2D output – How to avoid interpolation of output?

[Anonymous]

Hi,

I’m investigating the differences between mesh resolutions on flow paths and flow propagation in urban areas after adding precipitation using the precipitation boundary condition. However, I have run into problems getting the correct output from HEC-RAS. When producing a depth or velocity raster, HEC-RAS interpolates the values between cells to produce a smoother profile, although I would like to get the actual computed depths and velocities for each cell. I haven’t been able to find out how to get this output, any ideas?

The interpolation causes large problems when rising houses in the DEM. The large differences between WSE between a roof top and the ground causes HEC-RAS to produce interpolated depths that are way too big.

/Alexander

[cameron]

all output can be found in the hdf file if you want to create a raster from that. In Mapper if you right click on the results label, select the render option and it will give you a chance to change it hybrid (default) to Horizontal (which is what it really computes).

[Anonymous]

Thanks Cameron!

In Mapper, this seems to work when the results are generated for the current view, although it doesn’t change the results that are stored (saved to disk) (these results are still interpolating when adding new maps after the map render mode has been changed to horizontal). Do you have any idea how to fix this?

My goal is to export the horizontal depth raster into Arc-GIS. Thanks a lot!

/Alex

[cameron]

It should export the horizontal results when you have it generate the stored rasters, unless they changed something with the latest version of HEC-RAS.

[Anonymous]

I found out that others have had the same problems (see comments in links below). It seems to be a bug that is supposed to be corrected in future versions. I did not manage to get the correct result from neither 5.0.1 nor 5.0.3.

http://hecrasmodel.blogspot.se/2016/10/creating-static-results-maps-shapefiles.html

There is a good description of the risks using interpolated results in the release note from 5.0.3: https://drive.google.com/file/d/0B0bpiyLiUeRXczlDX2dYTWxkOTQ/view

/Alex

[Leo]

Has anyone solved this problem?
I am experiencing the same issue. I have a 30 by 30 feet terrain data and when I save the maximum depth to the disk (using the Raster based on Terrain option), the quality of the TIFF file changes and the results are shown in 30×30 ft squares because of the terrain. Is there any way to solve this problem, or to use the Raster that is stored on the fly (in memory) for ArcGIS purposes?

Thank you,

[Author]

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