Horizontal and vertical controls generated by
land (geodetic) surveys provide coordinated
position data for all surveyors. It is therefore
necessary that these types of surveys use first-
order and second-order accuracies.
HYDROGRAPHIC SURVEYS are made to
acquire data required to chart and/or map
shorelines and bottom depths of streams, rivers,
lakes, reservoirs, and other larger bodies of water.
This type of survey is also of general importance
to navigation and to development of water
resources for flood control, irrigation, electrical
power, and water supply.
As in other special surveys, several different
types of electronic and radio-acoustical instru-
ments are used in hydrographic surveys. These
special devices are commonly used in determining
water depths and location of objects on the
bottom by a method called taking SOUNDINGS.
Soundings are taken by measuring the time
required for sound to travel downward and be
reflected back to a receiver aboard a vessel.
TYPES OF SURVEYING
The practice of surveying actually boils down
to fieldwork and office work. The FIELDWORK
consists of taking measurements, collecting
engineering data, and testing materials. The
OFFICE WORK includes taking care of the
computation and drawing the necessary informa-
tion for the purpose of the survey.
FIELDWORK is of primary importance in all
types of surveys. To be a skilled surveyor, you
must spend a certain amount of time in the field
to acquire needed experience. The study of this
training manual will enable you to understand the
underlying theory of surveying, the instruments
and their uses, and the surveying methods.
However, a high degree of proficiency in actual
surveying, as in other professions, depends largely
upon the duration, extent, and variation of your
You should develop the habit of STUDYING
the problem thoroughly before going into the
field, You should know exactly what is to be done;
how you will do it; why you prefer a certain
approach over other possible solutions; and what
instruments and materials you will need to
accomplish the project.
It is essential that you develop SPEED
and CONSISTENT ACCURACY in all your
fieldwork. This means that you will need practice
in handling the instruments, taking observations
and keeping field notes, and planning systematic
It is important that you also develop the habit
of CORRECTNESS. You should not accept any
measurement as correct without verification.
Verification, as much as possible, should be
different from the original method used in
measurement. The precision of measurement must
be consistent with the accepted standard for a
particular purpose of the survey.
Fieldwork also includes adjusting the instru-
ments and caring for field equipment. Do not
attempt to adjust any instrument unless you
understand the workings or functions of its parts.
Adjustment of instruments in the early stages of
your career requires close supervision from a
Collection of Engineering Data
The collection of ENGINEERING DATA is
a part of SEABEE surveying. Engineering data
is actually any information that is essential for
efficient construction. Most of your fieldwork,
such as running a traverse, leveling, and determin-
ing cuts and fills, may be classified under
this category. However, compiling these field
measurements and converting them into a com-
mon medium that will be of value to the engineer
requires skill that can only be attained through
long experience. Although the planning and
organization will generally be handled by the
engineering officer or by a senior EA, the actual
collection of engineering data will generally be
delegated to you; hence, it is to your advantage
to understand the procedures early in your career.
This job may take a combination of fieldwork and
office work. If the same quality of the desired
information can be found from sources other than
actual fieldwork, do not hesitate to use them; if
necessary, use spot checks to verify certain points,
depending upon the source.
Each project requires the study of a different
set of engineering data, so it is up to the
engineering officer or the senior EAs to devise a
workable method of compilation that will suit
each particular project. It is essential that the
compiled data be complete in all respects as