Nearshore Hydrodynamics and Sediment Transport


The nearshore zone extends from the landward limit of the swash to the seaward point at which in­cident waves commence breaking. This zone encompasses a large range of scales and types of fluid motion, including short and long waves, currents, turbulence and vortices. Sediment transport in the surf and swash zones control the nearshore and beach morphology. Numerical models of processes in these zones include many simplifications. The main objective of this project is to de­velop further understanding of the sediment transport in the nearshore zone.

The major areas to be investigated are:

  • Numerical simulation of surf-swash zone hydrodynamics including turbulent flow and sediment transport;
  • Numerical modeling of wave-beach groundwater interaction and its effects on nearshore sedi­ment transport and beach profile changes;
  • Temporal and spatial profiles of sediment concentration and velocity for various grain sizes and wave conditions;
  • Time-varying and time-averaged sediment flux distributions for different beach and flow condi­tions;
  • Net on/off-shore sand transport rates varying with flow conditions;
  • Influence of wave conditions on groundwater dynamics and salinity beneath granular beaches; and
  • Extent of mixing between fresh groundwater and seawater in the nearshore region.

The project includes model formulation and development, and model validation. A com­prehensive two-phase, onshore/offshore flow model will be developed. The model, built on an exist­ing research codes, will be based on the Euler-Euler coupling of the governing equations for the se­diment and fluid phases. Each phase is modeled using the Navier-Stokes equations, with the coupl­ing between the phases accounting for interphase mass and momentum conservation. Other model elements to be included are: (i) k-ε closure model for turbulence generation and translation processes; (ii) free-surface motion modeled using the Volume-of-Fluid technique; and (iii) saturated-unsaturated den­sity-dependent groundwater flow in an unconfined aquifer.


Fig. 1: Schematic illustration of the nearshore (Elfrink and Baldock, 2002).


Fig. 2: Tide-induced (a) salt distribution, (b) oxygen distribu­tion with no natural oxygen-consuming processes and (c) oxygen distribution with natural oxy­gen consumption in a tidally-influenced near-shore aqui­fer. The upper saline plume (USP), saltwater wedge and freshwater discharge zone (FDZ) are denoted in (a). The arrows represent the groundwater flows averaged over a tidal cycle. After Robertson et al. (2008).


Robinson, C.E., Li, L., Barry, D.A. 2007. Adv Water Resour 30, 851-65.

Elfrink, B., Baldock, T.E. 2002. Coast Eng 45, 149-67.