[GRASS-user] r.watershed

[Markus Metz]

On Wed, Jan 17, 2018 at 6:30 PM, Shane Carey <careyshan at gmail.com> wrote:
>
> Hi,
>
> I was wondering if someone could tell me how r.watershed works in terms
of creating stream network. I was of the opinion it just mapped a river
from A to B based on the least cost search algorithm where elevation is the
"cost"!

In r.watershed, there is no "A to B". The least cost search starts with
potential outlets (many B's) and determines flow directions for all
non-NULL cells (many A's).

>
> However, it also calculates flow directions and flow accumulations - Are
these just an added bonus?

Added bonus is flow accumulation using the determined flow directions.

Further added bonus is stream network extraction, essentially flow
accumulation >= threshold.

Markus M
>
> Thanks
>
> --
> Le gach dea ghui,
> Shane Carey
>
>
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