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where there was relatiyely high initial suspended-sediment transport, area-weighted deposition greatly exceeded area- weighted erosion during the first 3 days of the "ood (Figure Sa). The likelihood of area-weighted deposition exceeding area-weighted erosion decreased arter day 4 (Figure 5b). Area-weighted deposition never greatly exceeded area- weighted erosion upslream from the LillIe Colorado River, and a longer "ood may have been appropriate because deposition rates were low. Although the data collected by Andrews el 01. [this yolume] on which these conclusions are based are rrom only 5 sites, logistical constraints may make il prohibitive,Iy expensive for a larger number of sites to be measured on a daily basis in fUlure studies. Thus, a different research approach may be needed 10 make further progress on this issue. 6.4. Variability in Ihe Magnilude of Aggradalion Among Siles Variability in the magnitude of sand-bar change will force river managers Lo more precisely articulate their criteria for detennining Ihe "success" of any res!OraLion "ood. Large-scale measurements of sand-bar change made by Kearsley el 01. [this volume], Hazel el 01. [this yolume], Schmidl el 01. [this volume], and Thompson el 01. [1997] demonstrate that every eddy in Grand Canyon did not aggrade in the same proportion and that a few eddies experienced net erosion. These measurements document thatlhe processes measured by Alldrt!ws elal. [this volume] occurred throughoul Grand Canyon, and that the different concentrations of suspended sediment that occurred in difrerent reaches [Topping el 01., this volume] with different channel geometries [Wiele el aI., this yoIume] led to a wide range of topographic pallerns in eddies throughout Grand Canyon. Net erosion occurred in some eddies. Kearsley el 01. [this yoIume] found that 3 campsites were destroyed by the flood, and Thompson el 01. [this yolume] identified another 3 sites that had been significantly eroded by the "nod. Hazel et 01. [this volume. Table 2] estimated large standard errors of mean bar change caused by the "ood. The high-elevation part of 6 of the 35 sites that they surveyed decreased in area. Schmidt el 01. [this volume] showed that the area of signif- icant erosion exceeded the area of significant deposition at several sites. Thus. the average response of bars to the 1996 controlled "ood was high.eleyation deposition in eddies, but there were specific sites where large amounts of erosion occurred. The distinction between average and site.specitic response has led to revision of how scientists characterize bar response to changes in dam operations. Kearsley el al. SCHMIDT 337 2 .s A c 0 1.5 'w 0 W X u Q) 1:1 line :E 0 X C> 'Q; 0.5 ;: 0 0 0 . '" X 0 Q) 0 ~ jl( <t 0 (1}) 2 E B 0 g 1.5 'w e w "C Q) :E C> '~ 0.5 , '" Q) .0: o Cb o 1:1 line o o 0.2 0.4 0,6 0,8 1 Area-weighted Deposition (m) 1.2 Figure 5. Graphs showing area-weighted deposition and area- weighted erosion for each eddy measured by And~ws el a/. (this volume] for each day ror (A) .he firs. 3 days of the "ood and (8) the last 4 days of the nood. Crosses are for siles upstream from the Little Colorado River and circles are for siles funher downstream. Data above and below the I: 1 line indicate days and sites where erosion exceeded deposition or vice versa. [this volume, Figure 10], Hazel eI al. [this yoIume, Figure 2, 10], and Schmidl el 01. [this yolume, Figure 10, I I I reponed changes in eddy bars by computing frequency distributions as well as mean bar response, Managers will haye to decide if their desired end state is an average reach condition, an average reach response, or a desired change at specific sites. 6.5, Longitudinal Pal/ems of Change in Eddy Bars There is disagreement about whether the "ood caused similar responses everywhere in Grand Canyon. or if there was less deposition. and more evidence of sediment starvation, in the upstream parts of the .river sysLem. Andrews et 01, [this volume] argued Ihatlhe large volumes of sand thai accumulated, and were evacuated, frum the 5 eddies thatlhey measured demonstrate that there was surfi- .1