ERDC/CHL CETN-IV-24
March 2000
are stored in solid-state memory. Cost, accuracy, performance, and reliability must be weighed
in selecting the optimal instrument for the location. Figure 2 shows example transect line
locations for the intensive surveys at Shinnecock Inlet. These locations for the short-term
intensive survey capture the hydraulic processes at the inlet during a tidal cycle. These data
provided the necessary information to calibrate and validate the numerical model performance at
the site.
Figure 2. Transect line locations at Shinnecock Inlet, NY
Each survey was designed to look at specific areas of interest. The 1998 survey was designed to
capture inlet processes throughout a tidal cycle, whereas the 1999 survey confirmed phenomena
predicted by a numerical model. The 1999 data were collected during an ebb cycle to observe
the movement of the ebb jet and the development of large-scale eddies.
7. Bathymetric survey. Acoustic depth sounders, such as the 200-kHz echo sounders, measure
the travel time of an acoustic pulse from a generating transducer to the waterway bottom and
back. The travel time of the reflected wave is converted into distance. The instrument must be
calibrated daily to account for electronic drift and speed of sound changes in water. Other
methods include a variety of multiple-transducer channel-sweep systems, single-transducer
multi-beam swath systems, and manual depth measurements. The most commonly used manual
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