ESTIMATING WAVE HEIGHTS FROM PRESSURE MEASURED IN SAND-BED

Comparison of predicted with observed attenuation of pressure fluctuat ions shows that wave heights can be estimated with observations from a pressure sensor that is buried a known depth in fine sand. The attenu ation of pressure fluctuations within the sand bed under unbroken shoa ling waves, bores in the surf zone, and swash near the shoreline was m easured with vertical stacks of buried pressure sensors. The attenuati on increased with increasing frequency and depth below the bed surface , consistent with previous observations under nonbreaking waves in dee per water and with model predictions based on pore-elastic theory, in the limit of an infinitely deep soil skeleton that is much more compre ssible than the pore fluid, the predicted pressure fluctuations decrea se exponentially with increasing burial depth, and the attenuation is independent of the sediment properties. For the fine-grained sand beds considered here, this exponential limit accurately predicts the obser ved attenuation.