Transient model calibration in MODFLOW-NWT under Modelmuse GUI

[Mehreteab Yohannes]

I am simulating groundwater flow using MODFLOW-NWT under Modeluse GUI.I have two layers (unconfined upper layer and confined layer).  I have finished the calibration of the steady-state. I am facing a problem in transient calibration

In steady-state calibration the aim is to match the observed and simulated head by altering the horizontal and vertical hydraulic conductivity and can be easily checked on HOB package (RMSE value and residual errors). I am using Specific yield (SY), Specific storage (SS), HK and VK to calibrate transient model calibration. Would you please tell me:

1. How can I calibrate transient model

2. Where do I visualize the result of calibration (like HOB in steady-state)

3. How do I know whether my model is calibrated or not

[Nadège Vanden Berghe]

through Data/Data visualisation and the Head Observation Results section you can import your HOB file and make it plot by ModelMuse. I particulary appreciate the fact that ModelMuse represents error with blue and red circles, colored and sized differently depending on sign and importance of discrepancy. In transient mode, I think you should use groundwater chart which is a little software able to extract heads change from model simulation at particular cell coordinates.

To calibrate your model you should obviously adapt your K until you have an equaly distribution of red and blue circles with acceptable ranges of error. However you can try ModelMate in order to perform automatic calibration of your problem. My experience is that this is seldom necessary and perform your own diagnostic and understanding on way to calibrate your model is more valuable as well as efficient. ModelMate procedure is also more complicate than a straigh-forward adaptation of K values.

[Alfonso Flaquer]

Hi Mehreteab,

Could you find a solution to visualize the result of calibration in transient simulation? 

I´m having the same problem.

[An Ho Antonio Taylor]

For non-stationary calibration, it is critical to define the initial heads to start running the model, which are done by extracting the heads from the final stress period of the stationary state, or by running the model in a pre-development steady state, And then run it forward, the times of the observations must correspond to the temporal discretization that it configures, and after selecting the hydraulic parameters to be calibrated paying attention to the limits of those variables in UCODE, Mr. Saul Montoya has a very good video tutorials About this procedure in spanish The page is called http://gidahatari.com/ih-es/ also Mr. Richard Winston has a very helpful video tutorials about this topic.

A number of performance measures have been proposed in the past to indicate when a model fits historical measurements  "well enough" to be acceptable for use in predictions.
These include RMS, SRMS, MSR and SMSR. It has been suggested that performance measures, for example, SRMS < 5%, should be agreed prior to a modelling study and  that these should be included in acceptance criteria. However, experience has shown that it is not always desirable to specify a target value of some performance measure. this process is very time consuming and frustrating, keep in mind and good luck!

i have a attached some info about the calibration insights.

Best Regards!

 
     
 

--
You received this message because you are subscribed to the Google Groups "MODFLOW Users Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to modflow+unsubscribe@googlegroups.com.
To post to this group, send email to mod...@googlegroups.com.
Visit this group at https://groups.google.com/group/modflow.
For more options, visit https://groups.google.com/d/optout.

[Sophia Wolfenden]

Dear Mehreteab,

Congratulations on finishing your initial calibration!

To calibrate your transient simulation, you will need similar information to your steady-state model--specifically data through time such as transient water levels, hydraulic conductivity values, surface water flux estimates, etc. These will need to be incorporated into your model to estimate its effectiveness for simulating whatever scenario(s) you are trying to model.

To visualize your results, you have a few options. The first is to estimate your parameters using statistical information, such as the range in residuals over the range in measurements, the root mean squared error of your data, and the absolute mean residuals. I tend to also look at observed vs. simulated plots both through time and all together (such as residuals through time), as well as hydrographs for all transient water level locations. For guidance on these methods I recommend looking at Mary Hill and Claire Tiedeman's book "Effective Groundwater Model Calibration: With Analysis of Data, Sensitivities, Predictions, and Uncertainty", which covers everything you would need to know. They also address all of the questions you listed. If this isn't available, the USGS also has posted guidelines for assisting with the calibration process. Finally, I think the ASCE also has some standards, though they are pretty vague. Good luck!

Cheers,
Sophia

P.S. You can calibrate Hydraulic conductivity values in the transient simulation as well. Just make sure that your properties ultimately match between your steady-state and transient models.

[Alfonso Flaquer]

Thanks for the advice and the documentation.

I was able to see the calibration curves through ModelMate and GW_chart.

Thanks!

--
You received this message because you are subscribed to a topic in the Google Groups "MODFLOW Users Group" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/modflow/GPIPrpbkvVY/unsubscribe.
To unsubscribe from this group and all its topics, send an email to modflow+unsubscribe@googlegroups.com.

To post to this group, send email to mod...@googlegroups.com.
Visit this group at https://groups.google.com/group/modflow.
For more options, visit https://groups.google.com/d/optout.

--

AfLa