Culverts in Hec-GeoRAS

Discussion created by johngalt82 on Mar 1, 2012
Latest reply on Mar 1, 2012 by Meadmw
Hi one and all,
Noob to the forum from Exeter, England.

Im working on a high level piece of flood analysis of a small catchment within the cities boundaries.
I have been using ArcGIS 10 to import lidar data, then using the hydro/spatial/3d analysis tools to get slope data, contours and the relevant tin surfaces.

The catchment in question contains two steam reaches which are connected by a culvert.
My question is regarding the digitisation of the stream and the culvert. i have crated the layres in the RAS Geometry and used the editor to sketch the course of the upper reach of the stream. When i get to the culvert should i......

a) stop, then start the new stream digitisation for the lower reach and then digitise the culvert seperately in the gap.

b) continue the stream from top to the very bottom including the culvert.

If i do b) do i then have to trace directly over the line where the culvert is situated?

I only ask as my thought is that if i draw the line from top to bottom including the culvert, when i set the stream attributes will it think that the culvert is actually lying on the surface of the tin?

Hopefully that makes sense as these things are always tricky to put into words....

The end result im hoping for, is to extract the data into Hec-RAS and complete some more in depth hydraulic analysis.

If anyones got any words of wisdom or guidance that would be great.
Many thanks