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<br />1. Estimate a travel time, T, in hours, of peak flow through the <br /> <br />reach. This estimate is made fromcompprisons of peaking times of <br /> <br />recorded floods if data are available, or from flow velocity <br /> <br />estimates for the reach. <br /> <br />2. The travel time, T, is divided into two components; transla- <br /> <br />tion time, Tr,in hours and storage time, Ts' in hours, preserving <br /> <br />the relationship, T = Tr + Ts' <br /> <br />a. Experience has shown that making Ts = O.ST gives good <br /> <br />routing results for natural st.ream channels, If stream channels <br /> <br />are such that floods cause. large overbank flooding and temporary <br /> <br />storage, the ratio, Ts:T may be increased. If Ts is made <br /> <br />equal to T,the stre~ reach is assumed to act as a reservoir. <br /> <br />3. A routing time interVal, t in hours, is selected, usually <br /> <br />equal to or less than 0.5T8. <br /> <br />4. <br /> <br />Routing computations are made by <br /> <br />02 = 01 + K(Il + 12 - <br /> <br />the equation: <br />YfJ;r-':" <br />2fJ1) <br /> <br />where 11,12 - Inflow, consecutive instantaneous discharges at the <br /> <br />head of the. reach; <br /> <br />01' O2 = Outflow, successive incremental instantaneous <br /> <br />discharges at the end of the reach; O2 being the <br /> <br />outflow effected by II and 12.and the preceding <br /> <br /> <br />outflow Olj <br /> <br />20 <br /> <br />;;_i~_..,. <br /> <br />.-......~~,.-...or.,.. . .,...~J.,. <br /> <br />..."......... . ....".,..., . ~ <br /> <br />:, '" <br /> <br />,.-~,',...~ <br /> <br />..<l.-. <br /> <br />''- <br /> <br />. <br />