Theoretical analysis of wave-induced gravel movements

Abstract

One of the primary objectives of coastal research is the erection and testing of mechanically sound, predictive models for the two- and three-dimensional form of beach and nearshore bathymetries in order to account for and to predict coastal response to changing wave, tidal and sea-level conditions. The relationship between flow parameters and the mass transport of non-cohesive sedimentary particles has long been of importance in fluvial, aeolian and marine environments, but despite the existence of many numerical beach models, any of which might be developed to account for longer-term evolution, it is apparent that fundamental problems remain, not only in the representation of hydrodynamic and sediment dynamic processes but also in the choice of appropriate forcing functions for long-term simulations in real-time or quasi-real-time. An alternative is developed here in which frequency domain representations of a simplified set of process and response algorithms are presented, so that hydrodynamic, sediment dynamic and geomorphological parameters are related by a simple series of spectral gain functions. In particular, we concentrate on the relationship between the nearbed orthogonal flow spectrum and the resulting sediment mass transport rate. Numerical solutions, using both non-linear and linearized forms of the momentum equation, are presented.