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FLOOD LEVEL CALCULATIONS <br />2/3 <br />V -1.49 S'lz (Ai) <br />n; P,. <br />Vi = Water velocity in channel (fps) <br />Ai = Channel cross sectional area (ft) <br />Pi = Channel cross sectional wet perimeter (ft) <br />S = Channel slope (percent grade) <br />ni = Manning's number (gravel lined channel) <br />Event A, (ft) P, (ft) i n, V, (fps) S Volume (cfs) <br />10 year 24 475.00 182.80 0.02 16.05 1.3% 7,626.05 <br />10 year 24 hour event volumetric flow rate = 7,600 cfs <br />Cross-sectional area and perimeter determined from 10 Year Cross Section Detail. <br />Approximate water surface level = 5360' <br />The water level is based on the known flow of 7,600 cfs provided by Crane & Associates. <br />Manning's equation was used to determine the height of water necessary to pass that <br />known flow at that point on the river.