Splitting the simulation in two or more…

[brubolonhez]

Good Morning, everyone!
I`m trying to simulate a river, but I would like your opinion… My model is unstable and, to get a better result, I thought about splitting one of my channels in two. That way, it was a lot easier to control the variables. The idea was to import the DSS data of the last dowstream element of the firs part as the start of my next simulation… The question is, what would be better: to use the stage or flow hydrograph as the boundary condition? They are resulting in differents solutions, specially in the XSs closer to breaking point….

Here is how I broke the channel in two…

Thank you all for your opinions!

[Anonymous]

Thats absolutely ok to do! in many cases it is necessary to begin the stabilization of large river networks and i always recommend stabilizing 1 reach before moving to the next. Your downstream boundary condition is not as important to the stabilization as you may think when breaking up a multiple stream network. You can use normal depth or a known WSEL just make sure that your model does not go into critical depth within the last cross section.

Then use the hydrograph output as the input at your US cross section in the connecting model.

[brubolonhez]

I see! Thank you for your reply, Luis!
If its not to much to ask, do I need to simulate them together again, after I got them stable?
I was doing exactly was you proposed, but my idea was to export the end results of each simulation with Hec-GeoRAS and then create a unique flood map. My concerns were brought up when i saw the differents stages results for the XS on the breaking point, since than I would not be able to join the maps or, at least, wouldn’t know witch stage to use at that XS!

Again, thank you for your help!

[Anonymous]

Using HEC-RAS 5.0.5 you wont need HEC Geo-RAS. That software is now no longer needed for anything as RAS mapper within HEC-RAS does everything and does it easier.

Yes everytime you split a model that is in fact one river, do your best to combine them after they are all stabilized. There still will be some issues but for the most part you will have solved the most tedious portions of stability

[brubolonhez]

Ok, than. Thank you for all the help!!

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