GROUND WATER -- Update of solute-transport model

                        GEOLOGICAL SURVEY
                        RESTON VIRGINIA  22092

                                                  Code 4351 5016

                                                  June 5, 1979


SUBJECT:  GROUND WATER -- Update of solute-transport model

The attached "update note" documents a number of revisions that
have been made recently to the two-dimensional solute-transport
model that is documented in Techniques of Water-Resources
Investigations, Book 7, Chapter C2.  The modified program will
generally yield more accurate results, and it is recommended that
all users of this model modify their source code accordingly.

As detailed in the note, instituting the changes in the program
will require the deletion of 146 original statements and the
insertion of 179 new statements.  A punched deck consisting of
these 179 new cards will be routed or mailed to you on request to
the Ground Water Branch.

The load module (program K590) in SYS1.LOADLIB on the IBM System
was updated on May 17, 1979, to include all of these
modifications.  On the Reston MULTICS, the new source code is
available in segment moc2.fortran and the new object code in
segment moc2 of directory >udd>Transport>LKonikow.

Also, the program uses an iterative ADI procedure to solve the
ground-water flow equation.  For certain problems this method is
unsatisfactory.  In such cases, the strongly implicit procedure
(SIP) should work well.  Richard Healy in the Illinois District
Office has adapted a SIP code to substitute for the documented ADI
code.  Arrangements to receive a copy of the code for the SIP
subroutine can also be made through the Ground Water Branch.

If there are any problems or suggestions concerning the use or
documentation of this solute-transport model, please contact
Leonard F. Konikow (FTS 928-6904).

                                     (s) Gerald Meyer
                                     Chief, Ground Water Branch


WRD Distribution: A, B, S, FO