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Sediment transport in the coastal zone

Sawczyński S., Kaczmarek L. M.

Technical Sciences / University of Warmia and Mazury in Olsztyn

2014

nr 17(2)

165--180

The paper provides basic information on the description of sediment transport in the coastal zone of the sea. It explains the mechanisms of sediment movement under the influence of the waves and currents interactions, characteristic for the coastal zone. It presents models describing the movement of sediment in the regime of flat bottom, making their divided in accordance with the method of description of vertical structure of sediments transport. Particular emphasis is placed on modeling of graded sediment transport. It presents basis for the three-layer model of graded sediment transport. This allows, among others, the analysis of the variability of particle size distribution in the whole area of sediment movement. The model assumes that the movement of sediment is divided into three layers: bedload layer, contact load layer and outer flow region, as a result of the shear stress influence on the bottom.

Modeling bathymetry changes in the coastal zone - state of knowledge analysis

Sawczyński S., Kaczmarek L. M.

Technical Sciences / University of Warmia and Mazury in Olsztyn

2014

nr 17(3)

219--233

In this paper we briefly review the mathematical models used to describe the bathymetry changes in time and space. Overview of the models was carried out with particular emphasis on the problems encountered during the nonlinear equation solution, commonly used to describe the morphology of the bottom in the coastal zone of the sea. In contrast to the commonly used approach, it is proposed a linear relationship between volumetric flow of sediments transport rate and thickness of the layer of sediment grains, closely adjacent to each other and staying in motion. This linear relationship allows to precisely define the initial - boundary conditions and to apply the numerical scheme of finite difference method of „upwind” at the accuracy of the first order, not distorted by numerical errors. The author’s method also allows to implement changes to the description of the bathymetry of simultaneous changes in the distributions of the sediment grain size.

Modelling bathymetry changes within a waterway versus a laboratory experiment

Sawczyński S., Kaczmarek L. M., Biegowski J.

Technical Sciences / University of Warmia and Mazury in Olsztyn

2013

nr 16(1)

41--62

A three-layer theoretical model for transport of graded sediments was used in our analysis of the silting-up of waterways tested under laboratory conditions. The experiment was conducted in a laboratory basin, in which waves and a current were generated. The current interacted with the waves propagating perpendicularly to the direction in which it was flowing. It was assumed in the calculations that the sediment was entrained from the bed and suspended due to the impact of waves on the bed, after which it was transported by the current along the cross-shore profile of the navigation channel. Thus, it was assumed that the bathymetry changes occur only as a result of changes in the suspended load transport rate. The bed topographic modifications modelling results are in good agreement to the laboratory experimental results, including the rate of silting up the waterway and the bed reconfiguration. The key factor in the calculations concerning the waterway bed reconfiguration proved to be the inclusion of the effect of sediment size sorting on predicting the rate and character of bathymetry changes.