HEC-GeoRAS cross section points

[mcmillen]

Hello-

I am using HEC-GeoRAS to extract cross section information from a terrain model that I have previously generated. The channel that I am analyzing has a flat bottom.

I can generate all of the layers without any problems and can populate all centerline, bank, flowpath, and cross section fields. Looking at the cross sections with the HEC-GeoRAS viewer yields channel sections that look good.

The problem is that when I export the GIS data and import the file in HEC-RAS, the channel bottoms are slanted from one end to the other, when they should be flat. Examining the nodes in ArcMap shows that four or five nodes across the channel bottom all have identical elevations, as they should. For some reason, only one point in the HEC-RAS import file has this elevation and subsequent points are slanted up so that the channel elevation near the opposite bank is too high. All other elevations above the channel for the left and right banks are correct.

Is there a reason why HEC-RAS won't properly plot several points of equal elevation for the import file? I checked the xml export file, and that is correct. The problem lies somewhere in importing the data I believe.

Any suggestions would be greatly appreciated. I'm using ArcGIS 9.2 and the most recent HEC-GeoRAS version available from ESRI's ftp site.

Thanks-
Frank

[Paul M]

the only thing i can think of is point filtering? do you have any kind of point reduction function turned on? some kind of rounding? i have been using the GeoRAS with ARC9.1 and didnt get anything like this. it brings over scads of points, too many for HEC-RAS, and then i filter them down to whatever. but that is usually done after importing.