r.flow
r.flow.barrier - Construction of flowlines, flowpath lengths, and flowaccumulation (contributing areas) from a raster digital elevation model (DEM).
Raster (r.*)
ParameterRaster|elevation|Elevation|False
ParameterRaster|barrier|Barriers|False
ParameterNumber|skip|Number of cells between flowlines|None|None|7
ParameterNumber|bound|Maximum number of segments per flowline|None|None|1609
ParameterBoolean|-u|Compute upslope flowlines instead of default downhill flowlines|False
ParameterBoolean|-3|3-D lengths instead of 2-D|False
*ParameterBoolean|-m|Use less memory, at a performance penalty|False
OutputVector|flowline|Flow line
OutputRaster|flowlength|Flow path length
OutputRaster|flowaccumulation|Flow accumulation