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B. Quarrv Study Site The Quarry study site is located between RM 307.6 and 308.5 and morphologically represents sub-segment B from RM 294.8 to 309.8 of segment 3, from Spring Hollow, upstream to approximately 0.8 of a mile above Red Wash. Sub-segment B exhibits the broadest flood plan anywhere on the Green River (Rose 1987). It is straight to mildly meandering with a low gradient. There are some wooded bottoms and a lot of adjacent agricultural development. There are 'several islands within the reach. The slope of the stream equals 0.00027 (Rose 1987; Figure 9). The channel stability of the Green River from RM 237 to 310 is presently in adjustment to its sediment load and current discharge patterns (Lyons, 1989; Pucherelli, 1988). A channel size increase of two percent during the high flow years of the early 1980's suggests potential for future changes within the realm of equilibrium. According to Lyons (1988), such changes are short term adjustments in the equilibrium of a stream (occurring and persisting on the order of 1 - 10 years). 1. Field Measurements Field data collection for channel geometry and hydraulics was completed throughout the 1986 and 1987 summer field seasons. On July 31, 1986, a site map was drawn and three transects identified and surveyed. The transects during the 1986 summer field season were only used for sediment sample collections. In may of 1987, four additional transects were added to the Quarry site as it was developed for PHABSIM use. On May 5, the depth and velocity distributions for each transect were recorded at a flow of 10,736 cfs. On May 7th and 29th, July 9th, and August 11th, additional WSE's were collected at each transect at flows of 9058, 5364, 2538 and 1081 cfs, respectively. On August 11, during low flow conditions, the stream was waded where possible at each transect to evaluate the predominant and surrounding substrate particle sizes. In sections of the transect too deep to wade, an oar was lowered from the front of the boat to estimate substrate types. Distances between transects were measured along the water's edge for both banks and a plot of the longitudinal profile prepared. The river at this site is generally troughlike and characterized by runs, eddies, backwaters and large sandbars (Table 18). Although, the channel is considered stable, the sandbars shift location in the stream with changes in discharge. Sand is the most common substrate with cobble along the river edges. 2. Model Calibration The output from the WSEI4S program gives an estimated WSE and discharge for each transect at measured flows (Tables 19 and 20). In this analysis, ratios between measured and predicted discharges range from 0.90 to 1.12 for 28