Laserfiche WebLink
Additional characteristics of the study reach are summarized in Table 1. Based on data <br />from the cross section surveys, the channel has an average bankfull width of 127 m, an average <br />bankfull depth of 1.90 m; and an average median grain size of 69 mm (Table 1). These values <br />correspond relatively well to the average characteristics of the 15-mile reach, determined from <br />earlier surveys of channel geometry (Pitlick et al., 1999). In comparison to the 15-mile reach as <br />a whole, the site at RM 176 is characterized by a slightly lower bankfull depth and a slightly <br />higher median grain size (Table 1.). These differences are primarily the result of an increase in <br />channel gradient within the study reach: the study reach has an average slope of 0.0020 m/m, <br />whereas the 15-mile reach has an average slope of 0.00175 m/m. <br />Table 1. General characteristics of the Colorado River at the RM 176 study site. <br /> Bankf ill Bankfull Median Grain Size, <br /> Width (m) Depth (m) D50 (mm)' <br />XSECT 1 132 1.38 60 <br />XSECT 2 110 2.15 - <br />XSECT 3 116 1.69 52 <br />XSECT 4 105 1.70 59 <br />XSECT 5 87 2.20 99 <br />XSECT 6 104 2.40 81 <br />XSECT 7 119 1.96 82 <br />XSECT 8 148 1.98 76 <br />XSECT 9 154 1.82 - <br />XSECT 10 163 1.82 67 <br />XSECT 11 163 1.80 - <br />Site average 127 1.90 69 <br />15-mile reach averaee2 134 2.54 58 <br />1. Values of D50 at cross sections 6, 7, 8, and 10, represent the average of two samples. <br />2. Averages for the 15 mile reach from Pitlick et al. (1999). <br />Sediment Transport <br />Sand and Granules: Seasonal transport of sand and granules over gravel bars and riffles <br />was monitored by installing a series of stream-bed traps at various locations. The traps consist of <br />20-cm coffee cans mounted within a piece of plastic pipe, both placed flush with the bed surface <br />16