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<br />N <br />~ evaluating the effect of debris fl~ws in tributary canyons on sand <br />~,.J bars; (4) determining the significance of ground-water movement <br />C.~) into and out of sand bars on the stability of the bars; and (5) <br />developing predictive models for sand bar evolution. Activities in <br />these el,ements through 1992 included (1) seismic surveys, drilling, <br />and bathymetric surveys to determine the aerial extent and <br />thickness of sand deposits; (2) determining the depositional <br />history of several bars by examination of internal sedimentary <br />features; (31 monitoring several sand bars downstream from recent <br />debris flows; (4) instrumentation and monitoring instrumentation to <br />measure ground-water flow and slope movement at three sites; and <br />(5) development and initial verification with laboratory data of a <br />physically-based model for eddy flow. <br /> <br />2. Sediment Transport Project. The objective of this project <br />is to develop sand-transport models for the canyon that will <br />accurately reproduce all pertinent processes and enable prediction <br />of the effectr of various dam operation scenarios on transpo~t of <br />sand. Models will provide the boundary conditions for eddy models <br />of the 'Beach Evolution Project. Three models are requirE!d; a <br />surface-water flow model, a model for transport of conservative <br />solutes, and a sand-transport model, Prediction of sand in the <br />canyon due to dam operations also required the prediction of <br />sediment inputs from tributaries. Activities through 1992 included <br />(1) measuring channel geometry and bed roughness in sel ected <br />reaches; (21 measuring mass transport at two flow conditions using <br />a dye tracer; (31 installing a dense network of stage gages (about <br />501, and monitoring along the 300-mile reach; (41 measuring <br />detailecl. suspended-sediment fields at a gaged station for a variety <br />of flow conditions; and (51 initial development of one unsteady- <br />flow model for the prediction of discharge throughout the study <br />reach. <br /> <br />3. Lake Powell Water Quality Project. A report on data <br />collectE!d in 1991 was prepared in 1992, and a study of planktonic <br />production in Lake Powell was planned in 1992 for initiation in <br />FY93. <br /> <br />4. Hydrologic Data and Data-Base Management. This project <br />invol ves the co 11 ection of stage, discharge, and some physical <br />characteristics of water at six Colorado River mainstem gaging <br />stations and five gaging stations on tributaries of the Colorado <br />River between Glen Canyon Dam and Lake Mead. Also, data from a <br />network of stage sensors are collected and stored. All data are <br />stored in a computer data base available to users of hydrologic <br />data, <br /> <br />, j ~ <br /> <br />';.. ,;;>,- <br /> <br />~. ~""- -.'..., <br /> <br />~,~,J <br />