William A. Birkemeier, Charles E. Long and Kent K. Hathaway
Through a cooperative effort between Elizabeth City State University (ECSU) and the
Field Research Facility, a server with
additional data sets from DUCK94 will be added in the near future.
Since 1979, the Coastal and Hydraulics Laboratory (formerly the Coastal Engineering Research
Center) of the US Army Engineer Waterways Experiment Station has hosted a series of
increasingly complex, multi-investigator, multi-agency nearshore field experiments at its Field
Research Facility (FRF) located in Duck, North Carolina, USA. Three experiments, DELILAH
and DUCK94, and SandyDuck, all evolved from scientific and pragmatic successes of prior work
at this site, and have the basic objectives of improving fundamental understanding and modeling
of surf zone physics. The emphasis in DELILAH was surf zone hydrodynamics in the presence
of a changing barred bathymetry. DUCK94 and SandyDuck have added components to resolve
sediment transport and morphologic evolution at bedform scales from ripples to nearshore bars.
DUCK94 was designed as a pilot effort to test instruments and procedures required for the more
comprehensive SandyDuck experiment. This document summarizes DUCK94 including
participants, environmental conditions, data collected, and data availability.
Success of DELILAH, and the evident need for more detailed information about sediment
transport and morphologic evolution that results from hydrodynamic forcing, initiated interest in
further field work to be supported by the US Army Corps of Engineers, Office of Naval
Research, the Naval Research Laboratory and the US Geological Survey. A plan for two
additional field experiments developed. The first, DUCK94, was intended as a test run for new
instrumentation, a more formal experiment organization, and more complicated logistics in
preparation for SandyDuck, the second experiment. DUCK94 was scheduled for August and
October 1994 to take advantage of the synergy offered by the National Science Foundation's
Coastal Ocean Processes (CoOP) experiment (Butman, 1994), being conducted at the FRF during
that time. The following focus topics were established as fundamental to improved
understanding of surf zone sediment transport:
a. small and medium scale sediment transport and morphology;
b. wave shoaling, wave breaking, and nearshore circulation;
c. swash processes including sediment motion.
Considerable interest was expressed for DUCK94. Table 1 lists the 19 organizations that
participated, involving more than 100 scientists, students, and technicians. Instrument
measurements were complemented by observations from ground- and aircraft-based radar and
video systems. Table 2 lists the 31 basic studies, along with the principal investigators, their
primary focus areas, and experiment durations. The extensive instrumentation resulted from
consideration of relevant measurement scales required to address SandyDuck science objectives.
Guidance was provided by using measured velocity data from DELILAH and sediment transport
modeling. Based on this analysis, a general nearshore instrumentation array was designed
(Birkemeier & Thornton, 1994). The full array, shown in Figure 1, was used during the October
phase of DUCK94. An abbreviated form of this array was used in the August segment of the
experiment. Formal dates for DUCK94 were 8-24 August and 1-24 October, though some
investigations (Table 2) of various durations were underway between June and November.
A wide variety of instrumentation was used in DUCK94. Conventional total-station surveying
techniques were used in subaerial morphology studies (29, referring to investigations by
experiment number in Table 2), minigrid surveys (15), and positioning of all stationary
instruments. Central to the main layout were cross-shore arrays of instrument clusters (11), each
containing an electromagnetic current meter, a pressure gauge, an acoustic altimeter, and a
thermometer (Fedderson, et al.,1997). The altimeters permitted the first comprehensive real-time
measurements of bottom changes (8) (Gallagher, Elgar & Guza, 1997). A large number of
suspended sediment concentration gauges were deployed, including optical backscattering
sensors (16, 22, 26, 30), and less intrusive fiber- optic backscattering sensors (1). The Coherent
Acoustic Sediment Probe (Stanton & Thornton, 1997) was mounted on a mobile sled along with
current meters, pressure gauges, scanning sonars, and void fraction sensors (20, 25, 26). The
Sensor Insertion System,
located on the FRF pier, provided a stable, mobile platform for sediment transport measurements
during high-energy conditions (1, 22). In situ (16) and CRAB-mounted (25) side-scan sonars
provided observations of bottom bedforms, including megaripples. Most array positions
included one or more current meters (1, 3, 11, 12, 13, 15, 16, 18, 22, 26, 30). Incident wave
conditions were monitored with directional wave buoys (6, 19), and a direction-sensing array of
pressure gauges (21).
Dynamics measurements were complemented by a series of geologic studies that included
surface sediment samples (24) (Stauble & Cialone, 1997), short cores, box cores, and vibracores
(4). Several remote sensing systems were used. Surf zone and swash processes were observed
with tower-mounted video systems (14, 17, 20). Observations were also made with land-based
marine radar systems (27), coherent radar systems (10), airborne synthetic aperture radar,
topographic lidar, visible and hyperspectral light imaging, and scanning radar altimetry (5, 7, 28).
Three studies examined fundamental nearshore acoustic behavior (16, 23, 31).
Environmental conditions during the October phase of DUCK94 are illustrated in Figure 2. Two
high-wave events occurred. The first was on 2-4 October, wherein wave heights exceeded 2.5 m.
Wave heights reached 4.5 m during the second storm, an eight-day event beginning on 10
October. During the larger storm, large bottom changes were accompanied by a complex
nearshore circulation pattern wherein wave-driven currents in the surf zone were opposed by
strong wind-driven longshore flows offshore. As shown in Figure 2, currents in the nearshore
trough changed from about 1 m/s to the south at the beginning of the storm on 10 October to
about 1 m/s to the north just prior to the peak of the storm on 15 October.
Figure 3 illustrates four of the 12 minigrid surveys collected during October. Following a pattern
similar to that observed in DELILAH, the bar moved offshore and became more linear in the
initial part of the 10 October storm. High waves prevented daily surveys until 21 October, when
the survey revealed that a very large rip channel had developed. Evolution of this channel is
evident in video time exposure images depicted in Figure 4. Sequences of profile data through
the region of the rip are shown in Figure 5, where it is seen that the bar crest moved 100 m
seaward, causing 1.2 m of deposition at its most seaward observed location on 18 October. By
21 October, the bar crest had begun migrating landward.
DUCK94 data are being analyzed, and research results are beginning to appear in the literature.
Preliminary findings were discussed at a post-experiment meeting (summarized by Long &
Sallenger, 1995), where adequacy of the DUCK94 experiment plan was also evaluated in
preparation for SandyDuck.
The investigators have agreed on a data sharing policy that offers protection of data by collecting
investigators, encourages collaboration, and provides for eventual public release. This policy is:
a. global release of all data three years after the experiment;
b. responsible investigators will be identified when data sets are used by others;
c. prior to three-years, data shared by agreement between individual investigators;
d. any manuscript based on shared data must be approved by all responsible investigators
prior to submission;
e. no third-party data dissemination;
f. principal investigators control use of their data.
Data from DUCK94 are not yet generally available. An extensive discussion of the DUCK94
experiments, including tables listing sensors, data sets, and a summary of results, findings and
publications, is available through the above web site. It is anticipated that DUCK94 data will
become generally available late in 1998.
Birkemeier, W. A. and Thornton, E. B., 1994, "The DUCK94 Nearshore Field Experiment,"
Proceedings of the Conference on Coastal Dynamics '94, 815-821.
Butman, C. A., 1994, "CoOP: Coastal Ocean Processes Study," Sea Technology, 35:1, 44-49.
Fedderson, F., Guza, R. T., Elgar, S., and Herbers, T. H. C., 1997, " Cross-shore Structure of
Longshore Currents during DUCK94", Proceedings of the 25th International Conference on
Coastal Engineering, Orlando, FL, ASCE.
Gallagher, E. L., Elgar, S., and Guza, R. T., 1997, "Observations and Predictions of Sand Bar
Motion," Proceedings of the 25th International Conference on Coastal Engineering, Orlando, FL,
Long, C. E. and Sallenger, A., 1995, "Experiment at Duck, N.C. Explores Nearshore Processes,"
EOS Transactions of the American Geophysical Union, 76:49.
Stanton, T. P. and Thornton, E. B., 1997, "Reynolds Stress and Small-Scale Morphology
Measurements during DUCK94," Proceedings of the 25th International Conference on Coastal
Engineering, Orlando, FL, ASCE.
Stauble, D. K., and Cialone, M. A., 1997, "Sediment Dynamics and Profile Interactions:
DUCK94," Proceedings of the 25th International Conference on Coastal Engineering, Orlando,
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