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River decreased, bUI by a smaller fraclion than Ihe decreasc in sediment supply. In the posl-d<lm system, the majority of sediment supplied 10 lhe Colorado River in Marble and Grand Canyons comes from Ihe Paria and Lillie Colorado rivers, Large inpuls of sediment from the Paria River occur during high-discharge, shOrl-duralion Roods thatlypically occur in July through October, whereas large inputs of sediment from the Lillie Colorado River occur during Roods that lypically occur both in July lhrough October and in January through early April. High mainstem Rows in the post-dam system, however, do not necessarily coincide with these tributary sediment-supplying events, because high mainslem Rows are produced by tbe dam operators to generate power and maintain reservoir levels. Therefore, as with pre-dam conditions, there may be still a mismatch in the timing of large sediment inputs to the system relative to the timing of high Rows in the mainSlem. Thus, during high Rows in the post-dam river, we expect suspended-sediment concentrations to decrease with time, and grain sizes. in both suspension and on the bed, to coarsen with time in response to depletion of fine sediment in the system [Rubill el ai" 1998], just as during pre-dam snowmelt Roods. During lhe 1996 controlled Rood [Schmidl el al" this volume], as parl of a larger USGS dala collection effort, we set out \0 improve our understanding of the intricate linkage between flow, sediment supply, sediment transport, and bed morphology, To accomplish this goal, we focused on two major objectives, First, we monitored bathymetry during the Rood at both a main channel location and in a typical laleral separation eddy to monitor the effect of the Rood on the bed morphology, Second, and the subject of this paper, we documented the linkages between the grain-size distri- bution on lhe bed of the channel, the concentration and grain-size distribution of suspended sediment, and the grain-size distribution of deposits produced in depositional regions (primarily in eddies), In doing so, we focused on measuring bOlh concentrations and grain-size distributions of suspended sediment with sufficient temporal resolution (0 provide insights into the issue of supply limitation. 3, FIELD OBSERVATIONS DURING THE 1996 CONTROLLED FLOOD To study the linkage between the suspended sedimenl and bed of the Colorado RIVer during a flood, we designed a 9-day measurement program to monitor the suspended sediment, bed sedimenl, flow velocity, water-surface slope, and bed lOpography al bOlh a main channel local ion and in a lypical lateral-recirculation eddy during Ihe 1996 flood experiment. This chapter presents mainly (he depth~ TOPPING ET AL. 73 integrated suspended-sediment and bed-sediment data that we collected at the 2 sites during the \996 controlled 1I00d, The main.channel site chosen for this work. was (he reach at the USGS gage at river mile 87.4, This gage is officially designated as "Colorado River near Grand Canyon, Arizona, station number 09402500" and is referred to herein as the Grand Canyon gage. The Grand Canyon gage reach was chosen both because of its key location in upper Grand Canyon and also because of its wealth of USGS Row, suspended-sediment, bcd-sediment, and bcd-topographic data that span the period from November 1923 to lhe present. The eddy site chosen for this work was 56-km downstream of the Grand Canyon gage at river mile 122 at the mouth of Hundred Twenty-two Mile Creek (herein referred to as the 122-Mile eddy site), The 122-Mile eddy site was chosen both because it had a large eddy in which topographic changes in the bed during the Rood could be readily detected and also because it had a history of prior sedimentologic investigations, Other suspended-sedimeOl dala presented in this chapter were also collecled by the USGS at 2 other gages on the Colorado River, The first of these gages is at river mile 61,0, 42 km upstream of the Grand Canyon gage and at the downstream end of Marble Canyon; this gage is officially designated as the "Colorado Ri ver above the mouth of the Lillie Colorado River near Desert View, Arizona, station number 0938100" and is herein referred to as the above LCR gage, The second of these gages is at ri ver mile 166,1, downstream of the 122-Mile eddy site; this gage is officially designated as "Colorado River above National Canyon near Supai, Arizona, Slation number 09404120" and is referred to herein as the National Canyon gage, As measured at the Grand Canyon gage, the controlled- flood experiment consisted of three days of a steady 238 mlts discharge followed by an increase over 5.75 hrs to a discharge of 1290 mlts. This high discharge was constaOl for 7 days and then decreased over 3,2 days back to a steady discharge of 238 m3ts, In this paper, the day prior to Ihe arrival of the Rood is referred to as "day -I", Ihe seven days of 1290 m)ts discharge are referred to as "days 1-7", and the first day of the recessional limb of the flood is referred to as "day +''', 4, METHODS 4, /. Gralld CallyolI Gage Reach To monilOr the suspended sediment, we colle.:ted samples from the USGS cableway at the Grand Canyon gage (Figure 1) using both a P-6\ sampler and a bag sampler equipped with a D-77 sampler head (Edwards alld