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10 For the Green, the geometric response to water and sediment variability was estimated by Andrews [3] in his prediction of equilibrium channel width. Figure 2 illustrates his equilibrium width of 524 feet for the upper study reach and 450 feet for the lower study reach in comparison to the trends reported by Pucherelli ([4] and [5]). These widths were computed from hydraulic geometry relationships developed by Leopold and Maddock [10] relating width and bankfull discharge. Andrews [11] demonstrated a marked similarity between bankfull discharge and effective discharge for several streams in the Yampa River Basin and he extrapolated this finding to the Green for development of the equilibrium channel widths reported in [3]• His com- puted effective flow of 11,500 ft3/s should apply to the portion of the upper study reach upstream of the Duchesne. The average channel width reported by Pucherelli [4] for this portion of the upper study reach for 1974 is 665 feet; 27 percent greater than Andrews' pre- dicted equilibrium width based on 11,500 ft /s. The channel width in 1974 appears to be a new equilibrium as a subsequent measurement in 1978 yielded an estimate that was only slightly larger than that of 1974. The flow-duration curve for the 1974-1978 period is similar to the flow-duration curve for 1964-1974. If channel width had not reached a new equilibrium in 1974, narrowing should have continued to occur and be evident on the 1978 pho- tography. In the regime relationships proposed by Leopold and Maddock and used by Andrews to compute the equilibrium channel width; w=aQeb where: w = width Qe = effective flow a,b = numerical coefficient and exponent the adjustments in such factors as channel slope, bed-material composition, and suspended sediment concentration to changes in hydrology and sediment supply are reflected in the numerical coefficient and exponent, a and b. These regime relationships provide a simplified quantification of channel characteristics for channels known to be in quasi -equilibrium. Andrews used this width-discharge relationship to suggest that channel response of the Green to Flaming Gorge may not be complete at the present time and that a cen- tury or more may be required before a new equilibrium, in terms of channel width, is established. Andrews assumed that the coefficient a and exponent b in the equation remained constant for different periods of quasi-equilibrium for the gauged locations. Using Andrews' estimates of effective flow for the Jensen and Green River gauges and the measurements of average channel width reported by Andrews [3] and Pucherelli [4] and [5], the following estimates of the coefficient a were derived when b is held constant at 0.5: