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 3) 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 3), 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.
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.
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, ASCE.
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,
FL, ASCE.