ERDC/CHL CHETN-II-46
March 2002
Experiences from shoreline change modeling studies, and results from reanalysis of data used to
derive the CERC formula by several researchers, suggest that the formula (using a Kl value of
0.39) may overpredict the LST rate when considering the entire wave climate for a particular
site. Miller (1998, 1999) found the CERC formula predicted LST rates during storms reasonably
well. The field measurements during storms cited by Miller do not capture swash transport. If
swash transport was as significant during the storm events that were studied, as is suggested by
the laboratory measurements, the CERC formula may in fact underpredict LST rates during high-
energy conditions. Evidence from field and laboratory experiments suggests that the CERC
formula overestimates LST for lower wave conditions. Evidence suggests that the Kamphuis-91
formula is a better estimator of LST for lower wave conditions, but it may produce an
underestimate.
Based on presently available information from a number of sources, the following guidance is
offered. When attempting to develop long-term LST estimates for a site using a long-term
record of measured or hindcast wave information, coastal engineering practitioners should
consider using the Kamphuis-91 formula to develop a lower-bound estimate and the CERC
formula to derive an upper bound estimate. A Kl value of approximately 0.2 might provide more
realistic estimates for expected LST rates using the CERC formula, rather than a value of 0.39.
However, a more appropriate Kl value can be estimated from a shoreline change model
calibration/validation exercise and/or scaling of calculated LST rates to match those derived
from knowledge of the local sediment budget. For specific events, at present, it seems most
appropriate to use the CERC formula for storm events and the Kamphuis91 formula for low-
energy events (less than 1 m in height). Additional field and laboratory data and research, are
needed to develop more accurate and robust predictors for both the magnitude of LST and its
cross-shore distribution pattern, which properly account for factors such as breaking wave type
and grain size.
ADDITIONAL INFORMATION: Questions about this CHETN can be addressed to
Mr. Bruce A. Ebersole (601-634-3209, e-mail: ) The contri-
.
butions of William Halford, David Daily, and Tim Nisley, who provided technical support to this
study, are gratefully acknowledged. This technical note should be cited as follows:
Wang, P., Ebersole, B. A., and Smith, E. R. (2002). "Longshore sand transport
initial results from lage-scale sediment transport facility," ERDC/CHL CHETN-
II-46, U.S. Army Engineer Research and Development Center, Vicksburg, MS.
REFERENCES
Bodge, K. R. (1986). "Short-term impoundment of longshore sediment transport," Ph.D. diss., University of
Florida, 345 p.
Bodge, K. R., and Dean, R. G. (1987a). "Short-term impoundment of longshore transport," Proceedings of Coastal
Sediments '87, ASCE, New York, 468-483.
. (1987b). "Short-term impoundment of longshore sediment transport," Miscellaneous Paper CERC-87-7,
U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.
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