ERDC/CHL CETN-IV-24
March 2000
Some of the data parameters that may be considered include tide, salinity, suspended sediment,
bed material, waves, meteorological factors, tidal current, and bathymetry. Not all of these
parameters need to be monitored in every study. The specific site problem will dictate the
method of investigation and data needs in support of that method. A well documented
reconnaissance trip will help this step. A site visit increases a basic understanding of the
problems and points the engineer/scientist in the proper direction in developing further plans.
4. Select equipment to match the parameters to be measured. The parameters that are driving
the conditions at the inlet and the equipment available to measure these parameters must be
matched to provide a successful execution of the field investigation.
a. What period of record is necessary to capture normal conditions at the site?
b. Is it necessary to capture a storm event as a representative data set?
c. Are emergency retrieval plans for equipment necessary at the site?
d. Is there a significant seasonal variability?
e. How will aquatic fouling affect the data types necessary for this project?
f. What is the servicing period required to eliminate the effects of aquatic fouling?
g. What are the limiting battery requirements for the instruments?
h. What sample rates are needed for each parameter to support the analysis method?
i. What internal memory size is needed to accommodate the sample rate and duration
period between service intervals.
j. How will the instruments be mounted?
k. Can the instruments be serviced from land?
l. Will divers be necessary to deploy, service, or retrieve the instruments?
m. Is external power available at each site?
Then equipment is matched to the period of collection and the needed servicing intervals to
ensure collection of accurate and reliable data.
DATA COLLECTION EQUIPMENT: These parameters include, but are not exclusive to, tide,
salinity, suspended sediment, waves, meteorological factors, tidal current, bathymetry, and bed
material. Various types of data collection equipment are available to aid in collecting the
necessary data.
1. Water level. Water level elevation can be recorded using solid-state electronic instruments.
These instruments typically contain a strain gauge or quartz-type pressure transducer that records
the absolute pressure of the water column above the instrument. The accuracy and resolution of
these transducers are expressed as a percentage or fraction of the total range. Some instruments
are vented to the atmosphere to compensate for atmospheric pressure. However, most
instruments are not vented and, after the instrument is initially calibrated, changes in barometric
pressure will appear as changes in depth. If a model that is not vented is used, an additional unit
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