Wave Reflection on a Two-Slope Steep Beach
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Authors
Watson, David H.
Subjects
Wave Reflection
Advisors
MacMahan, Jamie
Date of Issue
2012-03
Date
Mar-12
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
Wave reflection of sea-swell (0.050.20 Hz) energy on a two-slope (1/7.6 nearshore and 1/19 offshore) steep beach with no subaqueous sandbar is studied. The dataset were collected using a cross-shore array of 4 Acoustic Doppler Current Profilers measuring velocity and pressure at 1 Hz continuously for 40 days. Measurement of pressure and velocity at the same location allows data to be decomposed into onshore and offshore components to determine reflection. The long data set captured a wide range of wave conditions at various tidal stages. Observations show low amplitude long period waves produced energy reflection coefficients up to 80%, with most in the 3050% range. There was a measured increase in the number of nodes and anti-nodes at higher frequencies and observations farther offshore consistent with theory. Field data were compared to an analytical two-slope model that predicts the cross-shore nodal structure of standing waves. The predicted locations of nodes and anti-nodes are in good agreement with observations.
Type
Thesis
Description
Series/Report No
Department
Meteorology
Physical Oceanography