In the output for TEST 1C, notice that for Q = 100, the panel between stations
50.0 and 80.0 has a calculated n-value of 0.0305. The comment column for this
panel shows "R S", indicating rough flow and that the Strickler method was
used. The input data requested Keulegan, but, NOTE, SAM will not apply
Keulegan if ks/R< 3 . It automatically substitutes Strickler.
The Normal depth Table 8-1 and the Flow Distribution Table 8-2 are repeated
for every discharge prescribed on the QW-record. The composite hydraulic
parameters for each discharge are highlighted between the flow distribution
tables, with "****". In the example output included in this chapter, the
printout for discharges 4 and 5 have been omitted.
Hydraulic Parameters for Sediment Transport Table The results printed
in Table 8-4 are representative hydraulic parameters for making sediment
transport calculations. The effective velocity, depth, width and slope are
calculated for both overbanks and the channel. EFFECTIVE WIDTH, EFW, and
EFFECTIVE DEPTH, EFD are defined by the following equations:
Σ d i Ai d i 2/3
EFD =
Σ Ai d i 2/3
Σ Ai d i 2/3
EFW =
EFD 5 / 3
where:
Ai = flow area of each trapezoidal element
di = average water depth of each trapezoidal element
Equivalent Hydraulic Properties for overbanks and channel Flow
distribution and conveyance-weighted hydraulic parameters are calculated for the
overbanks and channel and listed in Table 8-5. The water-surface elevation that
was calculated using the specified compositing method determines channel and
overbank subareas and wetted perimeters. Conveyance for each subarea is
calculated using the Chezy equation and conveyance weighted discharges
determined. Using the area, wetted perimeter, discharge, and slope for the three
subareas, a composite n value is calculated for the channel and both overbanks.
Plotting The following hydraulic output plots should be available: stage
versus n-value; stage versus average velocity in cross section; stage versus
effective velocity; stage versus discharge; stage versus width; stage versus
effective width; stage versus hydraulic radius; cross section geometry;
and, slope versus width.
92
Chapter 6
Input Requirements and Program Output for SAM.hyd
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