I tried several of the commands to compute flow accumulations (r.flow,
r.watershed,r.terraflow). It seems that in all cases, the algorithms are
either D8 (steepest slope), or D-multi (flow weighted among the dowsnlope
neighbors).
I wondered whether there was any GRASS implementation of the D-infinty
algorithm (flow routed to a cardinal and a diagonal cells, depending on the
aspect. Ref: Tarboton, D. G., (1997), "A New Method for the Determination of
Flow Directions and Contributing Areas in Grid Digital Elevation Models,"
Water Resources Research, 33(2): 309-319).
If not, I'd welcome any suggestion. [Processing the 'direction' output of
r.terraflow to find the dominant direction, and linking the aspect map ?]
Thanks a lot in advance
P.
--
Soil & Water Laboratory
Dept. of Biological & Environmental Engineering
Cornell University
ITHACA, NY 14853
Tel: 255.2463
I don't remember exactly the methodology of Tarboton, but I think r.flowmd might be quite close to it. It is similar to r.flow except that it divides the flow to two adjacent downslope cells. So it has a small diffussion effect. Both r.flow and r.flowmd use the D-infinity algorithm in terms of flow direction defined by aspect, but just r.flowmd uses multiple-flow distribution (disperses the flow to more just 1 cell).
The main advantage of r.terraflow is that it contains very fast and efficient algorithms including depression filling, etc. Maybe you can compare these modules to see differences. Any improvement is welcome.
Jaro
SWlab wrote:
Hello,
I tried several of the commands to compute flow accumulations (r.flow, r.watershed,r.terraflow). It seems that in all cases, the algorithms are either D8 (steepest slope), or D-multi (flow weighted among the dowsnlope neighbors).
I wondered whether there was any GRASS implementation of the D-infinty algorithm (flow routed to a cardinal and a diagonal cells, depending on the aspect. Ref: Tarboton, D. G., (1997), "A New Method for the Determination of Flow Directions and Contributing Areas in Grid Digital Elevation Models," Water Resources Research, 33(2): 309-319). If not, I'd welcome any suggestion. [Processing the 'direction' output of r.terraflow to find the dominant direction, and linking the aspect map ?]
Thanks a lot in advance
P.