Modelling the run-up of significant wave groups

An approximate, but computationally exact, model is presented for evaluatin g the inundation characteristics of significant wave groups which propagate almost orthogonally to the coast on straight beaches. Run-up and depth-int egrated velocities are computed on the assumption that a group of nonbreaki ng waves of finite amplitude shoaling in shallow waters can be represented by a group of solitary-type pulses. The superposition of solitary-type puls es is studied by means of a theoretical model developed from that of Brocch ini (1998) to explicitly account for beach slope variations. Characteristic s of the groups of solitary pulses in shallow waters are defined by first g enerating a suitable number of sea states on the basis of spectral theory ( Wallops spectrum) and, subsequently. by applying the theory of 'characteris tic groups'. The model allows for direct., easy and fast computation of the flow properties of interest in terms of exact solutions. The application o f the model is illustrated by computing the run-up properties of 'typical g roups'. The role of the group characteristics and the beach slope on the ru n-up intensity is also investigated. (C) 2001 Elsevier Science Ltd. All rig hts reserved.