Readme.txt

   SRV 1983-2006 Model Update Information File - Version 3.0  03/25/2014
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The updated 1983-2006 SRV Groundwater Flow Model contains several improvements
over perviously released models.  General model improvements and other suggestions
to model users are detailed below.  The model input and output files are
provided in separate folders.  

Model Improvements:

  In this update the model cell size has been decreased to 0.5 by 0.5 mile and
  the model grid has been expanded to include the entire Phoenix AMA.  The 
  resulting model grid has 125 rows, 222 columns, and 27,750 cells.  

  Part of the Lake Pleasant sub-basin has been added to the active model area.  

  The model calibration has been extended 4 years to include 1983 through 2006.

  New model layer geometry has been developed for this model based on well
  logs from the recent past and thoes used in previous model studies.  The
  new log data has helped reduce model uncertanity in areas where well data
  was defiecient in past model releases.

Notes to Modelers :

* The model was developed using ArcMap and version 3 was run in DOS using
  MODFLOW-2005, Version 1.10.

* Two solvers, the GMG and PCG, are included in the model input folder.  Model
  results are virtually identical when using either of the solvers.  The only
  major difference between the two solvers is that the PCG will solve in about
  half the time of the GMG solver.

* Several issues with the stream Routing package have been reported by users 
  attempting to import the Version 1 model into Groundwater Vistas.  We have
  worked with Jim Rumbaugh to identify and fix these issues.  The latest stream
  package (srv_strm_v3d.str)will import and run in Groundwater Vistas. To properly
  run the SRV 1983-2006 - Version 3 within GW Vistas, the user needs to be using
  GW Vistas Version 5.33, Build 14 or newer.

* The layer hydraulic conductivity (K) distributions in the Version 1 model have
  been adjusted to more accurately honor values from previous model releases.
  The reasons and methods used in redistributing the K vlues are discussed in 
  detail in the model technical report.

* An improved Head Observation (HOB) package has been developed and added
  to this version.  The new package give slightly different statistical results
  than the version included in the initial model release.

* A modified recharge package (SRV8306F1.RCH) has been added to this version.
  The new recharge package redistributes the volume of Ag recharge for the years
  2003-2006 to more accurately reflect the distribution of Irrigation Grandfathered
  Rights (IGFRs) in the model domain.


A technical report is available that describes in more detail the model development,
calibration, and results.  The report is available on the Department's website or 
by contacting the Arizona Department of Water Resources modeling unit.

The modeling units email address is (modeling@azwater.gov).

  



