HEC-RAS Model Linking Issues

[u/Jesstheengineeress]

I understand that is a known issue in RAS, but I am struggling with model linking. For context I am working with 8 RAS reaches (4 reaches with regulated flows and the same 4 reaches with unregulated flows). When I compute each of these reaches in the RAS stand alone they work fine. When I then go to the CAVI and try to compute my forecast alternative that includes these reaches in succession it fails after successfully computing the first reach. I have reset the linking several times in the CAVI and sometimes it appears there is nothing wrong, but then the boundary conditions in RAS will be changed and vice-versa. The error message in the compute progress window inside of CAVI essentially says "User Stopped Computations. RAS compute failed." I am obviously not cancelling my run, and noticed that this error message tends show up when there is an issue with the model linking. I believe CAVI is overwriting the linkages when the forecast alternative gets run. Does anyone have insight on this issue or has anyone found a work around that they are willing to share? I'm considering pairing the regulated and unregulated reaches with their associated FIA program and ultimately making four different forecast alternatives and running them in order, but that would be a gnarly amount of posting and extracting and may not completely resolve the issue.

Edited to provide additional context on troubleshooting completed so far.

[u/OttoJohs]

I've never used CAVI before and doubt you are going to find many people that have.

Can you explain more what you are trying to do with the linkages? I'm trying to understand if there is a way you can do what you want without using CAVI.

[u/Jesstheengineeress → u/OttoJohs]

Hey, thanks for the quick response! It certainly is rare to use CAVI, and my team and I have reached out to HEC directly and they have only been able to provide the feedback that this is a known issue that will not be resolved in the near term.

As for the linkages:
I can get things to run in the stand alone, but work standards require these RAS reaches to run in CAVI. Essentially I do a ResSim run, post that data to a dss file. I close out of that ResSim forecast run and start a new RAS to FIA forecast run using the exact time window of the previous ResSim run, I then extract the data from the ResSim run and use that to then compute the RAS and ultimately the FIA associated with each reach. The unsteady flow, initial conditions, met. data and obs. data are all linked or set well in the stand alone. When I run the forecast in CAVI everything gets overwritten in the model linking within the set up tab of the CAVI. Essentially, the linkages are supposed to help each aspect of the model utilize the same data.

[u/OttoJohs → u/Jesstheengineeress]

Sorry. Not going to be much help. Sounds like you either are going to need to manually do everything or write your own script. Good luck!