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<br />According to the FIS te){t, the cross section geometry <br />was digitized from the 1982 aerial photography. This method <br />did not include any of the channel ':;reometry below the water <br />surface and the water surface was used as thE~ channel bed. <br />To account for the lesser HEC-2 model channel capacity, the <br />10-, 50-, 100- and 500-year discharges used in the FIS HEC-2 <br />files were adjusted by subtracting 't:he White River discharge <br />on the date of the photographY, which was 2300 cfs. <br /> <br />The stream channel reach lengths used fClr the FIS follow <br />the channel centerline, including bends. To get the <br />cumulative channel distance from the original HEC-2 data to <br />agree with the stream stationing on the work map, a <br />correction of 2400 feet needed to be added to the HEC-2 <br />cumulative distances. The stream stationing in the published <br />FIS flood water surface profiles differs from that on the <br />work map. <br /> <br />The roughness values used for the White River (Mannings <br />"n") were 0.04 for the channel and 0.06 for the overbanks. <br />It is not known if any data was used to calibrate the <br />roughness values. <br /> <br />The White River starting wa-ter surface e!levations were <br />at normal depth based on the slope-area method. <br /> <br />Two bridges were modeled in thE~ FIS HEC-'2 file. The <br />Highway 64 and White Avenue bridges were modeled using the <br />HEC-2 Special Bridge method. <br /> <br />The hydraulic effect of the levee at the, filtration <br />plant on the left bank conveyance was include,d in the <br />original model. The geometry of cross sections in this area <br />were set with no conveyance area available landward of the <br />levee below the levee top elevation.. <br /> <br />The FIS hydraulic analysis did not include any ice <br />effects. <br /> <br />HEC-2 INPUT FILES <br /> <br />Each of the HEC-2 files used in the Rangrely Section 22 <br />file is described in detail below. The HEC-2 input and <br />output for each file are included as an attachment to this <br />report and are also furnished on a diskette. The 10-, 50-, <br />100- and 500-year water surface profiles werE! plotted for <br />each file. The profile plots for the section 22 study reach <br />are attached. <br />