improving the quality of imported DEM files to RIVERCAD 2000

hi Chris:
i hope everything is well with you. i am using rivercad 2000 to cut cross sections off of the usgs dem files. these cross sections should be completed by the manual surveying data of the stream from top of the bank to top of the bank and will be used in hec-ras or i assume could be used any other hydraulic program. the problem is the quality of these cross sections particularly in the area around the stream. how can i have rivercad extend the contours in the channel area with the information obtained from surveying of the channel and/or from hard copy of the usgs 7 ½ minute

quads.
best regards
hoss liaghat

Dear Hoss :

There are a couple of ways that you can improve the channel geometry:

1. Cut the cross-section channel geometry separately (using another source of geometry--such as survey data or manually digitizing from a image) from the overbank geometry data. Then, you can have RiverCAD merge the improved channel geometry with the poorer cross-section geometry that was derived from the DEM data. This is done using the Edit Geometry dialog box.

First select the cross-section that you want to import channel geometry into. Then, select Input | Ground Geometry | Edit Geometry. This will display the Edit Geometry dialog box. Then, select <Import...> and select the new geometry that you had previously created. There are several file formats that we support (described in Chapter 3). RiverCAD will allow you to interactively merge the channel geometry into the original cross-section.

2. Using the Image Module, you can georeference the scanned image into the drawing file. This allows you to place a TIFF image behind the cross-section cut line, showing the USGS quad map. Then, manually digitize the channel geometry using the contours on the scanned image.

If you have any additional questions or need any further information, please contact me again.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer