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Rainfall Factor, R. M average annual R value and an average storm R value <br />is needed to compute Tong-term erosion, in order to calculate the annual <br />sediment yield. Values were calculated using procedures set forth in Barfield, <br />et. al., (1981) as follows: <br />R.~~~d = 27Pz.e for a Type II Storm <br />Where: Pz, = 2-year, 6-hour precipitation in inches <br />= 0.9 inches <br />Therefore, <br />R,~~~, = 27(0.9)~z = 21.4 <br />R„o,,,, = 19.25P~2 <br />Do.~~ <br />Where: Pis the 10-year, 24-hour precipitation in inches and D is the <br />storm duration in hours <br />Therefore, <br />R~,~, = 19.25 1.8 z.2 = 15.9 <br />(,~4)o.+crz <br />Sediment Specific Weight, SW. The specific weight of loose sandy-loam is <br />approximately 85 Ibs/ft'. <br /> <br />10 <br />