Documentation for the MODFLOW 6 Groundwater Transport Model

First posted March 3, 2022 For additional information, contact: Director, Integrated Modeling and Prediction DivisionWater Mission AreaU.S. Geological Survey12201 Sunrise Valley Dr., MS 411Reston, VA 20192-0002Contact Pubs Warehouse This report documents a new Groundwater Transport (GWT) Model for MODFLOW 6. The GWT simulates three-dimensional transport of single chemical species in fowing groundwater based on generalized control-volume fnite-difference approach. Although each is only able to represent species, multiple Models may be invoked within 6 simulation solute non-interacting species. designed work with the Flow (GWF) 6, which transient, fow. version model documented here must use same spatial discretization used by GWF Model; however, that can represented regular grids consisting layers, rows, columns, or more general unstructured grids. (1) advective transport, (2) combined hydrodynamic dispersion processes velocity-dependent mechanical molecular diffusion, (3) adsorption absorption (collectively referred as sorption) solutes aquifer matrix, (4) transfer between mobile domain one immobile domains, (5) frst-or zero-order decay production, (6) mixing from sources sinks, (7) direct addition mass. also through advanced package features, such streams, lakes, multi-aquifer wells, unsaturated zone. If application uses Water Mover (MVR) Package connect fow packages, then these packages represented. described this have been implemented fully implicit manner are solved system equations using iterative numerical methods. present does not an option calculate steady-state solutions; if solution required, transient evolution time steps until no further changes concentrations detected.