[GRASS-user] Some questions about DEMs

[David Townshend]

In the end I combined the contours and points and used r.fillnulls to
generate a 5m DEM.  It seemed to run quite a bit faster than
r.surf.contours and gave fairly good results. Not perfect, but given
the data I'm starting with, its not bad either.

My next problem is getting r.sim.water working. Does anyone have any
experience with this?  I have a quite a few questions about it:
 - What exactly do the diffusion terms and weighting factor do?
 - What is the best way of simulating hydraulic controls such as
bridges or weirs (is it even possible)?
 - Is there a correlation between the time used for iterations (niter)
and the storm duration? If not, then how do I determine it?
 - How applicable is this model to flow in rivers?
 - I want to try to use this model for floodline generation. Does
anyone know of any work that has already been done on this, or is the
model totally unsuitable?

I had hoped to figure some of this out by myself, but whenever I try
running the simulation I get empty output.  Can anyone help?

David