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I I I I I I I I I I I I I I I I I I I 00lu;J7 4. Sed iment Yi e 1 d Sediment yield is greater than the suspended sediment load by an amount equal to the bedload transport. Almost all of the sediment derived from the Cherry Creek catchment is stored in the lake behind Cherry Creek Dam. The Corps of Engineers has measured these deposits to be 3035 acre-feet in volume deposited in 17.4 years (Stevens, 1983). A large portion of this sediment came with the June 1965 flood which also contributed an immense quantity of trees and driftwood which was subsequently burned and burried. The volume of sedi- ment is equi va 1 ent to a sediment yi e 1 d of approx imate ly 600 tons per square mile per year. The measured dry unit weight of the deposits is 60 pounds per cubic foot. For the purpose of this study, it is assumed that the sediment yield is 600 tons per square mile per year and that the amount of sediment being deposited in and immediately upstream from the Cherry Creek lake is 175 acre-feet per year (Ref. 4). Most of this is probably sand. C. Fluvial Morphology The morphology of Cherry Creek in the alluvial section upstream from Cherry Creek reservoir is the result of the water and sediment supplied to the reac h and the backwater in fl uence on the Cherry Creek dam. At the present time, the influence of the dam has not reached upstream as far as Arapahoe Road. 1. General Plan The study reach of Cherry Creek is from the County Line to Arapahoe Road. The plan view is shown in Figure-3. The location of the riverbed was traced from the I-inch equals 400-feet scale aerial photograph taken in (ktober, 1983. The river meanders through its own alluvium and terraces on a valley floor with an average width of approximately two-thirds of a mile. -15-