In this paper we consider the methods of constructing difference schemes of the same type for three nonlinear dispersive models of wave hydrodynamics. These models differ in that they take into account nonlinearity to a variable degree and in the method of introducing the integrated velocity. The aim of this paper is to estimate both the properties of difference schemes proposed, which have first been studied in a linear approximation, and those of the models approximated by them. They are studied in the problem on interaction of a long wave with a shelf at the bottom when the effect of nonlinearity and dispersion on the behaviour of the wave becomes substantial. We compare the numerical calculations with the experimental data. This allows us to preestimate the simplifications used when deriving the models and make some progress in the applicability of nonlinear dispersive equations to the solution of the problems on the transformation of long waves in shoal water.In this paper we consider the methods of constructing difference schemes of the same type for three nonlinear dispersive models of wave hydrodynamics, which are used to describe moderately long waves in various practical situations. These models are the systems of nonlinear equations with dispersion with respect to the elevation of the free surface and the integrated velocity. The integrated velocity is understood to be a function independent of a vertical coordinate and somehow related to the flow velocity.Although such models are extensively used in numerical modelling, there are not many works on the investigation of numerical algorithms used. A brief survey of some works is given in [7]. We can also mention the works [1,3,4,6,8].The aim of this paper is to estimate both the properties of difference schemes proposed and those of the models approximated by them. They are studied in the problem on interaction of a long wave with a shelf at the bottom when the effect of nonlinearity and dispersion on the behaviour of the wave becomes substantial.We take three familiar models that describe the nonlinear processes of the propagation of water waves, taking into account dispersion. These are a complete nonlinear dispersive model that is derived without restrictions to nonlinearity and two weakly nonlinear models of the Boussinesq type. The derivation of the first model is described in detail in [13,15]. If we drop the nonlinear dispersive terms in this model, we obtain a model of the Boussinesq type, which is proposed in [10]. At present it is one of the well-known hydrodynamic models extensively used in calculations. The latter of the above models essentially differs from the first two models by the method of introducing the integrated velocity. In the first two models we consider as the * The work was supported by the Russian Foundation for the Basic Research (94-05-16281). 'Institute of Computational Technologies, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia Brought to you by | University of Queensland -UQ Library Authen...