[GRASSLIST:5152] Re: finding sinkholes

[Brad Corner]

Hi Johannes,
 Maybe this is a very quick and dirty way but fill the pits, then subtract
your original map from the filled map.  That should isolate the depressed
areas.  I'm no expert with GRASS thats for sure but I would think that
r.fill.dir / r.mapcalc* fits your purpose.  But I'm not so sure if this
works on float point data in grass5... I submitted a question to the list
about the compatiability of floating point rasters and r.watershed with no
response.
Hope this provides some ideas,
bjc
----- Original Message -----
From: "Johannes Bühler" <johannesbuehler at oderbruecke.de>
To: <GRASSLIST at baylor.edu>
Sent: Wednesday, December 04, 2002 8:50 PM
Subject: [GRASSLIST:5150] Re: finding sinkholes


> Hi John
> > It seems to me that the size of the sinkhole and the resolution of your
> > dem would have a serious effect on what you could identify.
> right, but for my purpose the quality of the data is good enough. perhaps
> sinkhole is not the most felicitous word. I mean "Depressed areas".
>
> > Valleys with
> > internal drainages such as bolsons
> by the way what are bolsons (my english dictionary does not include this
> word)
> > should show up, but a true sinkhole
> > such as you see in karst topography might be too small to register,
> > depending on dem resolution.  For bolsons, an hydrological analysis of
> > drainage patterns for centripetal systems might work to isolate discrete
> > closed basins.
>
> i just need a simple operation/command like "find all depressed areas"
> Nothing complicated.
>
> Johannes
>
> --
> --          Johannes Buehler
>    __O      Feldtstr. 45
>  =`\<,      14789 Greifswald
> (=)/(=)     johannesbuehler at oderbruecke.de
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