SUPERTANK Swash 

 Measurements 1 



Introduction 



Background 



Ten capacitance-based wave gauges were placed at 2- to 6-ft (0.61- to 

 1.83-m) intervals in the vicinity of the shoreline and on the beach face to 

 measure water surface and sand bed elevations in the swash zone. These 

 gauges complement the 16 resistance wave gauges that were positioned at 

 12-ft (3.66-m) intervals from the wavemaker to the mid surf zone (Chapter 3). 

 As a result, mean and time-varying water surface elevations were measured at 

 26 locations along the full length of the wave channel. In the swash zone, the 

 capacitance-based wave gauges measured wave propagation (uprush and down- 

 rush) on the beach face. In addition, these gauges were partially buried in the 

 sand beach and recorded the elevation of the saturated sand surface during 

 those times when the sand was exposed between successive wave events. 



Objectives of the swash measurements 



The major objective of the swash measurements at the SUPERTANK 

 Laboratory Data Collection Project was to provide data on both mean water 

 level and wave transmission in the nearshore and swash regions. This infor- 

 mation includes both spectral and statistical, or time-series, wave parameters 

 at each gauge location. Data were analyzed in three ways: (a) the total water 

 level as originally measured, (b) the low-frequency water level based on low- 

 pass filtering of the total record, and (c) the high-frequency water level based 

 on high-pass filtering of the total record. This data set supplements that ob- 

 tained from the resistance wave gauges installed offshore and provides wave 

 transformation information to near the runup limit. 



74 



'Written by David L. Kriebel, U.S. Naval Academy. 



Chapter 4 SUPERTANK Swash Measurements 



