Long shore currents and flow resistance in the surf zone

Experimental and numerical results of long shore currents measured during DELTA'93 field experiments are presented. Velocities were measured in the Ebro River delta, with six electromagnetic current meters distributed from 0. 1 m above the bottom up to the water surface. The results are compared to numerical models based on Fredsoe, J. (1984) and Sanchez Arcilla, A. et al. (1992) works, and present new aspects respect to what has been generally accepted for the surf zone. The vertical distribution of long shore currents is opposite to the assumed quasi-uniform vertical profiles, thus ratifying the logarithmic profiles hypothesis. The maximum of the horizontal profile was located near the trough of the barred crosshore profile and varies according to the wave forms. Also, experimental values of friction coefficients and roughness heights have been obtained and compared to state-of-the-art formulations.