MT3D-USGS: Groundwater Solute Transport Simulator for MODFLOW

Release Date:

MT3D-USGS capabilities and features include:

  • unsaturated-zone transport;
  • transport within streams and lakes, including solute exchange with connected groundwater;
  • capability to route solute through dry cells that may occur in the Newton-Raphson formulation of MODFLOW (that is, MODFLOW-NWT);
  • new chemical reaction package options that include the ability to simulate interspecies reactions and parent-daughter chain reactions;
  • new pump-and-treat recirculation package that enables the simulation of dynamic recirculation with or without treatment for combinations of wells that are represented in the flow model, mimicking the above-ground treatment of extracted water;
  • reformulation of the treatment of transient mass storage that improves conservation of mass and yields solutions for better agreement with analytical benchmarks;
  • separate specification of the partitioning coefficient (Kd) within mobile and immobile domains;
  • capability to assign prescribed concentrations to the top-most active layer;
  • change in mass storage owing to the change in water volume now appears as its own budget item in the global mass balance summary;
  • ability to ignore cross-dispersion terms;
  • definition of Hydrocarbon Spill-Source Package (HSS) mass loading zones using regular and irregular polygons, in addition to the currently supported circular zones; and
  • ability to specify an absolute minimum thickness rather than the default percent minimum thickness in dry-cell circumstances.