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<p>Hi Rich</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 10/17/18 8:43 PM, Rich Shepard
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:alpine.LNX.2.20.1810171039230.25109@salmo.appl-ecosys.com">
The r.flow manual tells us that "Flowline density downhill or
uphill
<br>
output is given in a raster map flowaccumulation. The value in
each grid
<br>
cell is the number of flowlines which pass through that grid cell,
that
<br>
means the number of flowlines from thec [sic] entire map which
have segment
<br>
endpoints within that cell."
<br>
</blockquote>
<p><br>
</p>
<p>If my understanding is correct, the r.flow module output raster
"flowaccumulation" gives (as in manual that you quoted) the
*number* of flow lines flowing into each cell. This is not
upstream contributing area in the usual sense. Rather it describes
stream density. If you check the values in cells that are
downstream right in the streams, you'll see that they have a low
value (i.e. small number of upstream flow lines that end in that
cell). <br>
</p>
<p><br>
</p>
<p>If you want the actual upstream contributing area (flow
accumulation in the usual sense) then go back to the r.watershed
module and use the "accumulation" output option. Then, your
non-technical audience will easily understand the legend referring
to "upstream contributing area". <br>
</p>
<p><br>
</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:alpine.LNX.2.20.1810171039230.25109@salmo.appl-ecosys.com">
<br>
Please suggest a legend title for this map that nontechnical
audiences
<br>
will understand. Can I explain this map in the report text as "the
upstream
<br>
areas draining to downstream points?" Or, is there a better,
nontechnical,
<br>
way of interpreting this map?
<br>
<br>
TIA,
<br>
<br>
Rich
<br>
<br>
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</blockquote>
<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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