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<br />26 <br /> <br />4. Sediment-Transport Function: <br /> <br />SEDIMENT -4H ca 1 cul ates tota 1-1 oad sediment di scharge for an ideal i zed, <br />single, median grain size. The basic concept is similar to Einstein's bed- <br />load function; however, in SEDIMENT-4H the sediment concentration in the bed <br />layer is set to a maximum and is assumed to be transported at the local mass- <br />weighted velocity. The concentration of sediment in the bed layer is assumed <br />to be dependent on the amount of sediment in suspension, but not to exceed <br />100 1 bs/cu ft. <br /> <br />The Rouse (1937) equation for the vertical distribution <br />sediment concentration in a fully-developed, turbulent flow is <br />the depth-averaged sediment concentration, <C>, and the <br />distribution is expressed in dimensionless terms by <br /> <br />of suspended- <br />norma 1 i zed by <br />concentration <br /> <br />~ (I.) = ~ t. (t. (1 II. - 1) I (1 - t.))~; I. ) t. <br /> <br />.... (2-40) <br /> <br />and <br /> <br />~ (I.) = ~ <br />t. <br /> <br />I. < t. <br /> <br />....(2-41) <br /> <br />where <br />I. = y/d <br />d = flow depth <br />~ (I.) = C(Y)/<e> <br />t. = aId (nondimensional sublayer thickness) <br />a = reference level where C is given <br />~ = V IKU* <br /> S <br />Vs = sediment fall velocity <br />K = von Karman's constant <br />U* = shea r ve 1 oc ity <br /> <br />The sediment concentration in the sublayer, ~ , is obtained from the following <br />t. <br /> <br />relation: <br /> <br />1 <br />f ~ (I.) d).. = 1 <br />o <br /> <br />....(2-41) <br /> <br />Therefore, <br />