Misplaced new cross sections

[Emily Holtzclaw]

I am creating some intermediate cross sections in a RiverCAD model. If I want to put the new cross section in between sections No. 1500 and 1600, and I give it the name 1550... but the model is placing it at the very downstream position in the reach. So when I page through the cross sections in order, it shows me (going upstream) 1550, 10, 100, 200, 1500, 1600, 1700, etc...

Why do these new sections get placed at the downstream end of the reach, even though I have numbered it to go in between other sections?

[Chris Maeder]

Dear Emily :

Note that the cross-sections are not misplaced. RiverCAD and RMS uses an AutoCAD array for storing the cross-section grids. Whenever you add a cross-section, the RiverCAD / RMS will attempt to add the new cross-section as near as possible to the start of the array. However, if there are no slots available within the array, it will add the new cross-section to the end of the array.

The AutoCAD array does not guarantee that the cross-sections are in any order, since the RiverCAD / RMS software really does not need them in a particular order. The AutoCAD array is simply a storage mechanism--similar to a matrix--for storing the cross-sections and their related data.

Note that if you cut a cross-section from the topo map, the cross-section is where you placed it on the topo map. However, the cross-section grid is then stored in the AutoCAD array, in the first available slot.

If you want to use the AutoCAD array for your own purposes (such as plotting groups of cross-sections out), then you can have the cross-sections re-ordered in the array in Cross-Section ID order. However, there is not a command or a direct method for doing this. However, there is a fairly easy work around. Simply export your HEC-2 or HEC-RAS model to a HEC-2 or HEC-RAS input data file. Then, reimport the HEC-2 or HEC-RAS model into a new RiverCAD / RMS drawing file. The cross-sections will be ordered in cross-section ID order within the AutoCAD array.

Hope this helps you understand what the software is doing.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com

Thank you for your reponse...

If I export the Hec-RAS model to a Hec-RAS input data file, then reimport into a new RiverCAD file, don't I lose the physical location of the cross sections on my topo? Meaning, then don't I have to redraw (or reassign) the location of all my cross sections so that my floodplain mapping can work?

Emily

Dear Emily :

No, you will not lose the cross-section locations, nor will you need to reassign the cross-sections. RiverCAD / RMS will ask if you want to import the HEC-RAS data into the current river reach. It warns you that any existing cross-section data will be replaced by the imported data.

Then, when RiverCAD / RMS perform their HEC-RAS analysis, they will use the imported HEC-RAS data. However, when RiverCAD / RMS performs the floodplain mapping, it will use the original topo map data.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com

Thank you, I'll try it out.
EMily