Hello Hydrologist Types!

I have a question about the Universal Soil Loss Equation.  I have seen
references to many ways of calculating the factor 'LS'.  I have an
equation from Novotny and Chesters, and I also have a matrix in a soil
erosion handbook from New Jersey.  Is there a cannonical method?

Also, with regard to a raster GIS, I assume that the length of slope, one
input to figuring the factor 'LS', is the distance across each individual
cell, or the diagonal distance.  How do you decide which to use?  Does it
matter?  What algorithm does GRASS use to compute slope anyway, and is this
distance question related?

Any help will be greatly appreciated!

garyo@hydroqual.com
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An engineer?  I had grown up among engineers, and I could
remember the engineers of the twenties very well indeed:
their open shining intellects, their free and gentle humor,
their agility and breadth of thought, the ease with which
they shifted from one engineering field to another, and, 
for that matter, from technology to social concerns and art.
Then, too, they personified good manners and delicacy of taste;
well-bred speech that flowed evenly and was free of uncultured
words;  one of them might play a musical instrument, another
dabble in painting; and their faces always bore a spiritual
imprint.

	                            from The Gulag Archipelago
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