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<br />Harder's diffusion routing model. <br /> <br />Upon dev,:'lopment of a base mode ~~ that <br /> <br />accurately reflected the peak flows derived :~)~O11l the statistical anaJ.ysi.s <br /> <br />of streamflow records, Butt:onrock Reservo:L: ~')B.S inserted and its :~m~Jac.ts <br /> <br />evaluated. <br /> <br />For a detailed description of the hydrolni:;i.c analysis, the rea:ier i8 <br /> <br />referred to the Technical Addendum. <br /> <br />Hy~raulic Analysis <br /> <br />Analyses of the hydraulic characterist:~ es oj' t he stream tn t.he r;tudy area <br /> <br />were carried out to provide estimates of l:n~:: water surfac€~ elevations c.f <br /> <br />floods of the selected recurrence interval[:i, The water surface elevations <br /> <br />were computed through use of the Corps of r :q:;:Lneers' lfEC--2 step backTrlater <br /> <br />computer program (Reference 8). Cross-sect: L0I1~3 for the backwater anc:dyse.s <br /> <br />were digitized from topographic mapping of tho study reach. <br /> <br />The loea riOl' <br /> <br />of the cross-sections used in the flo(1c <br /> <br />profile computa.t ions are <br /> <br />referenced on the flood area map (Plate I) and flood profiles (Plate 21. <br /> <br />Flood elevations and discnarges for the 'C". 50-, 100-, and 50C'..year <br /> <br />events for each referenced cross.-sect:i.on aT" :i.sted in Table 3. <br /> <br />Sel ect"d <br /> <br />cross-sections within the study reach are ill,l[strated on Plate ~. <br /> <br />Channel roughness coefficients (Manni.ng', "n") for the flood profile <br /> <br />computations were assigned on the basjs o~: fteld inspection o:~ the ma.in <br /> <br />charmel and floodplain through the study ",,,,,,h. <br /> <br />The "n" valu(.~s for the <br /> <br />main channel and overbanks range from (), C13 to 0.09. <br /> <br />1\ detai led <br /> <br />description of the hydraulic analysis i. Included in the Technical <br /> <br />Addendum. <br /> <br />1.- <br />.) <br />