From:                                         Simeon Herskovits [simeon@communityandenvironment.net]

Sent:                                           Tuesday, August 16, 2011 1:49 PM

To:                                               'Paul Taggart'

Cc:                                               Dana.Walsh@lvvwd.com; Susan Joseph-Taylor; Rick Felling; awaite@ccfirm.com; jeraldanderson@hotmail.com; 'gbenesch'; Needmoresheepco@yahoo.com; jevenden@fs.fed.us; johnbrhodes@yahoo.com; 'J. Mark Ward'; 'Paul EchoHawk'; rwsears@me.com; 'Laura Welcher'; scarlson@kcnvlaw.com; 'Aaron Contreras'

Subject:                                     RE: SNWA Cannot Reproduce Myers Predictive Model Runs

 

Paul:

 

As I mentioned when you called this morning, Tom Myers was out of town and unreachable from last Wednesday through Sunday.  He has reviewed the issues raised in your email, and has emailed me a written explanation and uploaded a set of files which together he believes should suffice to resolve any difficulty SNWA’s modelers are having. 

 

Tom’s written explanation is pasted beneath my signature block and confidentially notice below. 

 

The link to Tom’s uploaded files is:  https://rcpt.yousendit.com/1196009375/65145e7a41c53178433dc150225d5959. 

 

Per Tom’s description, the files uploaded are seven GW Vistas files and five supporting *.map files which will create the base maps used in Vistas, allowing one to see the geology, some of the wells, basins, etc., under the model grid. 

 

I am copying this response to the State Engineer’s staff and other protestants to ensure that they are informed concerning this latest exchange.  I have checked the link and it works quite easily to download the files.  We also are mailing copies of the same files on disk to all parties and the State Engineer.

 

Sincerely,

 

Simeon Herskovits

Advocates for Community and Environment

P.O. Box 1075

El Prado, New Mexico 87529

Phone:  575-758-7202

Fax:      575-758-7203

Email:   simeon@communityandenvironment.net

 

 

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Simeon,

SNWA’s difficulty with convergence reflects a minor problem in MODFLOW’s PCG2 solver.  Sometimes, the model will fluctuate around and within the convergence criteria without actually converging.  I’ve appended below a page from the GWVistas 5 manual where they mention this issue and state that the user should set a number of iterations after which to “force” convergence if the criteria are met. 

Second, Vistas allows the user to continue allowing the model to run even if convergence is not met after a set number of time steps (500 in these cases).  I allowed the model to do this and manually verified that the model actually is “at convergence” but just barely missing it.  I’ve attached a table below that shows all the time steps for which this occurred.  Note that head and residual criteria are 0.001 and 1.0, both of which are criteria that are so low compared to the head and flow changes that occur during solution as to be negligible.  My other option would have been to make the criteria larger – I find manually observing convergence to be a better option than to lower the criteria for the entire set of model runs.  Note that none of the runs are even remotely diverging from solution.

 

I used GWVistas Version 5.43 Build 7.  If SNWA uses the information above they should be able to replicate the model runs.  I don’t think that providing a different exe or dll file would make any difference.

 

I will send to you through yousendit.com another folder with the GWVistas files.

The files are in Nevada State Coordinates East in feet.  The coordinate transformation is given in the files but is: x offset = 941451.2, y offset = 27404432.6, rotation  = 3.9181 deg.  These are the coordinates of the lower left corner of the model grid; the rotation is an offset from due north-south.

 

Best,

Tom

 

 

Time Steps Not Quite Converging - Criteria

.001

1.0

Scenario

Stress Period

Time Step

Head

Residual

snwa91eq

3

63

2.04E-03

3.326

snwa60eq

all time steps converged

snwa30eq

3

159

-1.52E-03

-2.877

snwa91rec

3

99

6.94E-04

-1.164

snwa60rec

3

96

3.22E-04

1.061

snwa60rec

3

99

1.84E-03

-1.969

snwa30rec

all time steps converged

Definition of Time Steps

Period

Period Length (days)

No. Time Steps

Multiplier

Simulations with Recovery

1

27375

110

1.1

2

45625

60

1.1

3

219000

100

1.1

Simulations to Equilibrium

1

27375

110

1.1

2

45625

60

1.1

3

3650000

160

1.1

 

Snwa**eq – simulation pumping ** af/y to equilibrium

Snwa**rec – simulation pumping ** af/y with recovery

 

cid:image002.png@01CC5B33.A3259270

 

 

Tom Myers PhD

Hydrologic Consultant

Reno NV

775-530-1483

tom_myers@charter.net

 

 

 

 

 

From: Paul Taggart [mailto:Paul@legaltnt.com]
Sent: Wednesday, August 10, 2011 5:11 PM
To: Simeon Herskovits
Cc: Dana.Walsh@lvvwd.com; Susan Joseph-Taylor
Subject: SNWA Cannot Reproduce Myers Predictive Model Runs

 

Simeon

 

While SNWA has been able to reproduce the Steady-State model runs of Myers, we cannot reproduce the predictive runs.  Dr. Myers states in his report that there were slight convergence problems during simulation of the larger times steps in stress period three during recovery simulation.  However, we are having these convergence issues with all of the predictive runs and are therefore unable to reproduce his results.  We would like to rule out the versions of MODFLOW and/or Groundwater Vistas as the cause for the convergence problems we are seeing.  You will find below a list of what would help us to reproduce the results and we are hoping Dr. Myers can provide them.

We have run his data files using:

    USGS MODFLOW 2000 Version 1.18.01
    Groundwater Vistas Versions 4, 5, and 6 (with various sub-builds)

For GW Vistas, we have used the *.EXE and *.DLL versions of MODFLOW
2000.

From Tom Myers, we need:

    - The GW Vistas project files (*.gwv) and any supporting files.
    - A copy of the MODFLOW DLL/EXE Tom Myers is using to
      run the model.
      - If it is the USGS version, send it.
      - If it is a GW Vistas version, we are licensed to use versions
        4.x, 5.X, and 6.X.  Please contact Jim Rumbaugh at ESI if you
        have concerns about sending the EXE/DLL.  wwingle@newfields.com
        is the licensed user.

 

We need to resolve this ASAP as we need to be able to run the model to prepare rebuttal evidence, if any.  Please call me with any questions.

 

 

Paul G. Taggart

TAGGART & TAGGART, LTD.

108 N. Minnesota St.

Carson City, NV  89703

(775) 882-9900 - Telephone

(775) 883-9900 - Facsimile

 

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