[GRASSLIST:2878] Re: finding downstream paths

[Radim Blazek]

On Monday 08 March 2004 20:18, Christopher Fonnesbeck wrote:
> I am attempting to determine the downstream polyline for each reach in
> a stream network, so that I can route disturbances through the network
> (e.g. floods). I have tried determining the start and end point cats
> for each polyline using v.net with the report operation, but it shows
> each cat as zero:
>
> 1 0 0
> 2 0 0
> 3 0 0
> ...
> 2043 0 0
> 2044 0 0
> 2045 0 0
> 2046 0 0
>
> Clearly this should not be the case. I have a contiguous network of
> polyline streams.

Do you have points with cats on nodes? Run
v.net input=net1 output=net2 operation=nodes
v.category input=net2 output=net3 type=point option=add field=2
v.net input=net3 operation=report afield=1 nfield=2

Radim