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<br />that the points have been reordered is <br />expected and the -25. station that should <br />be a +25. will likely never be detected. It <br />is a significant error but not significant <br />enough to be seen from normal checks on <br />output, such as a rating curve or profile <br />plots. A piot of the valley section input data <br />is an excellent data check. A separate plot <br />program is available. <br />Reach length is defined differently in <br />WSP2 than in some previously used SCS <br />computer programs. In WSP2, the hydraulic <br />length of channels and flood plains is meas- <br />ured from the section under consideration <br />to the next downstream section. <br />A few coding and keypunch errors can <br />be eliminated if optional information is <br />omitted. For example, the elevations on <br />segment boundary points can be left off if <br />the station value is unique, <br />The name of roads and r8aches should <br />contain no more than six characters be- <br />cause this is all that is retained by the <br />program. <br />Examine all WSP2 output to determine <br />the adequacy of the answers. Use USGS <br />rating curves, flood profiles, and all other <br />availabie information to check WSP2 rat- <br />ings. Pay careful attention to BPR bridge <br />head losses and to valley section ratings, <br />particularly if velocities exceed 11 ft/sec. <br />Note that a water surface reversal occurs <br />in the sample output between sections <br />92397 and 92100, This is due to a large <br />change in velocity head. When this occurs, <br />compare the input data and the physical <br />situation to determine the cause and pro- <br />ceed accordingly. <br />Always request the segment table if you <br />run seven or fewer profiles. This generates <br />no more pages of output and adds only <br />minimal cost for printing. The KD table <br /> <br />that gives values at even foot increments <br />should rarely be needed because KD <br />values at profile point elevations are pro- <br />vided in the segment table. <br /> <br />The largest single cost in the sample job <br />was to analyze the head ioss through the <br />two culverts, The following information is <br />intended to help eliminate unexpected <br />large costs for culvert analysis. The cost of <br />analyzing the head loss through a road <br />restriction with culverts depends mainly on <br />(1) the number of profiles being processed, <br />(2) the amount of head loss for each pro- <br />file, (3) the type of culvert being analyzed, <br />and (4) the number of openings of different <br />configuration. <br />On the USDA computer in Washington, <br />D.C., cost of analysis is generally 8~ per <br />foot of head loss through a box culvert. A <br />circular culvert costs about 2.5 times more <br />and a pipe arch culvert costs about 16 <br />times more to analyze than a box culvert. <br />Therefore, a job running two profiles' <br />through one circular culvert having losses <br />of about 2 feet (1st profile) and 3 feet (2nd <br />profile) would cost about 20~ (2.5 times <br />8~) per foot of head loss. The total loss is <br />5 feet, and thus the total cost would be <br />about $1. <br />If necessary, costs can be reduced by <br />converting arch culverts to rectangular cul- <br />verts of equal area, or several dissimilar <br />culverts can be run as a battery of identical <br />culverts of equal area. <br />If you are in doubt as to whether a <br />restricted opening should be analyzed as <br />a bridge or a culvert, analyze the opening <br />as a culvert. Culvert loss analysis is more <br />reliable than the BPR bridge loss analysis. <br />Therefore, if there is a choice, call the <br />opening a culvert. <br /> <br />12 <br />