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1
Content available remote Dependence of acoustic noise emission on the dissipated energy of plunging waves
Klusek Zygmunt, Paprota Maciej, Sulisz Wojciech, Zdolska Aneta, Sorek Sebastian
Oceanologia
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2020
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No. 62 (1)
70--82
EN
The results of experiments performed in a wave flume designed to explore associations between the dissipation of surface wave energy during breaking and acoustic noise emission are presented. The experiments were carried out using tap water in the wave laboratory of the Institute of Hydro-Engineering of the Polish Academy of Sciences, Gdańsk, Poland. In particular, being shown are the parameters of empirical dependency between the dissipated wave energy during plunging and the energy of pre-breaking wave trains. Relationships between wave energy losses in the case of breakers with an amplitude of about 10 cm and the noise acoustic energy in the frequency band from 80 to 12,500 Hz were estimated. Taking into consideration the phenomena of reverberations and propagation in an acoustical waveguide, a numerical model was used for the correction of the observed noise's acoustic spectra. A detailed analysis of the factors affecting the noise level in the semi-enclosed volume allowed us to specify the rate of conversion of the wave energy dissipated during breaking into acoustic energy, which was found to be in the order of 10−8.
2
Content available remote Some characteristic wave energy dissipation patterns along the Polish coast
Różyński G., Szmytkiewicz P.
Oceanologia
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2018
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No. 60 (4)
500--512
EN
The paper analyses cross-shore bathymetric profiles between Władysławowo (km 125 of the national coastal chainage) and Lake Sarbsko (km 174) commissioned in 2005 and 2011 by coastal authorities for monitoring purposes. The profiles, spaced every 500 m, cover beach topography from dune/cliff tops through the emerged beach to a seabed depth of about 15 m. They were decomposed by signal processing techniques to extract their monotonic components containing all major modes of the variability of beach topography. They are termed empirical equilibrium profiles and can be used for straightforward assessment of wave energy dissipation rates. Three characteristic patterns of wave energy dissipation were thus identified: one associated with large nearshore bars and several zones of wave breaking; a second, to which the equilibrium beach profile concept can be applied; and a third, characterized by mixed behaviour. Interestingly, most profiles showed significant seabed variations beyond the nearshore depth of closure – this phenomenon requires comprehensive studies in future.
3
Content available Local Wave Energy Dissipation and Morphological Beach Characteristics along a Northernmost Segment of the Polish Coast
Różyński G.
Archives of Hydro-Engineering and Environmental Mechanics
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2018
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Vol. 65, nr 2
91--108
EN
This paper analyses cross-shore bathymetric profiles between Władysławowo (km 125 of the Polish coastal chainage) and Lake Sarbsko (km 174) done in 2005 and 2011. Spaced every 500 m, they cover beach topography from dune/cliff crests to a seabed depth of about 15 m. They were decomposed by signal processing techniques to extract the monotonic component of beach topography and to perform a straightforward assessment of wave energy dissipation rates. Three characteristic dissipation patterns were identified: one associated with large nearshore bars and 2–3 zones of wave breaking; a second, to which the equilibrium beach profile concept can be applied; and a third, characterized by mixed behaviour. An attempt was then made to interpret these types of wave energy dissipation in terms of local coastal morphological features and the underlying sedimentary characteristics.
4
Content available Wave transformation in a multi-bar surf zone: case study of Lubiatowo (Poland)
Lan Y. J., Hsu T. W., Ostrowski R., Szmytkiewicz M.
Archives of Hydro-Engineering and Environmental Mechanics
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2016
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Vol. 63, nr 1
19--34
EN
The paper presents results of field and theoretical investigations of wave transformation in the surf zone near the IBW PAN Coastal Research Station in Lubiatowo (Poland, the south Baltic Sea). The study site displays multi-bar cross-shore profiles that intensively dissipate wave energy, mostly induced by breaking. The main field data comprise wave heights and cross-shore bathymetric profiles. Wave transformation is modelled theoretically by two approaches, namely the IBW PAN phase-averaged wave transformation model and the approach based on the hydraulic jump model, developed by Hsu & Lai (2009) for hydrological situations encountered under the actual conditions of two field campaigns – in 1987 and 1996. Discrepancies between the measured data and the model results are discussed. In general, the model results are in good agreement with the in-situ observations. The comparison of the field data with the computational results concerns a part of the surf zone between about 5 m water depth and the first nearshore stable bar, where the depth amounts to ca. 1.2 m.
5
Content available 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.
6
Content available remote Acoustic noise generation under plunging breaking waves
Klusek Z., Lisimenka A.
Oceanologia
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2013
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No. 55 (4)
809--836
EN
The paper presents results of investigations performed in a wave channel in order to determine associations between the dissipation of surface wave energy during breaking and acoustic noise emission. The experiments were carried out in fresh water in the Large Wave Flume (GWK) at the Forschungszentrum Küste (FZK) in Hanover (Germany). Relationships between the acoustic noise energy and losses of surface wave energy were estimated over the broad acoustic frequency band from 350 to 12 500 Hz, and the characteristic temporal changes of the spectral properties of noise in the breaking process were demonstrated. It was found that the ratio of acoustic noise energy generated during wave breaking to the energy dissipation of single plunging breakers with heights of 1.6-2.8 m were in the 10-9- 10-8 range and found to be in reasonable agreement with the results of some previous experiments performed for smaller scales of breaking wave. The study contributes to the development of a passive acoustic method for the parameterization of sea surface dynamic processes.
7
Content available remote Variability and correlations of shoreline and dunes on the southern Baltic coast (CRS Lubiatowo, Poland)
Pruszak Z., Ostrowski R., Schönhofer J.
Oceanologia
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2011
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No. 53 (1)
97-120
EN
The paper analyses the results of field investigations into the evolution of the shoreline and dune toe positions in a multi-bar, dissipative coastal zone. The correlations between the changes in the shoreline and the dune toe range from -0.4 to 0.8. It is most often the case that the dune toe is stable while the shoreline moves. Consistent cross-shore migration is slightly more likely to happen than the divergent or convergent movements of both lines. Shoreline retreat and advance attain respective rates of 0.7 m day-1 and 0.4 m day-1. Deep-water wave energy of about 50 kJ m-1 constitutes the boundary between shore accumulation and erosion.
8
Content available remote Shallow-water wave energy dissipation in a multi-bar coastal zone
Pruszak Z., Szmytkiewicz P., Ostrowski R., Skaja M., Szmytkiewicz M.
Oceanologia
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2008
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No. 50 (1)
43-58
EN
The paper presents the results of studies of wave transformation on a multi-bar cross-shore profile of the southern Baltic Sea. The field investigations of wave motion were carried out using an offshore wave buoy and string wave gauges at the IBW PAN Coastal Research Station, Lubiatowo (Poland). These experimental results were used to validate statistical relationships between characteristic wave parameters in the coastal region and to assess wave energy dissipation in the surf zone. A simple model for calculating the residual nearshore wave energy is proposed and tested versus the data collected in situ.
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