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<br />- Average Runoff <br />Average runoff calculated using equation 10.10 from the National <br />Engineering Handbook, Section 4 - Hydrology: <br />(P+O.SS) <br />Where Q runoff quantity in inches <br />P rainfall amount (inches) <br />S (1000/CN) - 10 (CN i s the average curve <br />number) <br />- Equivalent Area <br /> <br />• - Equivalent Peak Discharge <br />From Figures 23-1 through 23-3, Peak Rates of Discharge for <br />Small Watersheds (24-hour Type II storm duration) <br />- Actual Peak Discharge <br />(Actual Area/Equivalent Area) x Equivalent Peak Discharge x <br />Slope Adjustment Factor <br />- Peak Discharge <br />Actual Peak Discharge x Average Runoff for particular storm <br />event <br />- Runoff Volume <br />Average Runoff for particular storm event x Maximum Drainage <br />Area <br />23-14R Revised - August, 1990 <br />