[GRASSLIST:2154] Re: stream networks

[Radim Blazek]

On Thursday 08 January 2004 03:41, Christopher Fonnesbeck wrote:
> I am trying to use GRASS 5.7 for some hydrologic modeling; in
> particular, I need to develop a stream layer composed of segments that
> know what their downstream neighbour is. I know there are functions
> like r.watershed that will produce a stream layer, but not a "network"
> as I describe, and there are network functions that I generally see
> used for roads, but not streams. Could these be combined in some way to
> produce what I need, or am I barking up the wrong tree? Any advice
> would be most helpful.

I don't the output from r.watershed, if lines are oriented down 
and connected at nodes, you can place new points at nodes (v.net operation=nodes), 
assign categories to points and print start and end point category for each 
point (v.net operation=report). Then, with some scripting, extract 
the downstream neighbour for each line, i.e find which line has as starting point 
the point which is end point of the line.

Radim