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K1 = [1- (sine A /sin2�)]0.5 <br />where: <br />A = the bank angle with the horizontal; and <br />� = the riprap material's angle of repose. <br />The average flow depth and velocity used in Equation 6 are main <br />channel values. The main channel is defined as the area between the <br />channel banks (see Figure 17). <br />Y <br />C <br />b <br />m r <br />m <br />Left Floodplain L Channel $ Right Floodplalln <br />Figure 17. Definition Sketch; Channel Flow Distribution <br />Equation 6 is based on a rock riprap speck gravity of 2.65, and a <br />stability factor of 1.2. Equation 8 and Equation 9 present correction <br />factors for other specific gravities and stability factors. <br />The following form can be used to calculate D50: <br />CS9 = 2.12 /(SS -1)1.5 <br />where: <br />SS = the specific gravity of the rock riprap. <br />Csf = (SF/1.2)1.5 <br />where: <br />SF = the stability factor to be applied. <br />The correction factors computed using Equation 8 and Equation 9 are <br />multiplied together to form a single correction factor C. This correction <br />factor, C, is then multiplied by the riprap size computed from Equation 6 <br />(7) <br />(8) <br />(9) <br />