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<br />i CURVE NUMBERS <br />The Curve Numbers (CN) are required as an input into the computer program to generate the run-off <br />' quantities. A Curve Number (CN) is an index coefficient that represents the following: <br />' Hydrologic Soil Group <br />• Cover Complex <br />These two factor are used for the empirical analysis. <br />The following approach has been used in selecting the Curve Number (CN) using the CN numbers <br />as shown in Exhibit VQ. <br />1. The Hydrologic Soil Group "A" was established based on the type of soil and high <br />infiltration rate extending over 25% of the basin; balance of the area at 75°% of Soil <br />' Group "B". <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br />LJ <br />2. The Hydrologic Condition "Fair" was established based on the existing ground cover <br />extending over 25% of the basin; the balance of the area at 75% is a "poor" <br />condition. <br />Curve Number of 71 was arrived at by estimating: <br />75% ForestlRange land with Snil Group B Poor Hydrologic Condition: CN = 79 <br />25% PastwelRange Land with Soil Group A Fair Hydrologic Condition CN = 49 <br />Weighted CN = .75 x 79 + .25 x 49 = 71 <br />' PAGE8 <br />