release.txt

                           SEAWAT-2000 Release Notes

     This file describes changes introduced into SEAWAT-2000 with each
official release; these changes may substantially affect users. In this file, 
packages and processes are referred to by their 3-or 4-character 
abbreviation.

NOTE: Any use of trade, product or firm names is for descriptive purposes 
      only and does not imply endorsement by the U.S. Government.



o Version 3.13.00 4/21/2006:

This version has been updated with MODFLOW Version 1.16.00.  In addition,
the ETS and DRT packages (including DTOB) have been modified to work with
the Variable-Density Flow (VDF) Process.



o Version 3.12.00 3/14/2006:

This version has been updated with MT3DMS 5.10, which includes a zero-order
growth/decay option through the reactions package.  The zero-order growth/
decay option can be used to simulate groundwater age.  This version also
contains modifications to the original MNW budget routine, which may not have
correctly written several variables to the cell-by-cell flow file.



o Version 3.11.02 9/23/2005:

This version contains a fix for a bug that may have caused transport time
step lengths to be too short for stress period 2 and greater.  This bug
would not have caused accuracy problems, but may have resulted in 
unnecessarily long computer runtimes for some simulations.



o Version 3.11.01 7/25/2005:

This version contains a fix for a bug that was introduced in 3.11.00 when 
MT3DMS Version 5.00 was incorporated into SEAWAT.  The size of the SS
array was increased in MT3DMS parts of the code, but not in the MODFLOW
parts of the code.  This caused freshwater boundary heads for RIV and GHB
boundaries to be calculated with a density of DENSEREF instead of a 
density value calculated with the concentration in the SSM package.  
The bug probably does not affect models of shallow aquifers but could
affect GHB fluxes for deep aquifer systems.



o Version 3.11.00 4/29/2005:

This version of SEAWAT-2000 contains MODFLOW-2000 Version 1.15.00 and MT3DMS
Version 5.00.  Thus, the new transport observation feature in MT3DMS is now
available for variable-density simulations.  The Multi-Node Well (MNW) 
package is now compatible with the Variable-Density Flow (VDF) Process; however, 
it is assumed that the well density is equal to the reference density 
(DENSEREF).  Thus, MNW wells should be restricted to freshwater parts of the 
model domain.

This version of the code contains a fix for a potentially serious bug in 
prior versions of SEAWAT-2000.  For some cases, the simulation would proceed
even if convergence had not been achieved with the flow solution.  In the current
version, SEAWAT will stop and write an error message to the output file and the
screen if flow convergence is not achieved.  Other bug fixes include 
(1) SEAWAT-2000 will no longer bomb of the number of columns exceeds 1000, and
(2) stability criteria for the transport equation are no longer enforced for 
constant concentration cells.



o Version 3.10.01 3/30/2004:

Following the convention for MODFLOW-2000 releases, this release is
designated as 3.10.01.  The ".01" indicates that this release contains
only bug fixes, rather than new packages or features.

This version contains bug fixes for three coding errors: (1) In the previous 
version, the value for HDRY was not always written to the output head file if 
a cell went dry during the simulation.  (2) A runtime error was encountered
in certain instances when the IMT Process was used with the GWF Process 
(instead of the VDF Process).  (3)  If MODFLOW timesteps were shorter
than the calculated transport timestep, the density array was not updated
properly.  To correct these errors, changes were made to swt2k.f and vdf1.f.



o Version 3.10 2/13/2004:

This is the first public release of the SEAWAT-2000 program, which is 
documented in OFR 03-426.

Since OFR 03-426 was printed and distributed, the FHB and HUF2 packages
have been incorporated into SEAWAT-2000.  There are no special instructions
for using the FHB package.  Presently, the Layer Variable-Direction Horizontal 
Anisotropy (LVDA) capability is not compatible with the VDF process.  The 
version of MODFLOW-2000 included in this release is Version 1.12.01.  The 
version of MT3DMS included in this release is Version 4.50.

With this release, there is one known bug: the Variable-Density Flow (VDF)
Process may not produce accurate results if quasi-three-dimensional layers
are included in the simulation.  Quasi-three-dimensional layers should not
be used with the VDF Process.