[Toby]

Try using lateral structures which link the ends of the cross sections. Use a tailwater connection type of Cross Sections of a river reach. Have the cross sections end in one reach where the cross section from the other reach starts. Or if you can go 2D.

[Toby]

Have you imported / created a land cover map in ras mapper? The 2d polygon can only be used with a land cover map that is already imported. It overwrites the base values.

Check page 3-21 of the HEC RAS 2D users manual.

[Toby]

Check out the free plugin to QGIS, RiverGIS. http://rivergis.com/ras2d_geometry.html It might do the trick for you.

[Toby]

Hi Cameron,

I was using the 2D equations, with 10 1d/2d iterations.

From now on I will not use split cells across lateral structures!

cheers,

Toby

[Toby]

Hi Jake,

I have been trying to work with velocity data in the HDF files inside Program R. I think the issue for the ARC process is that the HDF data is not in a raster format. Even though much of your mesh could be in a structured grid, there will be some irregular points in your mesh. I have tried bringing in the xy (face points) data and the velocity data then interpolate between the irregular data to a raster surface.

#R code
xVel <- h5read("plan.p01.hdf", "Results/Unsteady/Output/Output Blocks/Base Output/Unsteady Time Series/2D Flow Areas/YOUR MESH NAME/Node X Vel") #I transpose the xy data FacePointXY <- t(h5read("plan.p01.hdf", "Geometry/2D Flow Areas/YOUR MESH NAME/FacePoints Coordinate") Take a look at the data with the HDF Viewer and you can pull out xy data and velocity data and save it as a csv if that helps get it to a shapefile and interpolate to a raster.

[Toby]

I recently had this problem too, but was able to correct it with the brealkine enforcement tool. Is your breakline cell spacing different than the mesh? Maybe try and change the cell spacing (maybe larger?) and see if it works.

[Toby]

You most likely need to interpolate between your points before going to raster.

Try creating a TIN first then a raster. In Arc this is easy to do, create a shapefile from your xyz data, build a TIN or Terrain Geodatabase, and then convert the TIN or Terrain to raster.

You can also go open source with cloud compare. http://www.danielgm.net/cc/

One of many ways to do it in CC.
http://www.danielgm.net/cc/forum/viewtopic.php?t=1514

[Toby]

“This type of boundary condition should only be placed in areas where the flow and stage
are highly one‐dimensional in nature.” HEC-RAS 1d/2d manual pg. 63

Maybe try and put the 1d/2d connection at station 464. Your flow is expanding as the slope changes and as the floodplain widens. Appears as if the flow may not be highly one-dimensional where you go from 1d to 2d. Another idea is to add more cells at the interface, but try to keep cells gradual as you change their size.

Does Manning’s from the 1d section match the 2d area?

[Toby]

Just a thought….you could try to use a 2d area connection within your 2d domain, and model the levee looking structure with the weir equation. You could also try an even larger cell size around it – 100ft….?

[Toby]

You can try to scale your lateral inflows to your input hydrograph, based on drainage area. An HMS model might be better, but more time consuming.

Check out https://water.usgs.gov/osw/streamstats/ and see what data you might be able to find.

[Toby]

If you are happy about where the interpolation has placed your cross sections you can batch cut them from your terrain.

In the geometry editor go to: GIS tools >>> Terrain >>> Cut Profiles (XS….etc)

cheers,

Toby

[Toby]

Check out the examples in the 1d/2d documentation.

http://www.hec.usace.army.mil/misc/files/ras/Combined_1D_and_2D_Modeling_with_HEC-RAS.pdf

[Toby]

Do you have xy coords for you cross sections? If so, add them with the GIS tools in the geom editor -> XS Cut Lines Table. I have also seen when manually adding xs (with no GIS data), that they all get placed over one small point in the geometry and need to be manually moved to see them. Maybe try re-setting the schematic extents, by right clicking in the geom editor to find the xs.

[Toby]

It appears you have a 1d section of river in your 2d extent. Try removing your 1d river, and run in only 2d. If you want a 1d channel and a 2d floodplain you will need to modify your 2d mesh to not cover the cross sections, and create links to your 1d cross sections with lateral structures.

[Toby]

Also of note, there are two downstream boundaries in the 2D area. When I remove all the river connections on one downstream boundary and use a normal depth, the model runs.

[Author]

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