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I I I I I I I I I I I I I I I I I I I 15 River near the Colorado-Utah state line, near the downstream end of the study area. The Palisade gauge is at the head of the Grand Valley above the confluence of the Gunnison River, and the state line gauge is in Ruby- Horsethief Canyon (Fig. 1). The flows of 1993 were above average. Discharge began to increase in late April, flows increased sharply in the beginning of May, and the peak flow of 1,250 cms (44,300 cfs) occurred on May 28 which has a return period of approximately 6 years (Fig. 8). Runoff continued into the middle of August. In contrast, the flows of 1994 were below average, with a return period of the peak flow of only 1.16 at the state line gauge. Flows did not increase substantially until the second week in May, flows peaked at 370 cms (13,100 cfs) on June 2, and runoff ended by the first week in July. Flows at the Palisade gauge show similar trends and recurrence intervals, but are of a smaller magnitude since they are upstream of the Gunnison River. The combined effect of both the difference in magnitude and duration of flow is evident in the mean annual discharge of the river in the two years. In the 1993 the mean annual discharge was 240 cms (8,490 cfs), and in 1994 it was only 130 cms (4,590 cfs). The different flow magnitudes of these two years were ideal for our studies of the affects of flow on channel morphology and sediment transport. It allowed us to document stage-discharge relationships near bankfull discharge in 1993, and to measure the effects of high and low flow years on backwater morphology.