U.S. Geological Survey (USGS)                     modflow-lgr(1)

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NAME
     modflow-lgr - MODFLOW with Local Grid Refinement

ABSTRACT

     MODFLOW is a three-dimensional finite-difference ground-
     water model that was first published in 1984.  It has a modular
     structure that allows it to be easily modified to adapt the
     code for a particular application.  Many new capabilities have
     been added to the original model.  Mehl and Hill (2005) document
     an enhancement to MODFLOW, which is called Local Grid Refinement
     (LGR).  The combined code is called MODFLOW-LGR.  MODFLOW-LGR
     allows a small part of a larger model domain to be refined
     without refining the entire model.


HISTORY

      MODFLOW-LGR Version 1.1 08/8/2007 - Added support for multiple
         non-overlapping child grids.

      MODFLOW-LGR Version 1.0 03/01/2006 - Initial release.


DATA REQUIREMENTS
     In order to use the LGR capability in MODFLOW-LGR, two model
     datasets are required.  The first dataset defines the larger
     model domain, and the second defines the smaller part to be
     refined.


SYSTEM REQUIREMENTS

     MODFLOW-LGR is written primarily in Fortran 90. Only the GMG
     solver package is written in C.  The code has been used on
     UNIX-based computers and personal computers running various
     forms of the Microsoft Windows operating system.


DOCUMENTATION

  The basic documentation for MODFLOW-2005 (on which LGR is based) is
  contained in:

Harbaugh, A.W., 2005, MODFLOW-2005, the U.S. Geological Survey modular
ground-water model -- the Ground-Water Flow Process: U.S. Geological Survey
Techniques and Methods 6-A16, variously p.

  The addition of LGR to MODFLOW-2005 is documented in:

Mehl, S.W. and Hill, M.C., 2005, MODFLOW-2005, the U.S. Geological Survey modular
ground-water model -- documentation of shared node local grid refinement (LGR)
and the Boundary Flow and Head (BFH) Package: U.S. Geological Survey Techniques
and Methods 6-A12, 68 p.

Mehl, S.W. and Hill, M.C., 2007, MODFLOW-2005, the U.S. Geological Survey modular
ground-water model -- documentation of the multiple-refined-areas capability of
local grid refinement (LGR) and the Boundary Flow and Head (BFH) Package: U.S.
Geological Survey Techniques and Methods 6-A21


CONTACT
    U.S. Geological Survey
    Office of Ground Water
    411 National Center
    Reston, VA 20192

    http://water.usgs.gov/ogw/