Friday, March 28, 2008

On-Line MODFLOW Guide

With all the versions of MODFLOW coming from the USGS these days, it is hard to keep up with incompatibilities & quirks. This is especially true when using Groundwater Vistas because we support almost all flavors of MODFLOW and most of the new packages and processes. The USGS has an on-line guide that is pretty useful. It has all of the users manuals for the various versions and packages and there is also a stand-alone guide you can put on your computer. It even has a chart of package compatibility. For example, the new UZF (Unsaturated Zone Flow) Package only works with MODFLOW2005 and the GMG (Geometric Multigrid Solver) Package does not work in MODFLOW96. It really pays to read the manuals for each package you are using, especially the really new ones like SFR, HUF, ETS, DRT, etc. Here is the link to the MODFLOW Guide:

Tuesday, March 25, 2008

Better Matrix to Zone Conversion

I had to convert a bunch of models from GMS to Vistas this week. As many of you know, when you import a model into Vistas, the various properties like hydraulic conductivity are set up as matrices. That means you just get a bunch of numbers instead of a zone database. If you just want to run the model and make minor revisions, this is fine. However, if you want to recalibrate the model or use some other tools in Vistas, you may want that matrix of numbers simplified to a zone database. The only way to do that was to use Props/Options and turn off the use of matrices. Then you had to wait, often many hours, for the conversion to happen.

I set out to make this process more efficient and have reduced the conversion time by many orders of magnitude. So if you get the Version 5.16 Build 9 update, converting properties from matrix to zone is very quick. You also get to choose the number of significant digits used to determine whether two real numbers are equal. This can help simplify a complex matrix.

You may also notice that we skipped from build 6 to build 9 in the most recent blog postings. The intervening builds were just testing new system code schemes.

Tuesday, March 18, 2008

Recent GV Modifications

Here are some enhancements and bug fixes for GV Version 5.16 Builds 2 through 6:

- We continue to work on the Pest Null Space Monte Carlo procedures. We hope to have this finished by the time our Advanced Seminar takes place in May.

- We added a new customized telescopic mesh refinement procedure for the Southwest Florida Water Management District. It is called Mine TMR and was designed to analyze the impacts from shallow phosphate mines in Florida. You'll see it under the Grid/Export menu. If you work in Florida and want to use it, contact Robert Peterson at SWFWMD.

- If you used the transient copy for recharge and you had the option selected to save recharge concentrations for all components, only component 1 concentration actually got copied.

- When you run PEST, GV creates a batch file called pestgv.bat that actually runs the model and all necessary pre- and post-processors. If you are using MODFLOW-SURFACT Version 3, depending on the date you purchased it, it might not work with the command line GV writes in the pestgv.bat file. This has been fixed.

- When importing SFR input files under BCs/Import/MODFLOW Package, the SFR unit number got set to zero.

- If the CHD head was equal to the layer bottom, GV was not catching the problem and MODFLOW would quit running with a dry constant head error.

- GV now writes a validation.log file to the gwv5 directory. This is for diagnosing problems with security codes. It is analogous to the hardlock.log file that helps diagnose dongle problems.

MODFLOW Conference

Just a reminder that the MODFLOW conference will be held at Colorado School of Mines in Golden, Colorado on May 18 to 21. If you have not attended before, it is well worth the trip. Good papers, nice people, great scenery, decent beer. Plus we'll be giving out handy little (1 gigabyte) usb flash drives at our booth. This is the only conference I attend so this is your chance to get inside info and twist my arm for new features!