Abstract
A series of novel image analysis techniques have been used to study surf-zone hydrodynamics taking advantage of recent advances in digital processing of images taken from video recordings of the sea surface near the coast. The use of image analysis allows the estimation of both spatial 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 different sea conditions is used to measure surface eddy diffusivities. A preliminary set of field measurements were done in the Ebro Delta where the methodology was tested. Further experiments have been performed 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 factors are wind speed and tidal and longshore currents.
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Redondo, J.M., Rodriguez, A., Bahia, E., Falques, A., Gracia, V., Sanchez-Arcilla, A. and Stive, M., Image analysis of surf zone hydrodynamics. In: Arcilla, A.S., Kraus, N.C. and Stive, M. (eds), Coastal Dynamics 94. ASCE, New York (1994) pp. 350–365.
Rodriguez, A., Sanchez-Arcilla, A., Redondo, J.M., Bahia, E. and Sierra, J.P., Pollutant dispersion in the nearshore region, modelling and measurements. Water Science and Technology 32 (1995) 169–178.
Bezerra, M.O., Castilla, R., Sanchez, M.A. and Redondo, J.M., Turbulent diffusion in enclosed beaches. In: Özhan, E. (ed.), Medcoast95, Vol. 2, Ankara (1995), pp. 1189–1198.
Bahia, E., Un estudio numerico-experimental de la dispersion de contaminantes en aguas costeras. Ph.D. Thesis, UPC, Barcelona (1997).
Diez, M., Estudio de hidrodinamica en la zona costera mediante el analisis digital de imagenes. M.S. Thesis, ETSECCPB, UPC, Barcelona (1997).
Horikawa, K., Lin, M. and Sasaki, T., Mixing of heated water dischanged in the surf zone. Proc. I.C.C.E., ASCE 15 (1978) 2563–2583.
Lippmann, T. and Holman, R., Quantification of sand bar morphology: A video technique based on wave dissipation. J. Geophys. Res. 94(C1) (1989) 995–1011.
Holman, R. and Lippmann, T., Remote sensing of nearshore bar systems — Making morphology visible. In: Coastal Sediments, ASCE, New York (1987) pp. 929–944.
Lippmann, T. and Holman, R., Phase speed and angle of breaking waves measured with video techniques. In: Coastal Sediments, ASCE, New York (1991) pp. 542–556.
Sonu, C., Tethered balloon for study of coastal dynamics. Amer. Soc. Photogram., Tech. Rep. 66 (1969) 91–103.
Medeiros C., Bezerra, M.O. and Redondo, J.M., Turbulent dispersion in confined beaches. In: Misi, A. (ed.) Proc. 39th Brazilian Geology Congress, Salvador (1996) pp. 417–422.
Thornton, E.B., Variation of longshore current across the surf zone. Proc. I.C.C.E., ASCE 12 (1970) 291–308.
Sasaki, T., Horikawa, K. and Hotta, S., Nearshore current on a gently sloping beach. Proc. I.C.C.E., ASCE 13 (1976) 626–644.
Zeidler, R.B., Coastal dispersion of pollutants. ASCE J. Waterways, Harbours and Coastal Engrg. 102 (1976) 235–254.
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Bezerra, M., Diez, M., Medeiros, C. et al. Study on the Influence of Waves on Coastal Diffusion Using Image Analysis. Flow, Turbulence and Combustion 59, 191–204 (1997). https://doi.org/10.1023/A:1001131304881
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DOI: https://doi.org/10.1023/A:1001131304881