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TABLE 1 <br /> MEASURED AND ESTIMATED RALSTON CREEK WATERSHED AREA CHARACTERISTICS <br /> Drainage Area: 38.3 square miles <br /> Maximum Watershed Relief: 3,450 feet <br /> Approximate Main Channel Length: 14.8 miles <br /> Approximate Main Channel Slope: 4.4 percent <br /> Approximate Watershed Land Slope: 38.0 percent <br /> Hydrologic Soil Groups: <br /> 1 2 % A; 35 % B; 6 % C; 57 % D <br /> Estimated Runoff Curve Number: <br /> 2 3 63 for AMC-II condition; <br /> 81 for AMC-III condition <br /> 1 As defined by Soil Conservation Service National Engineering <br /> Handbook, Section 4, Hydrology, Chapter 710, 15 and 21. <br /> 2 A runoff curve number represents the relative value of the watershed <br /> hydrologic soil-cover complex as a direct runoff producer. A greater <br /> amount of direct runoff is expected from a storm for a watershed with <br /> a higher runoff curve number than from one with a lower number. <br /> 3 o AMC-II . -The average case for annual floods, <br /> that is, an average of <br /> the conditions which have preceded the occurrence of the maximum <br /> annual flood on numerous watersheds. <br /> o AMC-III .-When heavy rainfall or light rainfall and low temperatures <br /> have occurred during the 5 days previous to the given storm. <br /> -11- <br />