Hello,
I'm simulating a open channel network in sewergems using Implicit solver. In certain stretches, it shows the HGL is above the ground level and I was in the intention that it is flooding. Following is a sample figure.
But the post in the below link confused me.
https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/17596/what-happens-when-the-water-level-exceeds-the-top-elevation-of-an-open-channel
How can we find out whether the channel get flooded, isn't it , if HGL is above the GL of the channel segment? Is overflowing and flooding are two different conditions?
Regards
Nishadi
Hello Nishadi,
If a channel is overtopping it will will be evident in the profile at certain time steps. You can scroll out to a time step where the hydraulic grade is above the ground elevation. As noted in the link, there will likely be overtopping being reported in the user notifications.
Overtopping and flooding are essentially the same thing in this case. The cross section defines the dimensions of the channel. If the cross section is overtopping, that would mean that the channel is also overtopping.
There is a much higher hydraulic grade reported at one point in your screenshot. You may want to review some of the troubleshooting steps for the implicit solver for this.
Regards,
Scott
Answer Verified By: Nishadi
A distinction to be made is flooding vs. overflowing. As the article explains, the side walls of a channel are extended up so that flow is not lost (no overflow), but the program will still warn you that the channel is overtopped/flooded, so that you are aware that the channel's capacity has been exceeded and you may need to address the problem so that the actual channel in the real system does not overflow.
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Dear Scott and Jesse,
Thanks for the replies. It's clear now.
BR