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Lives lost due to dam failure continued
This chart shows estimations using another Loss of Life equation. This
equation was developed by DeKay and McClelland, and looks like this:
Loss of Life = .146 - .478*[ln(population at risk)] - 1.518(warning
time)
ln is short for natural logarithm and is a function on scientific
calculators.
 An engineer might think of it like this:
L = estimated loss of life
P = population at risk
R= warning time
L = 0.146 - 0.478[ln(P) - 1.518T]
Try this equation on your calculator for some of the
incidents below. Do you get what DeKay and McClelland got?
As you can
see, this equation does not take into account the geographical surroundings of
the dam, and in this way differs from Brown and Graham's equation.
| Dam Site and Date of Failure | Population at Risk | Warning Time (in
hours) | Actual Loss of Life | Predicted Loss of Life |
| Black Hills, SD, 1972 | 17000 | <1.0 | 245 | 174 |
| Buffalo Creek, WV, 1972 | 5000 | <1.0 | 125 | 87 |
| Kansas River, KS, 1951 | 58000 | >2.0 | 11 | 0 |
| Malpasset, France, 1959 | 6000 | 0.0 | 421 | 406 |
| Teton, ID, 1976 (dam through Wilford) | 2000 | <1.5 | 7 | 25 |
| Teton, ID, 1976 (Rexburg to American
Falls) | 23000 | >1.5 | 4 | 4 |
Test Brown and Graham's equation on the previous page with some of these
incidents. How do the predictions using Brown and Graham's equation differ
from DeKay and McClelland's? How close are the predictions to the actual loss
of life?
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What other things do you think should be taken into account in these equations
for predicting loss of life due to a dam failure?
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reference: DeKay and McClelland
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