Comparative Study of Spectra Transformation of the Wave Field in the Near-shore Zone, Surf Zone and Swash Zone in the Ebro Delta

MOSSO C; JP SIERRA; DIEZ M; SANCHEZ ARCILLA A; A RODRIGUEZ; SANTAS JC; VICTOR RUIZ

Bangor

Workshop; FANS Bangor Workshop; 1998

FANS

Experimentalresults of wave energy transformation by means of Spectral Analyses in theNearshore (NS), Surf (SZ) and Swash (SwZ) Zone of the Trabucador?s Bar in theEbro Delta are here presented. During the shoaling-breaking processes, the waveenergy is transformed to different physical phenomena in the Nearshore Zone,where the waves experiment the sharper transformations, increasing the waveheights (so the steepness), that ultimately lead to breaking, which is the mainlongshore currents, dispersion and sediment suspension driving mechanism. Theamount of energy that is transformed, i.e. wave energy transferred to highfrequency (for example, turbulence and energy dissipation due to breaking) orto low frequency (infragravity waves or Nearshore currents) oscillations is notwell understood nor described in the state of the art. The spectral analysis ofthe wave field time series allows to transform the surface elevations in thetime domain to energy in the frequency domain. Due to that, the aim of thiswork is to experimentally study these transformations and to analyse the wavespectrum evolution when a wave train propagates to the coast. In order to studythe swash zone, with aid of the digital analyses of video images, theoscillations in the beach face will be taken to heights by superimposing itwith the topography, allowing the same units of power as the wave spectra. Thiswork is a first attempt to quantitative study the transformations of the waveenergy in the Nearshore.