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Unformatted text preview: Journal of Coastal Research 26 1 184-198 West Palm Beach, Florida January 2010 Limits of Wave Runup and Corresponding Beach-Profile Change from Large-Scale Laboratory Data Tiffany M . Roberts', Ping Wang, and Nicholas C. Kraus* †Department of Geology University of S o u th Florida 4202 E a s t Fowler A v e n u e Tampa, F L 33620, U.SA. E-mail: tmrobert@ cas.usf.edu ‡U.S. Army E n g in e e r R esearch an d Development C enter Coastal an d Hydraulics L aboratory 3909 Halls F e rry Road Vicksburg, M S 39180-6199, U.S.A. ABSTRACT ROBERTS, T.M.; WANG, P., and KRAUS, N.C., 2010. Limits of wave runup and corresponding beach-profile change from large-scale laboratory data. Journal of Coastal Research, 26( 1), 184-198. W est Palm Beach (Florida), ISSN 0749- 0208. The dataset from the SUPERTANK laboratory experiment was analyzed to examine wave runup and the correspond¬ ing upper limit of beach-profile change. Thirty SUPERTANK runs were investigated that included both erosional and accretionary wave conditions with random and monochromatic waves. The upper limit of beach change U L was found to approximately equal the vertical excursion of total wave runup, R t w . A n exception was runs where beach or dune scarps were produced, which substantially limit the uprush of swash motion to produce a much reduced total runup. Based on the SUPERTANK dataset, the vertical extent of wave runup above mean water level on a beach without scarp formation was found to approximately equal the significant breaking wave height, H b s . Therefore, a new and simple relation R tw = H b s is proposed. The linear relationship between total runup and breaking wave height is supported by a conceptual derivation. In addition, the relation is extended to U L = R tw = H b s to approximate the upper limit of beach change. This formula accurately reproduced the measured upper limit of beach change from the three-dimensional experiments in the Corps' large-scale sediment transport facility. For the studied laboratory cases, predictions of wave runup were not improved by including a slope-dependent surf-similarity parameter. The limit of wave runup was substantially less for monochromatic waves than for random waves, attributed to absence of low- frequency motion. A D D I T I O N A L I N D E X W O R D S : Beach erosion, nearshore sedim en t transport, w a ve breaking, cross-shore sedim en t transport, physical m odeling, surf zon e processes. INTRODUCTION Accurate prediction of the upper limit of beach change is necessary for assessing large morphologic changes induced by extreme storms. The upper limit of beach change is controlled by wave breaking and the subsequent wave runup. During storms, wave runup is superimposed on the elevated water level due to storm surge. Wang et al. (2006) found the highest elevation of beach erosion induced by Hurricane Ivan in 2004 to be considerably greater than the measured storm-surge level, indicating that wave runup played a significant role in...
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This note was uploaded on 02/19/2010 for the course GEOL 500 taught by Professor Niemitz during the Spring '10 term at Dickinson.
- Spring '10