The important rainfall variable for the effect of cover-management practices is cumulative erosivity.
	The effect of supporting practices that are strongly influenced by runoff are much more dependent on the effects of a few, major intense storms.
	The effect of these few storms is captured in RUSLE2 by use of the10 Yr EI storm.
	For example, contouring is less effective in the Southern US than in the Northern US because of intensive storms.  Use of the 10 yr EI storm in computing the effectiveness of contouring allows RUSLE2 to capture that difference.