Jacob H. Douma
river's discharge capacity. If the levees are not high enough, they will be overtopped
because the tides will keep the water from going out of the river.
So those are the problems that this committee looked at all the time?
Yes.
A:
It wasn't concerned with high-velocity flows, open channels, and reinforced
or rock-lined channels. However, it was concerned about tidal flows that eroded
beaches.
So you've worked very closely, then, with both the Beach Erosion Board and its
successor, CERC?
A:
That's right. That's why they had members on that committee, too.
Apparently, the whole coastal engineering business is very difficult because of the way the
sands move around.
A:
Yes. It's really more difficult than open channel hydraulics because you can put your
finger on and more easily control the flow in an open channel not subject to tides.
What were some of the more important problems that the committee looked at and
solutions that were recommended?
A:
One project that the committee got very much interested in was the San Francisco Bay.
Tests were being made in a model of the Bay to determine water levels during floods when
rivers discharged large flood flows into the San Francisco Bay, especially in the Oakland
part of the Bay. The storm tides and waves coming in through the Golden Gate had an
effect on tidal flows in the Bay. The model would indicate what improvements to
construct to prevent yacht harbors from having problems due to the tidal flows. In the
lower Mississippi River, high levees go beyond the Head of Passes, and the height of those
levees is determined by river channel flood flows and the effect of tides.
The general overall thing that the Committee on Tidal Hydraulics did that hadn't been
done before was to identify problems and develop theoretical ways of computing what
would happen for various combinations of tides and river flows. Those weren't available
before. There was very little in the literature about tidal hydraulics before this Committee
on Tidal Hydraulics was established. It published many report that identified a lot of the
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