[GRASS-user] sub-basins of exactly 300 sq km size in a large basin

Markus Metz markus.metz.giswork at googlemail.com
Sun Nov 20 06:48:48 EST 2011

Pankaj Kr Sharma wrote:
> Dear grass users,
> I am trying to find sub-basins and their outlets exactly for each 300 sq.
> km. in a bigger basin.
> I think accumulation value indicates the no. of cells draining at a cell.
> And will thus be a good starting point for such calculation.
> The other option is to start backwards from the basin outlet and keep on
> investigating upwards in a stream network.
> Can someone provide some hint / help in this regard.
> Thanks.

You could run r.watershed in SFD mode, then select all flow
accumulation cells whose values are a multiple of 300 sq km converted
to number of cells. These cells can then be used as input for
r.stream.basins to determine the corresponding basins.


Markus M

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