the water surface), i.e., the 85,000 cfs discharge fills the 28 ft of depth prescribed
by the bank heights, causing the high flow channel to gain width. Each bottom
width given in Table 5-1 is the width of that channel, from toe of slope to toe of
slope, as shown in Figure 6.9.
Occassionally the following warning message will appear:
ABNORMAL TERMINATION OF WIDTH CALCULATION.
SUCCESSIVE ITERATIONS ARE NOT IMPROVING THE CONVERGENCE.
The program will then print values on the "****" lines anyway. The warning
indicates problems encountered when trying to converge on an appropriate width.
To check the answer for reasonableness, use the calculated bottom width as input
to the water surface elevation calculations. If the water surface then calculated is
close to that the bottom width calculations printed, then the answer is reasonable.
TABLE
5-1.
CALCULATE BOTTOM WIDTH;
COMPOSITE PROPERTIES BY ALPHA METHOD.
**** N
Q
WS
BOTTOM
R
SLOPE
n
VEL
FROUDE
SHEAR
ELEV
WIDTH
Value
NUMBER
STRESS
CFS
FT
FT
FT
ft/ft
FPS
#/SF
**** 1
600.
3.00
16.5
2.74 0.003000 0.0203
7.83
0.85
0.51
**** 2
12000.
13.00
41.1
10.46 0.003000 0.0254
15.23
0.84
1.96
**** 3
85000.
28.00
145.2
20.32 0.003000 0.0258
23.34
0.91
3.80
Energy Slope Calculation: Input and Output
Energy slope can be determined with this option, where slope becomes the
dependant variable in the Manning equation:
S = f ( W, Q, n, D, z, S)
Geometry, roughness, compositing, and plotting are handled the same as
described for the normal depth calculations. Choose "Energy Slope" as the
"Variable to Calculate."
Sample Input Data
The following example shows input data when calculating energy slope.
Notice that it is the same as shown for Normal Depth except that the WS-record
is present and the ES-record is missing. The missing ES-record tells SAM to
calculate the slope.
96
Chapter 6
Input Requirements and Program Output for SAM.hyd
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