Deterministic Coastal Morphological and Sediment Transport Modeling: A Review and Discussion

Abstract

[1] Modern coastal ocean modeling systems are now capable of numerically simulating a variety of coastal and estuarine problems and can thus provide useful information for managing coastal zones. Here we review state-of-the-art Eulerian implementations of bottom-up sediment transport and morphological change in coastal ocean hydrodynamic models. In order to investigate the fate of suspended sediment in coastal and estuarine waters as well as the evolution of sea or river beds, sediment dynamics need to be represented at a scale relevant to the numerical discretized solution, and significant effort is devoted to parameterize sediment processes. We discuss boundary layer hydrodynamics and the computation of the bed shear stress. We also focus on approaches used to represent near-bed processes such as bed load transport and sediment erosion and deposition. Sediment diffusivities, settling velocities, and cohesive processes such as flocculation all have an impact on suspended sediment throughout the water column. We then describe the implementation of process parameterizations in coastal hydrodynamic models, explicitly reviewing five widely used systems. The approaches implemented in these coastal models may present distinct strengths and shortcomings with regard to some important issues for coastal zones, both numerical and physical. While these detailed limitations need to be considered as part of model assessment, more general issues also hinder present state-of-the-art models. In particular, sediment transport is inherently highly empirical, which is further compounded by issues arising from turbulence closure schemes. We conclude by suggesting some possible directions toward improving sediment dynamics understanding and coastal-scale predictive ability.Citation: Amoudry, L. O., and A. J. Souza (2011), Deterministic coastal morphological and sediment transport modeling: A review and discussion, Rev. Geophys., 49, RG2002,

Hydrodynamic and morphodynamic responses to surfzone seafloor perturbations

“…Numerical models have limited skill simulating field observations of surfzone sediment transport and morphological change, and the relative importance of wave-, current-, and gravity-driven suspended and bedload transport is not known for a wide range of conditions [Amoudry and Souza, 2011]. The importance of gravity-driven sediment transport in the surfzone is unknown, in part because there is a lack of field observations of the evolution of steep bathymetric features.…”

“…Most bedload formulations relate the transport to a power of the bed shear stress [Amoudry and Souza, 2011]. Thus, a bedload transport relationship modified for the presence of a sloping bed [Bagnold, 1966;Bailard, 1981;Kovacs and Parker, 1994] is given by:…”

“…Based on the ratio of the turbulent vertical velocity fluctuations to the sediment fall velocity [Gonzalez-Rodriguez and Madsen, 2011] sediment transport was dominated by bedload for the field conditions considered here. The volumetric bedload transport can be determined from an along-bed force balance on a sediment grain in the presence of waves, currents, and a sloping bed [Bagnold, 1966;Bailard, 1981;Trowbridge and Young, 1989;Fredsøe and Deigaard, 1992;Nielsen, 1992;Kovacs and Parker, 1994;Soulsby, 1997;Amoudry and Souza, 2011], and can be expressed as the sum of a component of transport in the instantaneous flow direction (owing to fluid drag on a flat bed, referred to as "flat-bed transport" ) and a component downslope (owing to the presence of a sloping bed, referred to as "downslope transport"…”

Alara, Türkiye denizel alanında sediman taşınımının modellenmesi

“…Literatürde doğal veya insan kaynaklı etkenlere bağlı olarak oluşan aşınma problemini tanımlayabilmek amacıyla sediman taşınım modelleri çalışılmakta ve uygulanmaktadır [8][9][10]. Çalışılan modeller arasında en yaygın olarak uygulanan üç boyutlu modellerden öne çıkanlar CSTM-ROMS, Delft3D, ECOMSED ve MIKE21 olarak sıralanabilir [11]. Ayrıca Chen vd.…”

Field deployment and evaluation of a prototype autonomous two dimensional acoustic backscatter instrument: The Bedform And Suspended Sediment Imager (BASSI)

“…Further, it is now widely recognised that to improve large scale sediment transport modelling, accurate parameterisations of small scale sediment processes are fundamental (Baumert et al, 2000;James, 2002;Ribberink et al, 2008;Amoudry and Souza, 2011). At present however, quantification and understanding of sediment transport processes is hampered by the difficulty in obtaining suitable measurements.…”