In short, r.watershed, without depression input, will route water in and *up* and out of depressions in the terrain to illustrate the complete downward path. This is why no DEM filling is necessary. By entering in known (substantial and impactful) depressions, the water does not route out of it.<br>
<br>The known depressions are especially useful when delineating sink-watersheds or internally drained, but can play a role in depressions where water doesnt flow out of the depression.<br><br>Mark<br><br><div class="gmail_quote">
On Thu, Jan 29, 2009 at 10:12 AM, Georg Kaspar <span dir="ltr"><<a href="mailto:georg@geofs.de">georg@geofs.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi,<br>
when providing a binary depression layer for r.watershed, areas around<br>
those depressions will be left out in the resulting basin map. Are<br>
those areas the watersheds of the given depressions?<br>
According to Markus Neteler's book "Open Source GIS", r.watershed<br>
"does not require filling of depressions in DEM prior to it's<br>
application [...]". What will be the difference if I use a<br>
depressionless DEM (with/without binary depression layer)?<br>
Thank's for your help. I'm new to this field so please excuse any<br>
missing base knowledge!<br>
Best regards,<br>
<font color="#888888">Georg Kaspar<br>
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