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1

Modified logarithmic distribution of wind-driven flow velocity in remote foreshore of the non-tidal sea

Ostrowski Rafał, Stella-Bogusz Magdalena

Oceanologia

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2023

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Vol. 65 (4)

556--563

EN

The paper presents the results of the novel modelling of the wind-driven current in the southern Baltic Sea. The steady current is accompanied by wave-induced orbital velocities. The bed boundary layer related to wave-induced oscillatory flow gives rise to the appearance of additional shear stresses affecting the wind-driven current. This impact included in the wind-driven current model yields a modified logarithmic velocity distribution. Theoretical velocity profiles are compared with the field data. The measurement database includes wind, wave and current parameters. The velocities and directions of the wind were collected from the anemometer installed at the Coastal Research Station (CRS) in Lubiatowo. Wave-current parameters at a depth of about 17 m were obtained from a location of approx. 1.5 Nm from the shoreline in the vicinity of CRS Lubiatowo. The study site hydrodynamics is typical of the south Baltic coast. The analysis shows good agreement between the measured flow velocities and the theoretical vertical distributions in the form of the modified logarithmic profile.

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Coastal hydrodynamics beyond the surf zone of the south Baltic Sea

Ostrowski R., Stella M., Szmytkiewicz P., Kapiński J., Marcinkowski T.

Oceanologia

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2018

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No. 60 (3)

264--276

EN

The paper presents experimental and theoretical investigations of hydrodynamic processes in a coastal region located close to the seaward boundary of the surf zone. The analysis is based on field data collected near Lubiatowo (Poland) by measuring equipment operated simultaneously by the Institute of Hydro-Engineering of the Polish Academy of Sciences (IBW PAN) and the Maritime Institute in Gdańsk (IMG). The data consist of wind velocity and direction measured at the IBW PAN Coastal Research Station (CRS) in Lubiatowo, deep-water wave buoy records, current profiles and sea bottom sediment parameters. Mean flow velocities measured in the entire water column have almost the same direction as wind. Nearbed flow velocities induced by waves and currents, as well as bed shear stresses, are modelled theoretically to determine sediment motion regimes in the area. It appears that the nonlinear wave-current interaction generates bed shear stresses greater than those that would result from the superposition of the impacts of waves and currents separately. The paper discusses the possibility of occasional intensive sediment transport and the occurrence of distinct seabed changes at greater coastal water depths adjacent to the surf zone. It was found that this can happen under the joint influence of waves and wind-driven currents.

3

On Uncertainties in Determination of Sediment Transport Rates in Coastal Regions

Ostrowski R.

Archives of Hydro-Engineering and Environmental Mechanics

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2016

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Vol. 63, nr 4

265--280

EN

The paper deals with research uncertainties, difficulties, inaccuracies and unreliabilities related to the modelling of physical phenomena involving coastal lithodynamics. The considerations are focused on processes of wave transformation, wave-driven currents and sediment transport itself. It is shown that possible inaccuracies at individual stages of the modelling of coastal hydrodynamics can lead to serious uncertainties with respect to the ultimate modelling output, namely bed shear stresses and sediment transport rates. These inaccuracies result mostly from arbitrarily assumed parameters and constants. Other modelling biases discussed in the paper comprise simplifications and approximations with respect to sediment resources and size-graded properties, randomness of hydrodynamic impacts, bottom roughness and land-borne factors involved in coastal lithodynamics.

4

Influence of Nearshore Mining Pits on Hydro- and Lithodynamics of a Dissipative Coastal Zone: Case Study of the Hel Peninsula (Poland)

Ostrowski R., Skaja M.

Archives of Hydro-Engineering and Environmental Mechanics

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2016

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Vol. 63, nr 4

237--252

EN

The paper deals with a sandy shore located on the open sea side of the Hel Peninsula in Poland (the south Baltic Sea coast). The study site displays a cross-shore profile that intensively dissipates wave energy, mostly due to breaking. The theoretical modelling of wave transformation at this site reveals specific distributions of wave heights and bed shear stresses. The sediment borrow areas, presently used and identified for future exploitation, are located inconveniently far from the periodically re-nourished shores. The paper presents the possibilities of dredging works in the coastal zone that would not disturb the natural nearshore motion of water and sediments. The results of the study can be helpful in formulating generic safety standards, at least with respect to dissipative shores of non-tidal or micro-tidal seas, like the Baltic Sea.