Geometry, migration and evolution of small-scale bedforms generated by regular and irregular waves

Ripples generated by both regular and irregular waves have been experimentally investigated. In particular, their geometry at the equilibrium (i.e. height, length and steepness) has been analyzed and compared with semi-empirical predictive models. It has been observed that in the investigated range no distinction between ripples generated by regular or irregular waves is detectable, even though the equilibrium configuration is reached through different mechanisms. Moreover, it has been found that ripples migrate as soon as they appear and their velocity of migration qualitatively agrees with theories based on stability analyses recently proposed. Starting from results in literature, new semi-empirical formulae are provided for calculation of equilibrium characteristics of ripples. (C) 2002 Elsevier Science B.V All rights reserved.