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<br />flow, the total loss of energy by resistance will be somewhat <br />greater with the steeper and then flatter slope because <br />a lesser depth is produced over a greater portion of the <br />barrel length. This increased loss due to resistance will <br />be small, however, as will the reduction in outlet velocity. <br />Formation of a hydraulic jump in the lower barrel is rare, <br />as the downstream depth required to force a jump will seldom <br />be encountered. If this type of design is attempted, water <br />surface profile calculations must be made to insure that <br />the hydraulic jump relationship is fulfilled. <br /> <br />For culverts on slopes greater than critical, rougher material <br />will cause greater depth of flow and less velocity in equal <br />size pipes. Velocity varies inversely with resistance; <br />therefore, using a corrugated metal pipe instead of a con- <br />crete pipe will reduce velocity approximately 40 percent, <br />and substitution of a structural plate c.m. pipe for concrete <br />will result in about 50 percent reduction in velocity. <br />Barrel resistance is obviously an important factor in <br />reducing velocity at the outlets of culverts on steep <br />slopes. Chapter VII contains detailed discussion and specific <br />design information for increasing barrel resistance. <br /> <br />III-I. <br /> <br />Federal Highway Administration, DESIGN CHARTS FOR <br />OPEN-CHANNEL FLOW, U.S. Government Printing Office, <br />Washington, D.C., 1961, 105 pp. (Hydraulic Design <br />Series NO.3). <br /> <br />! .III-2. <br /> <br />Simons, D. B., Stevens, M. A., Watts, F. J., FLOOD <br />PROTECTION AT CULVERT OUTLETS, Colorado State <br />University, Fort Collins, Colorado, CER 69-70 <br />DBS-MAS-FJW4, 1970. <br /> <br />III-3. <br /> <br />U.S. Department of the Interior, Bureau of Reclamation, <br />DESIGN OF SMALL CANAL STRUCTURES, 1974, pp. 127-130. <br /> <br />III-5 <br />