INSHORE-NEARSHORE MORPHODYNAMICS - A PREDICTIVE MODEL

The two-dimensional topography, developed on a sandy sea bed between surf base and the breaker zone, is computed using (i) sediment gain or loss per unit bed area = zero, (ii) simple models of sediment drift in terms of, firstly, simplified saltation under Stokesian waves, and secondly, frictional wave work on the sea bed, (iii) the drift tendency in direction of wave propogation being offset of the local sea bed gradient. An input contour line at surf base is assumed, across which the input wave train is propogated. Using standard wave refraction combined with (i) to (iii), above, an equilibrium topography is generated by iteration. Inshore of the breaker line, longshore currents generated by radiation stress are combined with the gradient effect to balance sediment drift, producing bar - trough topography.