FLOOD08875

• County: Boulder
• Basin: South Platte
• Title: Analysis of a High Hazard Flood Zone
• Date: 10/1/1987
• Prepared For: Boulder
• Prepared By: David Love & Associates
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Product Number
Of prime interest in this analysis is the "product number", or that combination of average
velocity (V) and Flood depth (d) which creates instability under given conditions. The product
number (PN) is defmed as:

Figure 9 Table 4

The combinations of velocity and depth, detennined herein to be hazardous, were used to produce
plots of the depth versus product number for both slippage and toppling hazards (Figures 9 and
10). These are shown superimposed on their respective hazard curves. For example, referring to
the slippage resultant product number (Figure 9), a velocity of 3.15 fps produces hazard at a depth
of 2 feet as discussed earlier (fable I). Thus the product number at 2 feet is 2 x 3.15 or 6.30

Toppling Hazard
Iknth Product Number
0.4 6.08
0.6 5.90
0.8 5.71
1.0 5.52
1.2 5.33
1.4 5.12
1.6 4.91
1.8 4.68
2.0 4.45
2.2 4.20
2.4 3.94
2.6 3.66
2.8 3.35
3.0 3.01
3.2 2.63
3.4 2.19
3.6 1.62
3.8 0.70

V 10

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1

o
r

P
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d

,

V 10

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o
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P
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d

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PN = V x d

Slippage Hazard
Product Number

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:0:
..........".........\.........................................................."...............................................
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:0:

.x- 511ppoge
Prod. ' (5lipp.)

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2
Depth

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4

Toppling Hazard
Product Number

................~...... ............................... ................ :: ::::~j:g(TOPp.)

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5

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-.-.....-..- _...........~~--~_. .._---~~~.-.._-_. --.
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Depth

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4

Figure 10

.. 10-

Slippage Hazard
Oenlh ProdUCf Number
0.43.84
0.6 4.57
0.8 5.11
1.0 5.52
1.2 5.83
1.4 6.06
1.6 6.21
1.8 6.28
2.0 6.29
2.2 6.23
2.4 6.10
2.6 5.89
2.8 5.60
3.0 5.22
3.2 4.71
3.4 4.03
3.6 3.08
3.8 1.37

Table 5