multiple species plots (Analysis Tools>Analysis>Display Charts)
B) For Post Analysis:
1) Start by Simulating a IGW-NET Groundwater model.
Models must:
- Have at least one plume defined
- Use the MT3D transport solver (Conceptual Model Tools>DomainAttr>Simulation Settings>Solver Options>MT3D)
- Define all spatial geometry needed for multiple species model (zones, lines, wells, etc)
2) Load groundwater model into the Multispecies tool by hitting Apply or using Last Multiple Species Model
For transient groundwater flow models, the flow field from the last step executed is used.
3) Choose the types of reactions to be modeled and Build/Edit
Processes:
- Linear sorption (simple retardation factor/partitioning)
- First-order sorption (concentration dependent)
- Dual-domain mass transfer (mobile and immobile porosity)
Chemical Reactions: (no species interactions except chain)
- First-order rate reactions (concentration dependent decay/production coef.)
- Zero-order reactions (simple concentration independent decay/production)
- Monod kinetic reactions (kinetic biodegradation with specified half saturation constant and biomass)
- First-order chain reactions (sequential parent-daughter decay of user defined species)
Reaction Models: (MT3D-USGS species interactions and RT3D-like templates)
- BTEX Instant Aerobic Decay (equivalent to RT3D module 1)
- BTEX Kinetic Decay using Multiple EAs (equivalent to RT3D module 3)
- PCE Sequential Decay (equivalent to RT3D module 6)
- PCE/TCE Decay (aerobic/anaerobic) (equivalent to RT3D module 7 without Cl)
- Single Pair Instant EA/ED (User defined species)
More options (additional options to allow user to specify different properties for liquid and solid phases)
4) Run Simulation
Set simulation length and timestep (limit 300 steps)
Select display and draw options while model is running
5) View Results
View model results
Plot model cross sections
Plot model breakthrough curves
Tool Logfile
Internal errors from the tool may be checked by inspecting the tool log file. This can be found on the side bar:Analysis Tools > Analysis > View Run-time Msg > Select Msg File 'mgnMT3D Run-time Log File'
Supported/Unsupported Features
IGW-NET supports:RT3D Module Equivalents
- BTEX Instant Aerobic Decay (RT3D module 1)
- BTEX Kinetic Decay using Multiple EAs (RT3D module 3)
- PCE Sequential Decay (RT3D module 6)
- PCE/TCE Decay (aerobic/anaerobic) (RT3D module 7 without Cl)
Groundwater Flow
- IGW-NET and MODFLOW flow solvers
- MODFLOW-like boundary condition packages:
- Recharge (RCH)
- Well (WEL)
- Drain (DRN)
- General Head Boundary(GHB)
- River (RIV)
IGW-NET does not yet support:
RT3D Module Equivalents
- BTEX Instant Decay using Multiple EAs (RT3D module 2 cannot be implemented in MT3D-USGS)
- Rate Limited Sorption (RT3D module 4 overlaps with a dual domain model)
- Double Monod (RT3D module 5 cannot be implemented in MT3D-USGS)
- User defined reaction modules with multiple EA/ED reactions.
Groundwater Flow
- Lake (LAK)
- Stream Flow (SFR)
External Links
- MT3D-USGSLanding page for MT3D-USGS
MT3D-USGS manual - Bedekar and others (2016)
MT3D-USGS Input Information - USGS (2019)
FloPy documentation.
- RT3D
Landing page for RT3D
RT3D manual - Clement (1997)
- MT3DMS (version 5.2 utilized implicitly when running variable density models with SEAWAT)
Documentation landing page - University of Alabama Hydrogeology Group
MT3DMS user manual - Zheng & Wang (1999)
MT3DMS v5 supplemental documentation - Zheng (2010)