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<br />the variation of velocity from stream reach to stream reacll and specified contributions of <br />excess (as ratios of basin-mean contribution) in different portions of the basin. Another <br />advantage is that the unit duration Can be changed withoJt requiring a new time-area <br />relation to be developed. <br /> <br />The runoff from the contributing areas (between thE' isochrones) which has been <br />translated to the outflow location is in units of volume (in-mi 2 or mm-km '). Hle <br />conversion to proper units of discharge is made through the relationship: <br /> <br />I <br /> <br />Ka, <br />U <br /> <br />(IV-9) <br /> <br />where: <br /> <br />I , ordinate in proper units of discharge (cfs, cm:;. etc) of <br />the translation hydrograph at the end of period i <br /> <br />a, = ordinate in units of area-deptll 01 excess (in-sq mi, mm-sq km, <br />etc.) of the tra 1slation hydrograph at the end of period i <br /> <br />K = conversion f2,ctor to convert a , to I , (to convert in-sq mi to <br />cfs. K = 645; to convert mm-sq km to ems, K = .278 etc.) <br /> <br />L',t = time period of computation interval in hours. <br /> <br />The routing of the translation l1ydrograph through storage at the outflow location <br />is accomplished as follows: <br /> <br />0, <br /> <br />C I, + (1-C: 0 ,.1 <br /> <br />(1\1.10) <br /> <br />where: <br /> <br />0, = outflow from the basin at the end of period i <br /> <br />I, = inflow or runoff from each area at the encl 01 period i <br /> <br />C = dimensionless routing constant <br /> <br />The routing constant, C. is determined for prism type storage as: <br /> <br />C = 2.L\t <br />27rN <br /> <br />(1\1-11) <br /> <br />Colorado Flood <br />Hydrology Manual <br /> <br />7-42 <br /> <br />CRl..lH <br />