Aquaveo & Water Resources Engineering News

Better MODFLOW observation plots

GMS has included observation tools for a long time. These work with any numerical model and let you compare field observed data with model computed output. With transient data, the time of the observations doesn't necessarily match the model output times. In this case GMS would do a temporal interpolation to come up with a model calculated value.

When MODFLOW 2000 came out it included built in observations calculated when you ran MODFLOW. Now if the observation time didn't match the output time it didn't matter because MODFLOW would be sure to calculate an additional output at the observation time.

The residual errors calculated by MODFLOW have been available in GMS since shortly after MODFLOW started computing them but the GMS observation plots still behaved the old way, by doing a temporal interpolation. Until now. We just replaced the old way with the new and revamped several observation plots. The following images illustrate the difference.

Old and busted. Notice the interpolation times of the upper and lower range don't always match the observation times.
New hotness. Upper and lower bands replaced with fixed point-in-time box symbols. The color makes it easier to interpret.


GMS 8 has an interface to the USGS SEAWAT model. SEAWAT is a combination of MODFLOW and MT3D that allows for the simulation of density dependent flow and transport. I have included an animation of one of the sample problems from the SEAWAT documentation. We also have created a tutorial that shows how to use the SEAWAT interface within GMS.

GMS Community Edition

Starting at GMS 8.0 there is a free version of GMS called "GMS Community Edition". This version includes the MODFLOW and 3D Grid components and thus allows grid-based creation and editing of MODFLOW simulations. Existing simulations can be imported and edited as normal. There are size limits in this free version: grids can be no bigger than 5,000 cells and MODFLOW is limited to 3 stress periods. You can still import models bigger than this but then printing and saving are disabled. Otherwise, printing and saving work as normal. Also, once a model exceeds the limits a watermark will appear in the graphics window.

We hope this free version will allow more users to easily begin discovering GMS.

March 2011 Sprint Highlights

Some of the more interesting accomplishments from the March 2011 sprint:
  • Released GMS 8.0 with lots of new features including a free Community Edition, support for MODFLOW 2005 and SEAWAT, faster and better looking graphics, improved contouring, ArcGIS map server layers, and much more.
  • Updated the GMS web pages at The graphics are better, the content and layout is much easier on the eyes, there's a new learning center with videos and tutorials, and a new editions and pricing page, and a new "Why MODFLOW with GMS?" page.
  • Posted a new video on our YouTube channel showing the MODFLOW stream package and streams in a conceptual model.
  • Fixed 33 bugs
  • Found and fixed some memory leaks
  • Finished the new lighting options that will be included in version 8.1
  • Made good progress on implementing the new Rasters that will be available in 8.2 and will handle DEM data much better.
  • Added a bunch of pages to the wiki about the SEAWAT interface.
  • Made good progress on improving the annotations that are new in 8.0 and will work much better in 8.1
  • Added more automated testing of the 64 bit version of GMS that will be available with 8.1