USLE

[Helena Mitasova]

>From: tom%alla@[155.84.92.2] (Tom Nelson)
>
>Betty Alex of the N.P.S. at Big Bend requested this posting.
>
>She is seeking all / any information on automated Universal Soil Loss Equation calculation using GRASS. 
>Bibliographic references articles or other publications are much appreciated.
>
>all answers are appreciated.
>please reply either to the list or 
>  tom%alla@[155.84.92.2]                                            |
>
>Thanks
>_____________________________________________________________________
>|                                                                    |
>|  Tom Nelson                                                        |
>|  Corps of Engineers                                                |
>|  Fort Worth, Texas                                                 |
>|  (817) 334-2095                                                    |
>|                                                                    |
>|  tom%alla@[155.84.92.2]                                            |
>>|____________________________________________________________________|


Tom,

(I tried to send this to your email, but it bounces back, so I have
to post the answer to the list)

I have done lots of erosion/deposition modeling in GRASS.
 A simple general article
about how we are doing it is in GRASSClippings Spring 1993.
I have a more detailed paper submitted to I.J.of GIS, I can send Betty
a copy if she is interested. An important tool for doing USLE/RUSLE/Unit
Stream Power based erosion modeling is program r.flow which is not part
of standard GRASS4.1 but is available on moon and easy to install and run.
The major issue is the proper DEM - I have got the best results by
creating the DEM from digitized 1:24000 topo map contours using s.surf.tps
with output in cm(! this is very important in relatively flat terrain)
 or from directly measured elevation data interpolated
by s.surf.tps. In mountainous areas the standard 30m DEM worked too,
although the results were not as good as for the previous cases.

Helena Mitasova
U.S.Army CERL
Champaign, IL 61821
ph: 217-352-6511 ext 686
email: helena at zorro.cecer.army.mil