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4-35 <br />r 1 <br />LJ <br />The flood hazard evaluation used the flood discharge values <br />described in Table 4.5-6. The geometrics of various typical <br />channel sections were determined by actual field measurements. <br />Using standard engineering procedures (Manning's equation), <br />the hydraulic characteristics of the channel were determined. <br />Using these data, the depths and widths of floodplains of <br />various recurrence intervals were estimated, <br />waste rock disposal area. <br />The flood discharges used included the 10-year, 50-year, <br />100-year and 500-year events. In the reach of Munger Creek, <br />which is adjacent to the waste rock disposal area, the <br />drainage area is relatively constant. Therefore the dis- <br />• charge for a given recurrence interval was assumed to be the <br /> same at all cross-sections. The discharges used are shown <br />in Table 4.5-6. <br />A total of five representative channel sections were measured <br />in the field. The locations of these sections are shown in <br />Figure 4.5-6. In general, the bottom of Munger Canyon is <br />infilled with alluvium, forming a relatively flat valley <br />floor several hundred feet wide. The main channel of Munger <br />Creek is deeply incised within the area. The channel sections <br />which were measured are shown on Figures 4,5-7 and 4.5-8. These <br />sections show only that portion of the valley bottom contain- <br />ing the channel. <br />• The hydraulic characteristics of the channel sections were <br />evaluated using the Manning equation and assuming normal flow <br />