HEC-RAS 2D hidden shallow water

[Arnaud Monserat]

Hello all,
I am currently working on a river model. Since the downstream part of it goes through floodplains, i’ve tried to model it with a 1D/2D coupling. Most of it works but when i plot the rresults in the RAS-Mapper, I get some strange results. My main concern is that shallow water seem to not be mapped in the final result.
When I use the default slop option for map rendering, it shows some ponds with no connections to the overflowing river, but my simulation tells me water is definetly overflowing here.
I did a second try with another render with the option to render the shallow water with the horizontal rendering method. And there i get some confirmation that thoses cells are really wet, but it just doesn’t show with the slopping method.
I’ve tried to turn the plot tolerance to ridiculously small depths. I also tried the full momentum method for computations but it did not seem to solve this problem specifically but i can’t seem to make it work
HEC-RAS version is 6.2, and time step for simulation is 1 second

PS : i can’t seem to add screenshot, i want to add some to better explain my problem so if there’s any tip i will also take it !

Thanks in advance for your help and tips

[Luis Partida]

I think i understand your problem here. One thing to note is RAS Mapper is just a visual tool at the moment with new capabilities continuing to be added one as the software progresses. That being said, if a WSEL is calculated in a 1D element like a storage area, and that WSEL is lower than the terrain elevation, then no depth will be mapped in RAS Mapper however the 1D results will show data there. So basically if the terrain will not allow it to be mapped then that may be your “issue” with visualization.

[Arnaud Monserat]

Hi,
Maybe this is the problem in some part of my model, but I tried checking in detail the terrain layer in some places to gauge the error and the WSEL was above.

[Author]

Posts