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<br />CFS <br /> <br />Qrl = 11440 <br /> <br />\:ACTUAL <br /> <br />/ , <br />, , <br />,- <br />I <br />/. <br /> <br />ROUTED HYDROGRAPH <br /> <br /> <br /> <br />ASSUMED EQUIVALENT <br />TRIANGULAR HYDROGRAPH <br /> <br />V <br /> <br />HRS. <br /> <br />I} · <br /> <br />I. 38 HRS <br />1. 53 HRS <br /> <br />)11 <br /> <br />)' <br /> <br />Figure 10: Triangular Equivalent to Routed Hydrograph <br /> <br />In figure 10. both hydrographs have the same volumes (V) and peak values <br />(Qrl). The triangular equivalent hydrograph has a slightly shorter base <br />time (Trl = 1.3B hours). <br /> <br />By forcing the routed hydrograph for the end of reach 1 back into a <br />triangular shape. we can again use worksheet W-2 by simply replacing Qp by <br />Qrl. and. Tp by Trl. It should be noted that this assumption is on the <br />nonconservative side. since the equivalent triangular hydrograph is more <br />peaked and will suffer greater reduction by the end of the second typical <br />reach. However. the effect on calculated flow depths has not been found to <br />be significant. <br /> <br />Using worksheet W-2 for typical reaches 2 and 3. and calculating flow depth <br />at the dam using manning's equation and Qp. provides the following data to <br />be used in floodplain mapping: <br /> <br />TABLE III <br />ROUTING DATA <br /> <br />LOCATION <br /> <br />O(CFS) <br /> <br />AT DlIM <br /> <br />13728 <br /> <br />Di(FT) <br />18.8 <br /> <br />L\ Th (Ims ) <br /> <br />TOTAL Th(HRS) <br /> <br />o <br /> <br />o <br /> <br />END OF REACH 1 <br /> <br />11440 <br /> <br />17.3 <br /> <br />0.21 <br /> <br />0.21 <br /> <br />END OF REACH 2 <br /> <br />6845 <br /> <br />5.4 <br /> <br />L12 <br /> <br />1.33 <br /> <br />END OF REACH 3 <br /> <br />5714 <br /> <br />8.1 <br /> <br />0.36 <br /> <br />1.69 <br /> <br />15 <br />