[GRASS-user] elevation values of watershed basins

Hamish hamish_nospam at yahoo.com
Mon Feb 5 05:19:39 EST 2007

temiz wrote:
> As I see, you are a soil scientist, so you will understand me better.

I'm not, but maybe there is are ideas from other fields which can help-

> The logic of my question is based on finding slopes' length as
> landslide susceptibility parameter ( I accept slope is waterhed
> area).

Perhaps the concept of "fetch"? "The unobstructed region of the ocean
over which the wind blows to generate waves." The idea is the longer the
fetch, the greater height waves can grow. Your slope length seems like a
direct analogy, of sorts. Perhaps there are some fetch calculation
algorithms which may be applicable?

run r.watershed and get a basin and half-basin maps, r.to.vect,
then isolate half basin borders not matching basin borders.

This gives anti-ridges (obtain ridges with "r.param.scale par=feature").
The anti-ridges will be the landslide path? (I guess ridges of flow
accum river map will be the same thing?)

then use the river paths as a MASK and maybe r.cost with slope as cost
layer to see which basin (river) has the biggest cumulative slope?

shooting in the dark,

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