[GRASS-user] Time of Concentration/Travel Time Calculation

Weier, Mitchell S. mweier at nd.gov
Fri May 10 09:26:34 PDT 2013


I am working on developing a process that will calculate time of
concentration of drainage basin.  It seems that r.stream.distance comes
close to accomplishing this except I would like to weight each cell by a
velocity factor which would give me the travel time.  I plan on developing
velocities for each cell which depend on factors like contributing area,
slope, land use etc..

The problem is I need to apply this weighting factor during the
accumulation of distances so the cumulative effect of the varying
velocities are represented.  Seems like r.stream.distance would work great
except there isn't an option to apply the weighting factor.  I can apply
the weighting factor to the flow accumulation grid in r.watershed, but
that accumulates the time the wrong way.  Anyone know of a way to pull
this off?

Also, I am aware there is an r.traveltime add on, but I would prefer
something that allows me to calculate velocities using different methods.


Mitch Weier

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