SewerGEMS Model Performance and Run Time Issue

Farhan, here are a few things to supplement the article.

If the model is slow to open, it could be due to:

• Where the model is stored - if on a network location, it may be due to network bandwidth
• Large database size - check the size of the .STSW.SQLITE file. If it is excessively large for the size of the model, it could be due to the use of Change tracking as mentioned here.
• Large backgrounds - if the slow part is the refreshing of the background layers, check the attached files in the background layers manager. Make sure they are stored on your local hard drive for fastest performance with opening. If the model opens fast without the background, consider reducing the complexity of the file (cut-down version, reduced image resolution, etc), or using the AutoCAD, MicroStation or ArcGIS integrated platforms.
• Excessive output files - check the size of the other files in the same folder as the model with the same base file name. See this article.
• Speed of the computer - generally speaking better computer specifications will reduce the time taken to open a model. For example the speed of the CPU, amount of RAM, type of hard drive, etc.
• Some other problem - as a first troubleshooting step, try isolating a copy of the .STSW and .STSW.SQLITE files in a new folder on your local hard drive and try opening from there. Try opening one of the sample files located in the Samples subfolder within the SewerGEMS installation folder.

If the model takes a long time to compute, it could be due to:

• Complexity of the model - very large models will tend to take a long time to compute. Check your user notifications for indications of any data entry issues that should be resolved and try to keep the model input as simple as possible. Hydraulically challenging situations can cause the numerical solver to take an excessive number of trials to settle on a balanced solution.
• Run duration and timestep - check the simulation duration in the calculation options and confirm that the timestep is reasonable. For the Implicit solver, a typical timestep is on the order of 0.05 to 0.005 hours and for the SWMM solver, a typical Routing Step is on the order of 1-10 seconds.
• Numerical stability - if the solver has trouble converging, it can take significantly longer to run, and the results will often be unstable (the first indicator of that would be the continuity error in the calculation summary). The Explicit (SWMM)  See these articles for help:
  • Troubleshooting unstable SewerGEMS and CivilStorm results using the implicit solver
  • Troubleshooting unstable SewerGEMS and CivilStorm model results using the Explicit SWMM Solver
• Some other issues, possibly due to the speed at which your computer can write results/output files to your hard drive. As mentioned above, try a sample file to help narrow things down. If this does not help, please send a copy of the model for review per Yashodhan's post.

Hi Jesse/Joshi,

Thank you very much for your usual support. I have just sent the model again by following above instructions. I have uploaded it on the same day but no response received yet. Is there any urgent mode of communications options or online call/chat support Bentley is offering except this platform?

Thanks again

Hello Farhan,

When you securely upload the model data as per the instructions, a general practice is that you should confirm having uploaded the file(s) and provided us with the file(s) names in a reply to this post. It makes it easier for us to locate the model and get back to you.

Is this the model you shared: "00_Planning Model 120820 SRTM 30m Elevations"?

I will check it.

Hello Farhan,

When you securely upload the model data as per the instructions, a general practice is that you should confirm having uploaded the file(s) and provided us with the file(s) names in a reply to this post. It makes it easier for us to locate the model and get back to you.

Is this the model you shared: "00_Planning Model 120820 SRTM 30m Elevations"?

I will check it.

Hi Joshi,

Thank you very much for your response. Sorry I missed to inform you both the times. Yes, this is the model for your review regarding performance and recovery. Any other suggestions to improve it from your side will also be highly appreciated,

Thank you

Hi Jesse/Joshi/Larry/Scott,

I have again uploaded the SewerGEM model for a performance check. The model file size is continuously increasing and performance is drastically decreasing. I have tried the SQL Personal and able to see HMI (more than 11,000) but not succeeded in deleting the unnecessary files and improving the performance of the model yet. Can you please look at this and delete unnecessary files to reduce the size and improve performance. Your guidance to avoid future errors would also be very helpful.

The zip file name is "To Bentley for Performance Check_150820"

The main issue is the Model's performance however if possible please look at this error also as I am still getting this, the thread link is below for your reference, to avoid doubling please ignore the below thread regarding model uploading.

https://communities.bentley.com/products/hydraulics___hydrology/f/haestad-hydraulics-and-hydrology-forum/201702/wet-well-elevation-initial-error/603823#603823

Thank you very much

Hello Farhan,

I managed to delete the large number of entries in the Change Tracking Table (around 28 million records) which could be the reason for the slow model performance.

I tried opening and running the model on my side and didn't see any issues in opening the model and run time.

I have unchecked the "Track Changes" for now to stop tracking of changes. If possible upgrade to the latest version of SewerGEMS i.e. 10.03.01.08 where there is an option to archive tracked changes if the database grows too large due to multiple entries as happened in your case. Change tracking is useful of multiple people are working on a single model over a long period of time to understand what changes were made during the modeling time periods. See the below article which can guide you on this in future;

SQLITE database size grows very large due to Change Tracking

You can download the cleaned up model from the below link;

Download Link

The model database size is considerably reduced (order of 30 MB from earlier 3.8 GB)

As for the wet-well initial elevation issue I am seeing 532.5 m as the Elevation (Initial) at the "Exi Wet Well".

Hope this helps.