Water Resources: Hydraulics and Hydrology
Q ..
But the Corps went then to its National Probable Flood.
A
I am not familiar with that. We had the Standard Project Flood to serve some other
purposes, mostly with deciding on the degree of protection that could be provided.
The Standard Project Floods you tried to protect against when justified.
But Cochran developed this concept of a Standard Project Flood which often was
half as large as the probable maximum flood. It was used for functional design of
a project. The idea was to use it as a rating basis. In other words, your project still
might only provide protection against 75 percent of the Standard Project Flood, but
it was an index to work against for actual protection or whatever you were trying to
accomplish.
Q ..
But the spillway would be designed for what, the probable maximum flood, which
was a different criteria then.
A ..
Yes. It was to save the dam from failing. That's what it was for. As time went on,
there was a congressional action, the Corps was to evaluate the safety of all of the
dams in the country. They started working with the states. This was after my time.
I've got one paper there which I though would be a big use in it, but they took
another channel, another approach to determining what the standard, what the
spillway design criteria would be.
But they did develop the idea that if there's a dam where it's failure wouldn't cause
any appreciable damage downstream, well then you don't h a v e to design for the
probable maximum flood, although I don't think there are very many dams in that
category. You never know. There's somebody down there camping, or driving
along a road or something. Particularly in the private sector and the states, they set
up some standards where the Standard Project Flood would be suitable for the
spillway design and not the probable maximum flood.
Q ..
Well, I understand that's sort of what TVA does.
They use the Standard Project
Flood as the
A
Well, I don't think they would. I think they define it differently. I don't think they
would argue that the Corps' Standard Project Flood would be adequate for a
spillway design. I don't think they would get themselves in that box. I think they
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