[GRASS-user] r.terraflow for cost path analysis

Colin Wren colindwren at gmail.com
Fri Feb 4 15:13:08 EST 2011

A recent article published in the Journal of Archaeological Science
(http://dx.doi.org/10.1016/j.jas.2010.11.006) proposed a method where
hydrology models could be used on the product of a cost surface
analysis to create a network of paths (instead of just the one made
with r.drain -d). The flow accumulation map would represent the number
of cells in the map from which a least-cost path would pass through
that cell. ie. a flow accumulation of 100 means that 100 cells would
have a LCP that would pass through that cell. You could also calculate
mobility basins (like a watershed), etc.

This is great extension of cost surface analysis except that I don't
think it can be done in GRASS right now. r.cost and r.walk produce a
cumulative cost surface and a "flow" direction surface, but if I'm
right r.terraflow can't take them as inputs because it calculates
everything "in-house".

I was hoping someone could double-check my logic on this or perhaps
suggest an alternative hydrology module(s) which could take the
direction surface as an input instead of calculating everything from
the elevation surface.


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