AGNPS-UM Version 3.00 (4 Dec 2003 7:39 pm)

An error in logic exists in the published equation for applying
the USLE-M in grid cells (KINNELL, P.I.A.. (2001). Slope length factor
for applying the USLE-M to erosion in grid cells. Soil and Tillage
Res. 58, 11-17, KINNELL, P.I.A. (2000).AGNPS-UM: Applying the USLE-M 
within the Agricultural Non Point Source Pollution model. Environmental
Modelling & Software 15,331-341.). The error relates to the F factor. 
The published equation for F (Eq 22 in the Soil and Tillage paper) 
results in F values asymptoting to Qcin as U increases when Qcin is 
greater than zero. This causes soils loss to be underestimated by a
factor directly directly related to the Qcin, runoff coeffcient for 
the area upslope of the cell. i.e if Qcin = 0.25 the perivious versions
 will result in cell erosion tending towards being 0.25 times the amount 
that it should. Version 3.00 uses a new slope length factor where the 
effective upslope area is less than the physical upslope area whenever
 the runoff coefficicient of the upslope area is less than that of the 
cell. Details of the new slope gradient factor are contained in a 
paper under review.

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AGNPS-UM Version 4.00 (7 Jan 2004 11.10 am)

Previous versions modified the data inputs for P and C in order to cause 
AGNPS to produce the required data out puts. This version uses dedicated 
versions of AGRUN, the AGNPS executable program, to produce the erosion
outputs for the USLE with the Desmet and Govers and for theUSLE-M without
any need to use non standard input data inputs for P and C.

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AGNPS-UM Version 4.01 (17 March 4.33 pm)

Version 4.01 provides a choice of models that the user can run. The choice
extends from the USLE using the L factor devised by Desmet and Govers, the
USLE with the a L factor which varies with the runoff coefficents for the
upslope area and the whole area, the USLE-M lite (a variant of the USLE-M
that uses USLE C and P factors), to the USLE-M. Each of the models uses an
dedicated version of the AGNPS executable in conjunction with dedicated 
input data files. These files will not operate as data input files for the
original AGNPS executable. 

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peter.kinnell@canberra.edu.au       



