Numerical modelling of long waves amplification at Marina di Carrara Harbour

Abstract

In this paper we test two different numerical models for the assessment of the long waves climate inside a harbour, induced by nonlinear interaction of short waves. One model is based on the nonlinear Boussinesq Type Equations; given the properties of the incoming short waves it is able to model the growth of the long waves, and their propagation and amplification inside the harbour basin. The other model uses a simplified formula for the calculation of the incoming long waves, and solves the linearized Mild Slope Equation to reproduce the long waves penetration into the harbour. The models are applied to the harbour of Marina di Carrara (Italy), where a field measurement network of both short and long waves is operational since 2005. Short waves records are obtained by a directional buoy deployed at about 1km offshore the harbour entrance, whereas the long waves measurements inside the basin are obtained from 8 pressure transducers installed along the harbour inner perimeter. About 3 years of measurements (December 2005 to October 2008) are considered in this paper. Both the models are shown to provide reasonable estimates of the long waves climate inside the harbour. Advantages and disadvantages of each are discussed.