FLOOD02234

• County: Statewide
• Basin: Statewide
• Title: Hydrologic Aspects of Project Planning
• Date: 3/7/1972
• Prepared For: US
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

Although technology is definitely changing in fields such as hydro-
logic engineering, and despite the fact that these changes are probably
occurring at least as fast as the requirements for planning studies are
changing, it is worthwhile to examine the question of whether technological
changes are really responsive to the changes in requirements or whether
they are merely changes which produce the same old solutions at a lower
cost or in a shorter time. For if the latter is true, there is undoubt-
edly a limit to the effort which sould be devoted to producing this type
of change. Although efficiency is certainly a worthwhile objective in
some cases, there usually comes a time when additional efficiency is not
only not worthwhile but also counterproductive. That is, it is not only
futile to build a better mousetrap if mice are no longer a problem, but
it is also wasteful to devote resources to mousetrap improvement if
cockroaches are the cause for concern.

HYDROLOGIC ENGINEERING TECHNIQUES

In general the types of hydrologic engineering methods used in conjunc-
tion with planning studies can be classified in three categories according
to the objective of the hydrologic investigation: development and analysis
of basic hydrologic data; development and analysis of criteria and project
features based on hydrologic variables; and analysis of effects of hydro-
logic variations on alternative plans of development. The first category
includes such hydrologic investigations as streamflow frequency analysis,
regional correlation studies, estimation of flows from ungaged areas, and
streamflow simulation. The second category includes investigations such
as unit hydrograph and loss rate determinations, computations of hypothe-
tical floods, and some types of channel and reservoir routing studies.
The third category consists primarily of various types of hydrologic simu-
lations such as reservoir operation studies, water surface profile
determinations, and flood hydrograph routing and combining.

In most instances hydrologic engineers have proceeded, more or less
independently, to improve existing techniques or to develop new techniques
in the first two categories without much consultation with other technical
specialists. The rationale for this has been that the hydrologic engineer
is, in general, the direct user of the output from the techniques. Conse-
quently, he is the person most qualified to assess both what is available
as input and what is required as output. To the extent that he is cognizant
of the ultimate use of the results of his study and the effect that this
use should have on the techniques employed, there is no question that he is
solely qualified to develop or select the proper technique for use in either'
of the first two categories. '

4