Overview

MT3D99 – an enhanced version of MT3DMS, that includes support for implicit solver, TVD Solution scheme, dual-porosity advection-diffusion, Non-equilibrium Sorption and Monod Kinetics, and Multispecies Reactions, including First-Order Parent-Daughter chain reactions, and Instantaneous Reactions among species. The model program is based on a modular structure to permit simulation of transport processes independently or jointly.

MT3D99 is linked to the USGS's three-dimensional groundwater model MODFLOW and can be easily applied using a graphical pre-and post processor like Visual MODFLOW.

MT3D99 is an ideal tool for simulating groundwater plume migration in either two or three-dimensional groundwater flow systems.

Product Details

Input Features

The MT3D99 model input is compatible with standard MODFLOW data files, including three- dimensional transient flow fields with the presence of wells, drains, rivers, recharge, evapotranspiration and a variety of boundary conditions.

The model retrieves the heads and various flow and sink/source terms saved by the model and automatically incorporates the specified boundary conditions.

Analysis Features

MT3D99's modular structure is similar to MODFLOW and allows simulation of sink/source mixing, chemical reactions, advection and dispersion independently without reserving computer memory space for unused options.

Solution options include:

• Implicit solution scheme
• TVD solution scheme
• Method of characteristics (MOC) solution scheme
• Modified method of characteristics (MMOC) solution scheme
• Hybrid method of characteristics (HMOC) solution scheme

Spatial discretization capabilities and mass transport boundary conditions:

• Confined, unconfined and variably confined/unconfined aquifer layers Inclined model layers and variable cell thicknesses within the same layer
• Specified concentrations or mass flux boundaries
• Solute transport effects of external sources and sinks

Chemical reactions included are:

• Equilibrium based linear or non-linear sorption Non-equilibrium sorption
• First-order irreversible decay or biodegradation
• Zero-order and mixed-order
• Monod kinetics

Dual Porosity

The dual porosity advection-diffusion mass transfer model provides a more effective approach than the standard single-porosity advection-dispersion model for simulating solute transport in fractured media or extremely heterogeneous porous media.

Nonequilibrium

The nonequilibrium sorption model enables the user to examine the role of sorption in solute transport and remediation processes without the restrictive local-equilibrium assumption.

Complete Mass Budgets

MT3D99 computes and saves cell-by-cell mass budgets enabling the user to compile a detailed mass budget for any sub-region of the model grid.

Multi-Species Reactions

MT3D99 includes an enhanced reaction package to handle BIOPLUME-type aerobic and anaerobic reactions between hydrocarbon contaminant and any user-specified electron acceptors, and parent-daughter chain reactions for organic or inorganic copounds. This enables MT3D99 to analyze natural attenuation and bioremediation without using a third-party add-on reaction package.

Automatic Restart Option

MT3D99 supports a new automatic restart option to greatly facilitate the continuation run from a previous simulation.

Output Features

A post-processing program is also included with the MT3D99 package to assist in the plotting of concentration breakthrough curves and contour maps using Surfer or other plotting packages.

However, in order to best visualize the results of MT3D, it is recommended that you utilize a graphical pre-processing and post-processing software package like Visual MODFLOW.

Additional Details

Download our Software and Instrumentation catalog (PDF)