Reading the manual pages for v.stream.network, v.stream.order, and
v.stream.profiler in the extensions doc I see details for the input options
but all descriptions refer to raster files.
Are there more detailed docs that show examples using the vector modules
along with the raster modules?
I've a complex, extensive, river network as a vector file. I've not
extracted streams, basins, or watersheds from the DEM and I'd like to
run the v.stream.* modules on my vector stream network. Possible?
TIA,
Rich
Hi Rich,
AFAIK, the tool v.stream.order was developed to work with grass vector files only (no raster input needed). So, the input needed for v.stream.order is the vector lines representing the streams (lines must be connected) and points that define the outlet of each river network that should be processed. I haven't tested v.stream.order for a while, so I am not sure if it still works with newer versions of GRASS?! However, tool comes with a testsuite (see source code) and a working example based on the NC-dataset to test operability of v.stream.order.
HTH,
Johannes
On 03.10.19 22:56, Rich Shepard wrote:
Reading the manual pages for v.stream.network, v.stream.order, and
v.stream.profiler in the extensions doc I see details for the input options
but all descriptions refer to raster files.
Are there more detailed docs that show examples using the vector modules
along with the raster modules?
I've a complex, extensive, river network as a vector file. I've not
extracted streams, basins, or watersheds from the DEM and I'd like to
run the v.stream.* modules on my vector stream network. Possible?
TIA,
Rich
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On Fri, 4 Oct 2019, Micha Silver wrote:
The v.stream.* modules all take vector maps as input.
Micha,
That's what the manual pages suggest.
Maybe yes, but if this refers to the project that you've posted about
recently, then you have a high resolution LIDAR-based DEM of the basin.
These v.stream.* modules are intended to work with vector outputs from the
r.stream.* modules.
I thought so.
If you are going to ignore that and use a vector stream network from some
other source, then be aware:
1- This alternate stream network must be topologically correct
2- Stream vector segments should all be in downstream direction (the
outlet reach *must* be directed downstream).
3- You might not be able to make use of the DEM for other analyses, since
it won't match the stream network.
This answers all my questions. I've no idea how the vector river network
data were created. I've also decided that for the intended audience the
results of the v.stream.* are overkill.
Thanks very much,
Rich
On Fri, 4 Oct 2019, Johannes Radinger wrote:
AFAIK, the tool v.stream.order was developed to work with grass vector
files only (no raster input needed). So, the input needed for
v.stream.order is the vector lines representing the streams (lines must be
connected) and points that define the outlet of each river network that
should be processed. I haven't tested v.stream.order for a while, so I am
not sure if it still works with newer versions of GRASS?! However, tool
comes with a testsuite (see source code) and a working example based on
the NC-dataset to test operability of v.stream.order.
Johannes,
Yes, this does help. The river network is very large and complex and adding
points at each confluence would take a very long time. After stepping back
and thinking how the outputs from the v.stream.* modules would be received
by the intended audience I realize that this detail is meaningless to
non-technical decision-makers.
Thanks very much,
Rich