[GRASS5] Re: [GRASSLIST:7895] Re: Hutchinson's Adaptive Alogrithm for sound DEMs?

Jaro Hofierka hofierka at geomodel.sk
Tue Aug 16 06:19:41 EDT 2005

Maciek Sieczka wrote:

>> Moreover, rivers sometimes do not follow exactly adjacent terrain as the
>> river flows in the channel, etc.
> That could be overcome by "stream burning" I guess. Each cell which falls
> into the watercouse is lowered for, say, 0.1 m. This usualy does the trick.


The problem is a bit more complex than you are suggesting here. Rivers 
on lowlands flow usually within the walls (sediment deposits), so the 
river is actually above the terrain. I am not sure if "stream burning" 
helps in this case, at least it cannot be fully automated.
Anyway, there are plenty of algorithms that handle water courses/flows, 
DEM depresion filling, etc. The excellent module for this application in 
GRASS is r.terraflow, you even do not need a hydrologically-enforced DEM 
to get all water into the outlet.
Some of your suggestions for v.surf.rst are interesting, e.g. 
faults/breaklines, other problems can be solved outside v.surf.rst in a 
separate module. Perhaps Helena can help to select reasonable 
improvements for v.surf.rst that are worth of effort.


>> So, there is no need for "massive" manual editing for these points.
>> At that time we were using just "site" version of the RST method, so we
>> needed points to enforce the shape of resulting surface.
> As you might have read on the list Dylan and I (hopefully more Folks will
> join us) are looking for somebody who could extend v.surf.rst to handle
> watercources, faults and ridges (else ?). Spread the word please. If enough
> people join us we can think of a financial reward for the developer. Maybe
> you?
> Thank for your input Jaro.
> Best,
> Maciek
> P.S.
> Everobody who is interested in adding faults, watercouses (including their
> flow direction - to be able to drain through the slope and to model flow
> splits), ridges and stream burning functionality into v.surf.rst (or other
> DEM interpolation program in GRASS) please report. Say whether you are
> interested as a:
> 1. user who needs this functionality (give us a sign, it doesn't hurt :);
> the more of us the better chances!)
> 2. user any experienced in incorparating faults, watercouses, ridges into
> DEM who could contribute information and advice
> 3. developer willing to coordinate the project from the programming side
> 4. programmer willing to help
> 5. users willing to contribute in testing and writing the docs
> Also, please let us know if there is any other functionality you would find
> beneficial for DEM interpolation. Maybe could be done by the way.
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