[Luis Partida]

Here you go

[Luis Partida]

I saw this question posed on reddit some time back and I think the user just deleted the BC line saved, closed re-poened and just drew it again and the error no longer popped up

[Luis Partida]

I will say this about this issue, while HEC intends to do away with the Geometry Data Editor, it is still by far the most stable environment to make model updates. I recommend not using RAS Mapper for mods like you explained.

[Luis Partida]

What version of RAS are you in. I am currently in V6.3.1 but maybe you are right, the model I am using uses constant and loss so i see many more variables. I wonder if SCS CN method you have to use computation outputs to view excess precip and compare it with your input and that would be your losses.

[Luis Partida]

In RAS Mapper, right-click on your results plan and select “create a new results layer” then expand “additional 2D variables” this is where loss method outputs reside, hope this helps!

[Luis Partida]

I believe it is stated in RAS documentation that calculated WSE values as low as 0.01 are considered negligeable. That being said, if a target calibration of 0.05 cfs is desired, I would imagine RAS not being sensitive to roughness coefficients. Instead, what I would try is increasing or decreasing the # of XS’s in the model because the averaging between XS data will alter results but to the hundredth of a decimal place…I am not sure. Good luck

[Luis Partida]

I had a discussion with some colleagues regarding cupping specifically. Basically, that document was written prior to the release of HEC-RAS V6.2 which introduced a new render mode called Depth Weighted faces or “precip mode”. This render mode eliminates most issues related to cupping, so I would try this before any GIS related external mapping efforts.

[Luis Partida]

I would make a virtual clone of the terrain you have. Then recheck the elevations at the problem structures and I would even add a new modification on top of that modification. The next thing I would do is the basic dumb RAS debugs like save and close and reopen, disassociate that geometry with said terrain, save close reopen, rename the terrain save close and reopen, change the culvert invert to allow the model to work run it for a short duration and then go back and adjust back save close reopen…I know this isnt much help but we all know RAS is buggy as hell sometimes

[Luis Partida]

HEC intends to do away with the geometry data editor in the future and solely use RAS Mapper for everything, but, until that day comes, the Geometry Data Editor will always be more stable. That being said, I wouldnt focus on this that much.

[Luis Partida]

I am not sure why such a small grid size is needed and as a general rule of thumb, RAS models should try to stay under 1 million cells. There is not a limit documented but you might want to check where you are writing too and if you have enough disk space to handle it. Worst case scenario you handle the operation in ArcMap/Pro

[Luis Partida]

No, dont do multiple meshes for each basin as the interconnectivity of them all would not only be a build, but a computational nightmare. Model it as a single subbasin in 1 mesh. In Harris County i believe for their modeling updates, placed hydrographs approximately 20-30% north of the subbasin outlet to not double account for time of concentration. BUT that rule worked well because delineation guidelines required subbasins around the 1-5 sq mile size. These methods were widely tested and documented in a series of white papers.

My suggestion is you go back to delineations and delineate to smaller areas giving you multiple hydrograph output locations then you can go back into a RAS domain, import your subbasin file as a map layer and then place your hydrographs as such.

[Luis Partida]

Hey Scott, this is truly a great read and was well written by HEC to help best understand bridges in 2D modeling and what RAS is doing behind the scenes. I would give this a read.

https://www.hec.usace.army.mil/confluence/rasdocs/r2dum/latest/development-of-a-2d-or-combined-1d-2d-model/modeling-bridges-inside-2d-flow-areas

[Luis Partida]

Hi Scott, so the company that I am currently at also has the VM option which most of our numerical modelers use. I would say that the only “problem” with this is that similar to link you posted, is that processor speed is paramount. VM’s and cloud computing are capped at like 2.65 ghz and thats pretty bad even if we can have hundreds of cores available. In my personal experience I had a dell with 32 cores and a processor that turbo’d up to i think 5 ghz and it was SO fast with RAS computations

[Luis Partida]

Hey Chris, have you also considered building the reservoir in the terrain with a terrain modification? You then could potentially use SA connecters within a single mesh to enter the breach rules surrounding the elevated reservoir…just thinking out loud

[Luis Partida]

No you cant carve out like that. You could do two 2D areas and connect them with SA connectors.

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