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What are the options for FOSS flow modeling of dilute debris flows in QGIS or GRASS?
Have you, or can you refer me to studies where the authors, tested these models/plugins/functions/etc. for use in lahar modeling?

(Lahars are muddy volcanic flows, I'm interested in ones that will have a very small solids fraction of <10-20%, making some flood models applicable to the study; other add'l info: my field site has poor DEM coverage and is highly channelized, aka not a flood plain)

I am working on developing a FOSS workflow for disaster risk reduction, specifically for using DEMs in FOSS GIS that can either be used as input in separate flow models or with flow models that run in GRASS or QGIS. I know of a few functions that can do this (r.inund.fluv, r.hazard.flood, r.drain, etc) but they seem to be untested for this function.

I was interested in using HEC-RAS but my collaborator feels that it only runs effectively in Arc as HEC-geoRAS. The other model I was interested in (again, Arc) is the D8-algo based LAHARZ model, which (it seems?) is kind of similar to r.drain, at least in theory.

Any information at all on the matter is greatly appreciated!

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Not related to volcanos or lahars, but I've started work on a GRASS script to interface with HEC-RAS. It's not complete yet, but I hope to be able to create a set of cross sections in GRASS, and export to a HEC-RAS geometry file, then read back into GRASS the HEC-RAS generated flood plain. – Micha Apr 3 '13 at 19:44

try massmov2D. it has been used on debris flows, though i think it has no physically-based entrainment capabilities. though this add on is meant for modeling of a specific event, you have to have an estimate or data on the volume of your initially failed material.

there are a lot of papers, though here is one

if you are a lazy wingrass user like me, here is the link for the nightly build of wingrass and its addons:

i think r.hazard.flood is meant to work as a quick tool to estimate, albeit conservatively, a flood hazard area based on the wetness index of terrain.

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Not directly for use with QGIS or GRASS, but flow-r may be a part of such a workflow: Not sure if it is open source, but certainly free. It is probably best used as a first large/regional scale assessment.

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