Webinar: MODFLOW Solvers, Speed, Convergence and Robustness

MODFLOW continues to be the groundwater flow model of choice for hydrogeologic investigations, remedial evaluations, and water resource management throughout the world. In recent years, MODFLOW has advanced to include greater simulation capabilities and sophisticated numerical techniques for enhancing convergence and robustness. Recent releases of MODFLOW-NWT, MODFLOW-USG and MODFLOW 6 by the USGS, and of USG-Transport by GSI Environmental include state-of-the-art solution schemes to handle extremely complex and difficult models.

Difficulties in convergence or slow simulations are caused by various conditions specific to each model. Steady-state or transient simulations of the same model may also have different optimal settings for robustness and efficiency. Therefore, the solution schemes available in MODFLOW-NWT, MODFLOW-USG, MODFLOW 6, and USG-Transport include tuning parameters to assist with robust and efficient simulations for each situation. Default or suggested settings often work but may not be optimal: a 2- to 10-times speed-up may be obtained in many situations by examining simulation behavior and adjusting the solver parameters appropriately.

This webinar has been developed for modelers who want to get more out of their MODFLOW model. The course covers principles on which the advanced solvers are based; the available tuning parameters and how they work; and how to analyze solver behavior to select optimal solver settings for any simulation. Specific topics that will be covered include:

  • Beyond “WET/DRY” tricks – up to MODFLOW 6
o   Formulation and Discretization
o   Nonlinear Solution Schemes and Linearization
o   Linear Matrix Solution

  • Model and Solver Parameter Settings
  • Runtime Diagnostic Tools
  • Troubleshooting, speed and convergence strategies
This 2 hour webinar is developed and conducted by Dr. Sorab Panday who has decades of experience with these advanced modeling solution schemes. It includes materials you probably will not find in a book or learn in school. The webinar is right for you if you have encountered one of the following:

  • Sought help from modelers at the USGS, the support desk at your favorite MODFLOW GUI developer, or from Sorab Panday at GSI Environmental on convergence or speed issues for your groundwater flow model
  • Wished that your MODFLOW model would run faster – it probably can if you knew how
  • Hoped that randomly changing one of the solver parameters will fix your convergence issues – a focused and targeted strategy would work better
  • Screamed at your computer screen in frustration expecting that would fix the model
  • Want to get more educated on nonlinear and linear solution schemes in general
  • Desire to be the Mighty Mouse of modelers