For the infiltration, if you can determine the soil texture, then you
could estimate the Green-Ampt parameters using 
What do you want to do in that area? Perform hydrological/overland
If it is the case, you might give Itzï a try:
Some of the parameters could be estimated (like friction coefficient).
 Rawls, W., Brakensiek, D., and Miller, N. (1983). "Green‐ampt
Infiltration Parameters from Soils Data." J. Hydraul. Eng.,
2016-09-22 13:09 GMT-05:00 Rich Shepard <rshep...@appl-ecosys.com>:
> The project area -- in farmland -- is small (< 20 ha) and essentially
> flat with elevation differences less than 1 meter. The LiDAR raster cells
> (imported from ARC Grid format) have a cell size of 3x3 international feet;
> elevation resolution is 0.013 feet.
> While r.slope.aspect generates an aspect map, the slope map is blank. The
> maps for dx, dy, and relief display variations.
> While I have some soil data, it's sparse and I haven't (yet) found
> infiltration rates; the rainfall data is very low and from a station several
> miles away. I probably do not have all required input data for r.sim.water
> or r.watershed.
> Based on your much more extensive experiences applying GRASS to limited
> areas please suggest approaches that might be appropriate for this project.
> It might be that all I can do is create detailed contour maps of the area
> and describe the situation qualitatively without robust quantitative
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