Water Resources Applications Software

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Summary of MOCDENSE

       mocdense - A two-constituent solute transport model for ground water
                  having variable density

       This model simulates solute transport in flowing ground water.  It
       is applicable to two-dimensional, cross-sectional problems involving
       ground water with constant or variable density.  The model computes
       changes in concentration over time caused by the processes  of
       advective transport, hydrodynamic dispersion, mixing or dilution
       from fluid sources.  The concentrations of two independent solutes
       can be modeled simultaneously.  Temperature is assumed to be
       constant, but fluid density and viscosity are assumed to be a linear
       function of the first specified solute.  If a second solute is
       specified, it is assumed to be of a trace amount such that it does
       not affect the fluid density or viscosity.  The aquifer may be
       heterogeneous and anisotropic.  The model has been used mostly in
       studies of either saltwater intrusion or dense contaminant plumes.
       The model was documented by Sanford and Konikow (1985).  For a
       documentation of the numerical method used, see the report by
       Konikow and Bredehoeft (1978).

       The model couples the ground-water flow equation with the solute-
       transport equation.  The digital computer program uses an iterative
       strongly-implicit procedure to solve a finite-difference
       approximation to the ground-water flow equation.  The model uses the
       method of characteristics to solve the solute-transport equation.
       This incorporates a particle-tracking procedure to represent
       advective transport and a two-step explicit finite-difference
       procedure to solve equations that describe the effects of
       hydrodynamic dispersion and fluid sources.  This explicit procedure
       has several stability criteria associated with it, but the
       consequent time-step limitations are automatically determined by the

       Version 3.2 1995/01 - Most current version.  This version includes
          several upgrades and fixes to minor bugs from earlier versions.

       Version 1.0 1985 - Original version released.

       Initial conditions, boundary conditions, aquifer properties at every
       node, grid descriptors, and linear equation parameters that relate
       fluid density and viscosity to solute concentration.

       See documentation.

       MOCDENSE is written in Fortran 77 with the following extensions:
       use of integer*2 declarations and use of the $ format descriptor.
       Generally, the program is easily installed on most computer systems.
       The code has been used on UNIX-based computers and DOS-based 386 or
       greater computers having a math coprocessor and 4 mb of memory.

       Sanford, W.E., and Konikow, L.F., 1985, A two-constituent solute
          transport model for ground water having variable density: U.S.
          Geological Survey Water-Resources Investigations Report 85-4279,
          89 p.

       Konikow, L.F., and Bredehoeft, J.D., 1978, Computer model of two-
          dimensional solute transport and dispersion in ground water: U.S.
          Geological Survey Techniques of Water-Resources Investigations,
          book 7, chap. C2, 90 p.

       One-day introduction during the class Modeling Transport of Ground-
       Water Solutes (GW2080TC), offered annually at the USGS National
       Training Center.

       Operation and Distribution:
          U.S. Geological Survey
          Hydrologic Analysis Software Support Program
          437 National Center
          Reston, VA 20192

       Official versions of U.S. Geological Survey water-resources analysis
       software are available for electronic retrieval via the World Wide
       Web (WWW) at:


       and via anonymous File Transfer Protocol (FTP) from:

         (path: /pub/software).

       The WWW page and anonymous FTP directory from which the MOCDENSE
       software can be retrieved are, respectively:


       See for
       information on ordering printed copies of USGS publications.

       moc(1) - Two-dimensional method-of-characteristics ground-water
                flow and transport model
       modflow(1) - Modular three-dimensional ground-water flow
       Modflowp(1) - Parameter-estimation version of the modular model
       sutra(1) - Saturated and (or) unsaturated, constant or
                  variable-density fluid flow, and solute or energy
                  transport (2-dimensional finite-element code)
       vs2di(1) - A graphical software package for simulating fluid flow
                  and solute or energy transport in variably saturated
                  porous media

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