Introduction

In the analysis of the coastal water process, numerical models are often employed to simulate flow and water quality problems. The rapid development of computing technology has furnished a large number of models to be employed in engineering or environmental problems. To date, a variety of coastal models are available, and the modelling techniques have become quite mature. The numerical technique can be based on the finite element method (Kliem et al. 2006; Jones and Davies 2007), finite difference method (Buonaiuto and Bokuniewicz 2008; Tang et al. 2009), boundary element method (Karamperidou et al. 2007; Duan et al. 2009), finite volume method (Aoki and Isobe 2007; Qi et al. 2009), or Eulerian-Lagrangian method (Cheng et al. 1984). The time-stepping algorithm can be implicit (Holly and Preissmann 1977), semi-implicit (Ataie-Ashtiani and Farhadi 2006), explicit (Ghostine et al. 2008), or characteristic-based (Ataie-Ashtiani 2007; Perera et al. 2008). The shape function can be of the first order, second order, or a higher order. The modelling can be simplified into different spatial dimensions, i.e. a one-dimensional model (Chau and Lee 1991a; Abderrezzak and Paquier 2009), two-dimensional depth-integrated model (Leendertse 1967; Tang et al. 2009), two-dimensional lateral-integrated model (Wu et al. 2004; Elfeki et al. 2007), two-dimensional layered model (Chau et al. 1996; Tucciarelli and Termini 2000), three-dimensional model (Blumberg et al. 1999; Chau and Jiang 2001, 2002; Carballo et al. 2009), and so forth. An analysis of coastal hydraulics and water quality often demands the application of heuristics and empirical experience, and is accomplished through some simplifications and modelling techniques according to the experience of specialists (Yu and Righetto 2001). However, the accuracy of the prediction is to a great extent dependent on open boundary conditions, model parameters, and the numerical scheme (Martin et al. 1999)