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<br />r <br /> <br />I <br /> <br />001548 <br /> <br />" <br /> <br />; <br /> <br />E. Determine the actual stream classification based on measured data <br />and field observations. <br /> <br />F. Computed sediment load based on DH-48 and Helley-Smith samples. <br /> <br />IV. CHANNEL STABILITY ANALYSIS <br /> <br />A. Develop flow-duration curve and mean annual hydrographs from USFS <br />base station data as used in the original quantifications or <br />develop new flow-duration curves and mean annual hydrographs from <br />available data using standard engineering practices. <br /> <br />B. Evaluate hydraulic conditions (velocity, depth, topwidth) for range <br />of flows indicated by the flow-duration curve. Include flows <br />through at least the bankfull discharge. <br /> <br />I. Use representative hydraulic geometry relations. <br />2. Use friction slope (S) from measured water-surface profiles. <br />3. Use Manning equation (V = 1~49 R2/3SI/2) for flat (C-type) <br /> <br /> <br />streams and_Chezy equation V = CjRS with C = ~ j9 for <br /> <br />streams. ~ values for steep, cobble- and boulder-bed <br /> <br />streams can be estimated from SLA's previous work. <br /> <br />C. Estimate incipient particle size and percent of bed material that <br />can be moved for the range of flows considered in the hydraul ic <br />analysis using Shields criteria (Simons & Senturk, 1976). This <br />approach, the incipient particles size (maximum size particle that <br />can be moved by the flow) is estimated by the relation <br /> <br />10 <br />Di= F*e(S-I); where <br /> <br />Di = incipient size, <br />10 = bed shear stress, <br />e = density of water, <br />S = specific gravity of sediment, and <br />F* = dimensionless Shields parameter. <br /> <br />Due to uncertainty inherent in selecting an appropriate value for <br />the Shields parameter, the Phase II procedure may require a <br />sensitivity analysis to determine the impact of using different <br />values. <br /> <br />D. Develop sediment-transport capacity relationships by particle size <br />fraction using appropriate bed-load and suspended bed-material load <br />relationships. (SLA recommends use of the Meyer-Peter, Muller/ <br />Einstein approach.) <br />