FLOOD05043

• County: Statewide
• Basin: Statewide
• Title: Dimensionless Graphs of Floods from Ruptured Dams
• Date: 1/1/1974
• Prepared For: US
• Prepared By: COE
• Floodplain - Doc Type: Educational/Technical/Reference Information

Integration of Eq. 15 and solution for tw yields
tw = v (Xw, 10, M, C)

(16)

The left-hand side of each of Eqs. 13, 14 and 16, constituting the practically
important dam-break flood variables, can be plotted versus x with C as a
parameter in one sheet of paper for given values of 1 and M. In the
triangular cross-section, defined for M = 1, C is no Yonger a parameter
because the hydraulic radius through which Centers Eqs. 4 is a linear
function of y and thus C is eliminated. In this case fo may be used as a
parameter to distinguish curves in the same plot.

2. Range of Parameters

For the preparation of dimensionless graphs of the dam-break flood
variables actual conditions are assumed to vary between the following
extremes:

.

Condition

Minimum value

l>'.aximlJ!1 value

Water depth behind dam, Yo 10 m (32.8 ft) 200 m (656 ft)
Channel bottom slope, SQ 0.0005 0.010
Manning roughness coefffcient, n 0.015 0.150
Cross-section exponent, ~ _ 0 1
Relative top width,_C = Bc/Yn 1 50
Froude number fo = Vol,l 9 Yo 0.025 5

The extreme values of fo are determined from the combinations of Yo, So,
n, M and C leading to extreme values of Yo.

3. Data Acquisition

For preparing the dimensionless flood graphs, data were obtained for
the following values of the parameters 10, M and C in the above listed
range:

1F0 = 0.025
M = 0
C = 1

0.10
0.50
2

0.50 1 2
1
5 10 50

5

The wave-front location at any time is given directly by the solution.
The value of YM in each stage hydrograph is determined as the maximum of
discrete values of y obtained in the course of the solution. The latter
are close enough to insure practically insignificant deviation from the
true maximum. The time at which Yr1 occurs is the value of 1+1.

The solution progressed
obtained for a cross-section
Minimum value of m is 1000.
peak, then

in time until values of YM and tM were
at 2 distance at least mYo below the dam.
If xM designates the abscissa of a flood

.

6