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<br />14 <br /> <br /> <br />OiJ2464 <br /> <br />12, 1990, and November 2,2001. Kaplinski et a1. (1995) reported that the area and <br />volume of sand above the stage of 142 m3/s did not change significantly between 1990 <br />and 1995. In their analysis of erosion and deposition during the 1996 controlled flood, <br />Hazel et a1. (1999) documented no significant topographic changes above the 566 m3/s <br />stage and a 7% increase in area and 19% increase in volume above the 142 m3/s stage at <br />this one site, These areas and volumes of deposition are very small in comparison to the <br />average response measured at sites in Marble Canyon and Grand Canyon (Schmidt et aI., <br />2002). <br /> <br />METHODS <br /> <br />Measurements of tbe Bed <br /> <br />Bureau of Reclamation Cross-sections <br />In 1956, the U.S. Bureau of Reclamation established 22 channel cross-sections on <br />the Colorado River between the Glen Canyon damsite and the Paria riffle, just <br />downstream from Lees Ferry (Figure 1). A subset of these cross-sections was resurveyed <br />in 1959, 1965, 1975, 1983, and 1990 (Table 1). Ten cross-sections were selected as <br />monitoring sites following the 1956 survey (Pemberton, 1976), and all of these were <br />measured in all of the years listed above. The Grand Canyon Monitoring and Research <br />Center (GCMRC) resurveyed nearly all of the cross-sections that had been established in <br />1956. Cross-sections R-O to R-13 were surveyed January 24-27, 2000, and R-15 to R-20 <br />were surveyed May 10-11,2000. R-3 could not be located, and R-14 was not surveyed. <br />Ground topography along the cross-sections was surveyed using electronic total stations, <br />and bathymetry along the cross-sections was measured with a boat-mounted SONAR. <br />Positions were surveyed and are reported in Arizona State Plane Coordinates, central <br />zone. Elevations are in meters above sea level (NVGD1929). The minimum bed <br />elevations are listed in Appendix B. <br />The cross-sections were classified by occurrence in riffle or pool channel type. <br />These channel types were identified in the field and by inspection of the longitudinal <br />profile and cross-section plots. Riffles were identified as segments with below average <br />