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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 FailurePopulation at RiskWarning Time (in hours)Actual Loss of LifePredicted Loss of Life
Black Hills, SD, 197217000<1.0245174
Buffalo Creek, WV, 19725000<1.012587
Kansas River, KS, 195158000>2.0110
Malpasset, France, 195960000.0421406
Teton, ID, 1976 (dam through Wilford)2000<1.5725
Teton, ID, 1976 (Rexburg to American Falls)23000>1.544


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?

What other things do you think should be taken into account in these equations for predicting loss of life due to a dam failure?



reference: DeKay and McClelland


Brown and Graham Examples of failures