Turbulent diffusion in enclosed beaches  <B>Turbulent diffusion in enclosed beaches</B><P>M.O. Bezerra1, R. Castilla2, M.A. Sanchez2 and J.M. Redondo2</B><I><P> 1 Dept.Fisica Aplicada, U.P.C. Campus Nord, Barcelona, Spain <BR> 2 Univ.Pernambuco, Recife, Brasil</I><P> Abstract<P> Field measurements at an enclosed mediterranean beach have been made using a variety of techniques in order to obtain a comprehensive description of the flow and boundary conditions. San Gervasi beach in Vilanova i la Geltru, an enclosed beach, provides a good test case for the study of wave generated turbulence without the superposition of a large scale longshore current. Measurements performed during 1995 under a variety of atmospheric and oceanic conditions include: Salinity and Temperature profiles at selected sites as well as wind measurements and bottom sediment collection with a small vessel. Bathimetric measurements of the area and video recordings of the incident and breaking wave field as well as detailed measurements on the dispersion of blobs of dye and of floats. The spectra obtained from video measurements agree with those obtained from velocity recordings as shown by Redondo et.al.(1994). Other visualization techniques which allow the estimation of integral time and length scales are presented, Redondo et.al.(1994b). Eddy diffusivity measurements are lower than those often quoted in the literature, showing a marked anisotropy.<P>