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Computed wind function values for the San Diego Aqueduct. Every other point plotted for the 28-day period starting July 25, 1973 ____________________________________________________-15 13. Comparison of the modeled and observed temperatures at the downstream end of the San Diego Aqueduct during the first 4 days of the calibration period

_____-__-_-_-_ Introduction __ ________________________________ Theoretical considerations ____-_ __ _-Relative velocities of water-transported particles with differing densities ________ Shear stress as a density-segregation parameter ____ ___ ________ ____ __ Bed forms produced by flow in an alluvial channel ___ _ _ ___ __ Relation of grain entrainment to turbulence __ Summary ________________ ________ _ Experimental runs and results of sediment analysis-Hydraulic measurements _____________________ Sediment analysis __ _ _______ __ Sediment characteristics ________ __ Size analyses total bed material _________ Size analyses suspended sediment ____ Size analyses core samples ___________ Experimental results ____________________ Summary of bed form and opaque-heavymineral segregating characteristics _________ Dune bed forms (run 1) _________________ Dune bed forms (run 2) _________________ Transition bed forms (run 3) _____________

A coupled flow-temperature model has been developed and verified for a 27.9-km reach of the Chattahoochee River between Buford Dam and Norcross, Ga. Flow in this reach of the Chattahoochee is con tinuous but highly regulated by Buford Dam, a flood-control and hydroelectric facility located near Buford, Ga. Calibration and verification utilized two sets of data collected under highly unsteady discharge conditions. Existing solution techniques, with certain minor improvements, were applied to verify the existing technology of flow and transport modeling. The linear, implicit finite-difference flow model was calibrated by use of a depth profile obtained at steady low flow and unsteady flow data obtained in March 1976. During the calibration period, the model was generally able to reproduce observed stages to within 0.15 m and discharges at less than 100 m3/s, to within 5 percent. Peak discharges of about 200 m3/s were underestimated by about 20 percent. During the verification period, October 1975, the flow model reproduced observed stage changes to within about 0.15 m, and its timing and overall performance was considered to be very good. Dye was added to the upstream end of the river reach at a constant rate while the river flow was highly unsteady. The numerical solution of either the conservative or nonconservative form of the masstransport equation did an excellent job of simulating the observed concentrations of dye in the river. The temperature model was capable of predicting temperature changes through this reach of as large as 5.8°C with a RMS (rootmean-square) error of 0.32°C in October 1975 and 0.20°C in March 1976. Hydropulsation has a significant effect on the water temperature below Buford Dam. These effects are very complicated because they are quite dependent on the timing of the release with respect to both the time of day and past releases.