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In order to obtain a better idea of how the Helley-Smith bedload <br />sampler compares with an established technique of computing bedload, the <br />Helley-Smith bedload results were compared to the Einstein bedload func- <br />tion. Because the bedload data in the Big Sandy River basin were <br />limited, some of W. W. Emmett's numerous data (Emmett, 1975; 1976; 1979; <br />Emmett and others, 1978; Emmett and Seitz, 1974) also were plotted. This <br />comparison is shown in figure 26. Both the Einstein curve and the Brown <br />modification of the Einstein function were drawn to compare with the <br />Helley-Smith bedload data. The dimensionless functions used were defined <br />by Brown (1950) as: <br />4)- PPsF Ps-P <br />F= 2 + 36v2 - 36v and (8) <br />3 $d (Ps/P-1)? [_&d (Ps/P-1) l <br />1= pR'bS (9) <br />qj (Ps-p)d <br />where: <br />(P = intensity of sediment transport; <br />qs = sediment-transport rate of channel width, in pounds per <br />second per foot, measured with Helley-Smith bedload sampler; <br />= gravitational constant (32 feet per second per second); <br />Ps = specific gravity of sediment, which was assumed equal <br />to 2.65; <br />F = dimensionless function of fall velocity; <br />p = specific gravity of water, which is equal to 1; <br />V = kinematic viscosity, in square feet per second, which <br />was assumed to have a value of 1.12X10`5 square feet per <br />second; <br />d = representative size of bed material, in feet, which was <br /> assumed to be the d35 size; <br />d35 = sediment size of whic h 35 percent is finer, in feet; <br />= intensity of shea r on particle; <br />R'b = hydraulic radius due to grain roughness, in feet; and <br />S = energy slope, in feet per foot. <br />The comparison shows some scatter, but an analysis can be made from <br />this plot. The Einstein bedload function is determined by the curve with <br />the equation: <br />37