[GRASS-user] grass-user Digest, Vol 106, Issue 34

[Thayer Young]

I don't know if you have tried this yet, but you may also want to look at r.terraflow.  It does both D8 (single flow direction) and multiple flow direction (flow is partitioned, according to the steepness of slope, to all directions that are lower than the central cell).  Supposedly you can also switch from MFD to SFD once flow exceeds a threshold, but I have not been successful at doing this.  It would be a simple simulation of channelization though. 

Just set the D8 flag in the options tab, otherwise it will give you MFD by default.  

-Thayer

    Date: Fri, 13 Feb 2015 11:12:30 -0700
From: Thomas Adams <tea3rd at gmail.com>
To: "grass-user at lists.osgeo.org" <grass-user at lists.osgeo.org>
Subject: [GRASS-user] Question about r.watershed and flow accumulation
    grid
Message-ID:
    <CAGxgkWgefeTtcjZWKi3JP8wj79Eb0j3fZsf6hGzT8m9-dgce6w at mail.gmail.com>
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Hello all!

I'm making use of the flow accumulation grid in GRASS 6.4.5 generated from
r.watershed using the SFD (D8) flow algorithm. The DEM has a 250m spatial
resolution. What I'm getting is a break in the flow accumulation in a few
locations which is causing me serious problems with subsequent processing
(with help from some here, I have put together some scripting to generate a
pixel connectivity file for a distributed hydrologic model).

Besides going to a higher resolution DEM, are there any thoughts as to how
I can eliminate these flow accumulation breaks?

Thank you,
Tom

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