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<br />2.4 Sediment Transport <br /> <br />2.4.1 Slope Analysis <br />Figure 2.4.1 graphs stream elevation profiles for the portion of Willow Creek that was modeled <br />in HEC-RAS. A graph is presented comparing all the reaches as well as separate graphs for <br />Willow Creek, East Willow Creek, and the lower portion of West Willow Creek. Elevations <br />shown are for the bottom of the main channel and distance is in feet along the main channel. <br />Assorted cross-sections numbers from the HEC-RAS analysis are also noted for reference. It <br />should again be noted that, although surveyed, the base elevations for the cross-sections <br />upstream of the Commodore Mine on West Willow Creek were established from USGS <br />topography and are approximate. General areas of similar stream slope can be noted in the <br />profile plots. Table 2.4.1 lists average percent slopes of similar reaches. <br /> <br />Table 2.4.1. Average slopes of similar stream reaches <br /> <br />Stream Reach Cross-Sections Slope <br />Willow Creek 4.0 to 13. 7 2.09% <br /> 14. 1 to 16.0 2.01 % <br /> 20.0 to 22.0 2.94% <br />West Willow Creek 23.5 to 26.4 3.93% <br /> 27.0 to 3 1.0 5.64% <br /> 32.0 to 33.7 8.18% <br /> 34.0 to 35.2 14.71 % <br /> 38.4 to 42.0 14.96% <br /> 42.0 to 44.0 3.82% <br /> 44.0 to 45.0 7.70% <br />East Willow Creek EO.4 to E4.0 3.65% <br /> E9.0toE11.8 3.56% <br /> E14.0 to E18.0 4.55% <br /> <br />The entire study reach has a relatively high stream slope, but there are some variations. Areas of <br />similar slope are often separated by a culvert, weir, or bridge or a timber cribbed retaining wall. <br />Weirs and timber cribbings between the flume and the Commodore Mine do locally reduce <br />intermediate slopes. Some increased deposition and reduction of slope is noted before the weir <br />and two cribbings on the lower section of Willow Creek. <br /> <br />2-43 <br />