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<br />001738 <br /> <br />15 <br /> <br />The first model simulates flow and sediment transport in individual eddies and is used to predict <br />how sandbars build under varying flow and sediment supply conditions. The second model uses <br />results from the first model to simulate sediment transport, erosion, and deposition down the <br />Colorado River channel between Lees Ferry and Phantom Ranch. When completed, this model <br />may be used to assess the effects of various dam operations on fine sediment resources in the <br />CRE, and to tailor-design any future high-flow test hydrographs (peak and duration) to maximize <br />effectiveness in bar-building response. The model will be a valuable tool to help managers <br />assess the potential effects of management decisions before implementation. <br />One of the primary recommendations of the water quality Protocol Evaluations Panel was <br />the development of numerical models of water quality dynamics within the CRE. Numerical <br />models are useful for various applications, including 1) analyzing "what if" scenarios for <br />management decisions (e.g. how would a temperature control device at GCD affect temperatures <br />at various downstream locations?), 2) interpolating both spatially and temporally between <br />collected data (i.e. filling gaps in monitoring records), and 3) isolating the effects of different <br />driving mechanisms (e.g. how do fluctuating flows affect downstream oxygen levels with all <br />other factors being equal?). Beginning in FY05, work was initiated on the development of a <br />water quality model of the Colorado River downstream of Glen Canyon Dam, and this work will <br />continue in FY06. The model is one-dimensional (streamwise) and incorporates results from a <br />previously developed ID flow model. A modular structure is being implemented so that any <br />generic source/sink term can be added to the model in order to simulate the parameter of interest. <br />The first source/sink term being added to the model is heat exchange between the river and the <br />atmosphere in order to simulate water temperature, since temperature is an important parameter <br />for many ecological processes. Future envisioned additions to the model include DO-BOD <br />relationships, nutrient transport and cycling, and linkage to the fine sediment transport model to <br />assess the effects of fine sediment on other ecosystem processes. The model will be an essential <br />tool for integrated analyses of water quality data in the context of the aquatic foodbase program. <br /> <br />Fine-Sediment and Related Shoreline Habitats <br /> <br />Fine-Sediment Storage Monitoring: Individual sand bar data collected from 1990 <br />through fall 2003, show that sand bars in the actively fluctuating zone (8,000 to 25,000 cfs), and <br />above the 25,000 cfs stage within Marble Canyon (river miles 0-61) have continued to decline <br /> <br />GCMRC FY2006 Annual Work Plan (Draft February 15,2005) <br />