Study on the Influence of Waves on Coastal Diffusion Using Image Analysis

BEZERRA O; DIEZ M; MEDEIROS C; A RODRIGUEZ; E BAHIA; SANCHEZ ARCILLA A; REDONDO JM

Applied Scientific Research

Kluwer Academic Publishers.

Año: 1998 vol. 59 p. 191 - 204

0003-6994

A series of novel image analysis techniques have been used to study surf-zone hydrodynamicstaking advantage of recent advances in digital processing of images taken from videorecordings of the sea surface near the coast. The use of image analysis allows the estimation of bothspatial and temporal characteristics of wave fields, surface circulation and mixing in the surf zone.The dispersion of blobs of dye released at different distances from the coastline under very differentsea conditions is used to measure surface eddy diffusivities. A preliminary set of field measurementswere done in the Ebro Delta where the methodology was tested. Further experiments have beenperformed at Vilanova, Spain and Recife, Brazil.There is an increase of diffusivity with wave height but only if the wave Reynolds number, Rw,is greater than 103. No such trend is observed for Rw greater than 106. The other important factorsare wind speed and tidal and longshore currents.