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I'm also not clear what you are asking. But risking a guess:<br>
You could run r.water.outlet *1 time* to get the basin. Then use
that raster as a MASK, so that the next process will address only
the pixels within the basin. Now do a loop with r.univar on all
14,000 flow rasters, and you'll get 14,000 results with total, min,
max, mean, etc of the basin pixels for each of the flow rasters.<br>
<br>
--<br>
Micha<br>
<br>
<div class="moz-cite-prefix">On 08/31/2017 09:30 PM, Thomas Adams
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAGxgkWhJ8PWAh+Av1u5KUcLHvqa5NZZvqx+SQzJ0eVz2h3e-0A@mail.gmail.com">
<div dir="ltr">
<div>
<div>Ken,<br>
<br>
</div>
You "want 14,000 values" of what?? Your original email stated
you were "trying to determine flow past a drainage basin
outlet" -- r.watershed does NOT do this, if indeed this is
what you want. And you say you have "14,000 flow rasters to be
used as input" -- what exactly are these 'flow rasters'; what
is your goal? I may not understand...<br>
<br>
</div>
Tom<br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Thu, Aug 31, 2017 at 2:24 PM, Ken
Mankoff <span dir="ltr"><<a
href="mailto:mankoff@gmail.com" target="_blank"
moz-do-not-send="true">mankoff@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="auto">
<div>Hi Tom,</div>
<div><br>
</div>
<div>I have 1 DEM and 14,000 flow rasters to be used as
input. I want 14,000 values, one at a specific
coordinate from each acc output. </div>
<div><br>
</div>
<div>I can do this by running r.watershed 14,000 times.
That is slow, unless I'm missing something (e.g. It
works with I.group variables or Time Series data more
efficiently). </div>
<div><br>
</div>
<div>An alternative approach is possible if I knew the
complete drainage basin *and* the fractional value of
each cell that contributed to the basin. In this case
I don't need to route. But basins from r.watershed or
r.water.outlet, I think, use SFD not MFD (no cell is
ever in 2 basins, are they?), and I don't know how to
get the fractional contribution from each cell. </div>
<div><br>
-k.
<div><br>
</div>
<div>Please excuse brevity. Sent from pocket computer
with tiny non-haptic feedback keyboard. </div>
</div>
<div>
<div class="gmail-h5">
<div><br>
On 31 Aug 2017, at 19:59, Thomas Adams <<a
href="mailto:tea3rd@gmail.com" target="_blank"
moz-do-not-send="true">tea3rd@gmail.com</a>>
wrote:<br>
<br>
</div>
<blockquote type="cite">
<div>
<div dir="ltr">
<div>
<div>
<div>Ken,<br>
<br>
</div>
I'm confused about what you are trying to
do with r.watershed, because the output
from the module is:<br>
<br>
accumulation=name <br>
Name for output accumulation raster map <br>
Number of cells that drain through each
cell <br>
tci=name <br>
Name for output topographic index ln(a /
tan(b)) map <br>
spi=name <br>
Stream power index a * tan(b) <br>
Name for output raster map <br>
drainage=name <br>
Name for output drainage direction raster
map <br>
basin=name <br>
Name for output basins raster map <br>
stream=name <br>
Name for output stream segments raster map
<br>
half_basin=name <br>
Name for output half basins raster map <br>
Each half-basin is given a unique value <br>
length_slope=name <br>
Name for output slope length raster map <br>
Slope length and steepness (LS) factor for
USLE <br>
slope_steepness=name <br>
Name for output slope steepness raster map
<br>
Slope steepness (S) factor for USLE <br>
<br>
</div>
I think you want a hydrologic model, and
r.watershed is NOT that. What are you trying
to obtain?<br>
<br>
</div>
Tom<br>
<div>
<div><br>
<br>
<br>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Thu, Aug 31,
2017 at 1:47 PM, Ken Mankoff <span
dir="ltr"><<a
href="mailto:mankoff@gmail.com"
target="_blank" moz-do-not-send="true">mankoff@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Hi List,
<div><br>
</div>
<div>I'm trying to determine flow past
a drainage basin outlet. The
complicating factor is that I need
to do this each day for 40 years. If
I do "r.watershed" ~14,000 times
I'll get the results, but it will
take 3 days. It seems that
r.watershed is likely calculating
many things each time through the
loop. Is there a more efficient way
to this? A flag to r.watershed that
isn't documented? Something with
time-series?</div>
<div><br>
</div>
<div>Alternatively, because I only
need the flow at the outlet, I could
calculate the basin, not route the
flow, and instead sum the values in
the basin. I assume this would take
seconds or minutes rather than days.
In this case I'm not sure of the
best way to define the basin. I
tried doing r.water.outlet upstream
from the outlet, but I think this
uses SFD, which means the basin may
be significantly underestimated.</div>
<div><br>
</div>
<div>I also tried inverting/flipping
the DEM and then running r.watershed
with convergence=1, and a flow equal
to 0 everywhere except 1000 at the
outlet (now the source due to the
inversion) to see where it flooded
upstream (now downstream due to the
inversion). This didn't seem to
work... because basins are filled
and flow routes to the edge of the
DEM, I could not pick out the </div>
<div><br>
</div>
<div>Any advice how to either a)
efficiently route 14,000 FLOW
rasters over 1 DEM or b) determine
the full basin will be much
appreciated.</div>
<div><br>
</div>
<div>Thanks,</div>
<div><br>
</div>
<div> -k.</div>
</div>
<br>
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<br>
<pre class="moz-signature" cols="72">--
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918</pre>
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