I have an issue with my Hydraulic Model.
I have analysed my model with two different approaches.
Used user-defined gutter-> Conventional-> Max Gutter depth 0
Used max gutter depth 0.06 m in this case(global edit in Catchbasin FlexTables)
Now the issue is, in second case it looks like the network is not capturing the full flow from the catchments. I checked the total flow from catchment contributing to a pipe and checked the flow in the pipe, they are not matching. In case 1 its matching.
I want to know if I had done a mistake. Please help me through this.
Case 1 Images:
Case 2 Images:
Check the capture efficiency of the catch basins in the second case. What is the inlet location you have set for the second case? Is the inlet "On Grade" or "In Sag"? If the inlet is "In Sag" it will capture 100% of the flow. However, it is also possible to have full capture with "On Grade" inlets. We would need to take a look at your model to see the results and identify if there is some data input problem.
Please share the model files (.stsw and .stsw.sqlite) for our testing. See the article below for details on sharing model files on the forum;
Sharing Hydraulic Model Files on the OpenFlows | Hydraulics & Hydrology Forum
Bentley Technical Support
I have uploaded the files for two cases. Please have a look
Hi Kartheek, thanks for providing the new, smaller model.
In the example case you highlighted with catchbasin P4-IN248-15, you are only comparing the peak flow values, which do not necessarily indicate loss of flow. As mentioned earlier, the introduction of the ponded area introduces attenuation (like a pond), flattening the peak but with the same volume. To see this, graph the catchment flow together with the catchbasin outflow:
For the example case you highlighted with Profile-1, that covers a different part of the network. If you graph hydraulic grade for one of the catchbasins such as P4-IN236-5 for example, you can see that the high HGL happens for brief periods of time due to what may instability (fine tuning of the calculation options may be necessary)
With that said, after discussing this with our development team, it was found that the combination of ponded area surface storage along with a catalog inlet, is not a valid combination and will lead to the unexpected overflow. You will need to select full capture in this case to see valid results for the in-sag inlet with ponded area. Note that in this case, if you have a gutter connected downstream, any overflow (from the subsurface network spilling out of the rim) will travel down the gutter. If you global edit the inlet type to catalog inlet in your smaller example model, you will no longer see overflow (lost to the system) and the high HGL you saw in that profile example will no longer occur.
Jesse DringoliTechnical Support Manager, OpenFlows ProductsBentley Communities Site AdministratorBentley Systems, Inc.
If I use full capture inlet instead of Catalog inlet spread value is not populated (Its showing N/A). But the spread value is to be shown in the model as it is client requirement. Is there a way to get spread values when using Full Capture inlets and used Defined gutter?
For an in-sag inlet, the spread is calculated based on the weir or orifice equation using the dimensions of a catalog inlet, to find the depth and spread necessary to "push" all of the incoming approach flow into the opening. When the inlet type is set to full capture, this information is not available so the depth and spread are not calculated.
I will be discussing this further with our development team as I see that the SWMM solver has a requirement of using a surface storage method with an in-sag inlet. (yet this will cause overflow as mentioned). We'll get back to you as soon as possible.
Note that if you use the Implicit solver instead of the SWMM solver, you can use a catalog inlet in-sag without a surface storage method selected, and any overflow will go down the downstream gutter.
Hi Kartheek - just a quick update here. I am working with our developers on a potential fix to CivilStorm that will enable you to see accurate results when using catalog inlets in-sag, both with and without downstream gutters. I will keep you updated on progress.
Thanks Jesse Dringoli, will be eagerly waiting for the update
The catchbasins you are using are all in-sag without any gutters. Can you confirm that you intend to keep them this way and not add any gutters? Are the ponded areas above these inlets all indeed in-sag, where flooding would never have the chance to pass down a gutter?
After further investigation it was found that the unexpected overflow (lost from the system, when using catalog inlets in-sag with ponded surface area) is due to the "Maximum Gutter Depth" property. Flooding depth above this will cause overflow. If you want to assume that all overflow will remain in the ponded surface storage (and potentially later recede), set the maximum gutter depth property to a large value such as 10 meters.
Here are the calculation option adjustments that worked well for me to achieve stable results in the "Phase 4C" model that you had provided. This is in addition to setting all the catchbasin max gutter depth fields to a large value:
Routing Step: 1 secondOutput Increment: 0.05 hoursUse Bentley Transition Equation: True
With this, overflow (lost to the system) does not occur, and the results appear to be stable (at least from a few spot checks, in addition to noticing a low continuity error). Note that the flooding depth does still get a bit high at the flooded nodes, but this may be expected due to the surface storage size and the extent of the flooding.
We cant propose 10 m gutter depth as this will give huge spread value which is not actual. I have changed the gutter depth to 0.1m which is maximum curb height.
I have also changed the Routing Step to 1 second and Use Bentley Transition Equation to True.
This change helped with Profiles a bit but there is no change in overflow losses.
We are intended to keep the Catch basins in the same way.(When I tried to change the inlet to On Grade, Civilstorm is crashing. I think its not accepting on grade inlets for Catalog Inlets)
Just to remind you. Our main intention is to show the spread value in the model. This is not possible using user-defined full capture inlets. So we opted Catalog inlets(same dimensions) which led to Overflow losses and Max HGL issues.
Kartheek, the overflow is caused by the flooding depth exceeding the max gutter depth property. In other words, it assumes that when the max gutter depth is overtopped, the excess water becomes overflow. Your model exhibits excessive flooding causing relatively high flooding depths.
In the real system, what happens when the water level exceeds 0.1 m?