MODFLOW 6 timeseries slow simulation

[mvantil12]

I've recently begun utilising the MODFLOW 6 timeseries functionality, but I am experiencing very slow simulation runtimes. I have a transient simulation where recharge rates are uniform over the model domain but vary for each stress period. The simulation starts out quickly but gets slower as it progresses. I get the same results without using the timeseries functionality. Below is a sample of the .rch file I'm using. Thanks in advance for the assistance.

[langevin-usgs]

Are you using the latest version of MODFLOW 6? We've fixed some time series issues over the past several versions.

[mvantil12]

I was running with version 6.3.0. I tried running again using version 6.6.0 but had the same issue.

[langevin-usgs]

It's hard to say what's going on here without some more information. @mvantil12, I think we will need a copy of your model (with both the time series recharge package and the regular recharge package input files). We've run recent tests with our latest time series fixes and have seen good performance. @ScottBoyce, could you work on this as you have looked into time series performance in the past?

[ScottBoyce]

@mvantil12 would you be comfortable with sharing the model with me? I can try running it in the debugger to see what is slowing the model down. My work email is seboyce@usgs.gov

What we fixed a while ago was removing a check in the time series files that resulted in a slowdown for extremely long time series files or have millions of small ones, but yours might be caused from something else.

[mvantil12]

@ScottBoyce I've shared a OneDrive folder with the email above from my work email. I've included a MODFLOW 6 setup using the timeseries functionality for RCH, EVT and WEL packages, as well as another MODFLOW 6 setup using the regular versions of these packages. I've tested both RCH and EVT separately and both slow the simulation down when either one utilises the timeseries functionality.

I used Groundwater Vistas 8 to produce the datasets. The timeseries files and the changes to the RCH, EVT and WEL packages were made outside of Groundwater Vistas.

[ScottBoyce]

Thanks, I got your email and pulled your model. I will try and give it a grind and see what is going on.

[mvantil12]

@ScottBoyce Thanks Scott - appreciate the help.