scholarly journals Extreme waves at Filyos, southern Black Sea

2011 ◽  
Vol 11 (3) ◽  
pp. 659-666 ◽  
Author(s):  
E. Bilyay ◽  
B. O. Ozbahceci ◽  
A. C. Yalciner
Keyword(s):  
Black Sea ◽  
Rayleigh Distribution ◽  
Height Distribution ◽  
Extreme Waves ◽  
Black Sea Region ◽  
Average Value ◽  
Wave Measurement ◽  
Wave Height Distribution ◽  
Current Interaction ◽  
Surface Profiles

Abstract. A wave measurement project was carried out for a new port planned in Filyos, in the Western Black Sea region of Turkey. The measurement at a depth of 12.5 m lasted for a period of two years and 7949 records were obtained. During the analysis, it was noticed that there were 209 records in which H/Hs ratio was higher than 2.0. These higher waves in a record are called extreme waves in this study. Although the purpose of wave measurement is not to investigate extreme waves, it is believed that studying these unexpected waves could be interesting. Therefore, detailed statistical and spectral analyses on the extreme waves were done for the records. The analyses results show that the distribution of surface profiles of the records containing extreme waves deviates from Gaussian distribution with the negative skewness changing between –0.01 and –0.4 and with the high kurtosis in the range of 3.1–4.2. Although the probability of occurrence of the extreme waves is over-predicted by the Rayleigh distribution, a higher ratio of Hs/ηrms indicates that the wave height distribution can be represented by Rayleigh. The average value of the slope of the frequency spectrum at the high frequency range is proportional to f–9 which is much steeper than the typical wind-wave frequency power law, f–4, –5. The directional spreading is measured with the parameter Smax and it is in the range of 5–70 for the extreme wave records. The wave and current interaction was also investigated and it was found that in most cases, extreme waves occur when the wave and the current are almost aligned. Furthermore, it is observed that extreme waves appear within a group of high waves.

scholarly journals The Amount and Distribution of the Red Data Book Bird Wetland Species in the Azov-Black Sea Region of Ukraine According to the Results of August Counts 2004–2015

2018 ◽  
Vol 52 (2) ◽  
pp. 145-154 ◽  
Author(s):  
J. I. Chernichko ◽  
V. A. Kostiushyn ◽  
S. V. Vinokurova
Keyword(s):  
Black Sea ◽  
Coastal Wetlands ◽  
Black Sea Region ◽  
Average Value ◽  
Red Data Book ◽  
Black Sea Coast ◽  
Data Book ◽  
Water Birds ◽  
Local Water ◽  
Total Average

Abstract In the period from 2004 to 2015, in the Azov-Black Sea region of Ukraine and the adjacent territories five simultaneous August Counts covered all key coastal wetlands were conducted. They were primarily aimed at studying the abundance and spatial distribution of local water birds fauna, since that time there was hardly any migrations. In total 5.5 million birds of 133 species were counted during five August Counts. Forty species of them are included in the 3rd edition of the Red Data Book (RDB) of Ukraine, 35 of which are ecologically related to wetlands. The total amount of RDB birds was 179.5 thousand individuals, or 3.26 % of the total number of counted birds. Amount of birds varied from count to count between 21 and about 55 thousands of birds. In total 80 wetlands were covered by surveys, and in 73 of them (91.3 %), at least one time RDB species were recorded, that indicates the importance of the Azov-Black Sea coast for maintaining both local and migratory RDB birds. In five of the most valuable wetlands the percentage of counted birds from the total average value for all birds ranged from 5.3 % to 16.7 %, cumulatively making up 49.3 %. These are the following sites — Eastern Sivash, Lower part of the Ukrainian Danube Delta, Central Syvash, Kinburnskyi Peninsula, Lebedyni Islands.

New Insights in Extreme Crest Height Distributions: A Summary of the ‘CresT’ JIP

2011 ◽  
Author(s):  
Bas Buchner ◽  
George Forristall ◽  
Kevin Ewans ◽  
Marios Christou ◽  
Janou Hennig
Keyword(s):  
Single Point ◽  
Field Measurements ◽  
Order Theory ◽  
Second Order ◽  
Wave Crest ◽  
Height Distribution ◽  
Extreme Waves ◽  
Wave Height Distribution ◽  
Floating Platforms ◽  
Crest Height

The objective of the CresT JIP was ‘to develop models for realistic extreme waves and a design methodology for the loading and response of floating platforms’. Within this objective the central question was: ‘What is the highest (most critical) wave crest that will be encountered by my platform in its lifetime?’ Based on the presented results for long and short-crested numerical, field and basin results in the paper, it can be concluded that the statistics of long-crested waves are different than those of short-crested waves. But also short-crested waves show a trend to reach crest heights above second order. This is in line with visual observations of the physics involved: crests are sharper than predicted by second order, waves are asymmetric (fronts are steeper) and waves are breaking. Although the development of extreme waves within short-crested sea states still needs further investigation (including the counteracting effect of breaking), at the end of the CresT project the following procedure for taking into account extreme waves in platform design is recommended: 1. For the wave height distribution, use the Forristall distribution (Forristall, 1978). 2. For the crest height distribution, use 2nd order distribution as basis. 3. Both the basin and field measurements show crest heights higher than predicted by second order theory for steeper sea states. It is therefore recommended to apply a correction to the second order distribution based on the basin results. 4. Account for the sampling variability at the tail of the distribution (and resulting remaining possibility of higher crests than given by the corrected second order distribution) in the reliability analysis. 5. Consider the fact that the maximum crest height under a complete platform deck can be considerably higher than the maximum crest at a single point.

Dependence of Shape Parameter of Weibull Distribution on Wave Spectral Width and Nonlinearity

2008 ◽  
Author(s):  
Changliang Li ◽  
Bingchen Liang ◽  
Lin Zhao
Keyword(s):  
Weibull Distribution ◽  
Wave Height ◽  
Shape Parameter ◽  
Wave Train ◽  
Spectral Width ◽  
Rayleigh Distribution ◽  
Height Distribution ◽  
Irregular Wave ◽  
Wave Height Distribution ◽  
Ocean Environment

In practice, the wave height distribution associated with an irregular wave train is always mathematically modeled as a Rayleigh distribution. However, the realistic ocean wave height distribution might deviate from a Rayleigh distribution. The present study demonstrates that a better mathematical model for wave height distribution under realistic ocean environment is a Weibull distribution. In comparison with a Rayleigh distribution, a Weibull distribution has the flexibility on choosing its “shape parameter”. According to the nonlinear Monte Carlo simulations, this study investigates the nonlinearity and spectral width effects on the shape parameter for the Weibull wave height distribution. A new empirical formula for calculating the shape parameter is proposed, which can be used easily in application.

scholarly journals WAVE HEIGHT DISTRIBUTION IN CONSTANT AND FINITE DEPTHS

2012 ◽  
Vol 1 (33) ◽  
pp. 15 ◽  
Author(s):  
Sofia Caires ◽  
Marcel R.A. Van Gent
Keyword(s):  
Shallow Water ◽  
Wave Height ◽  
Wave Breaking ◽  
Rayleigh Distribution ◽  
Height Distribution ◽  
High Wave ◽  
Wave Height Distribution ◽  
Individual Wave ◽  
Wave Heights

Several alternatives to the Rayleigh distribution have been proposed for describing individual wave heights in regions where depth-induced wave breaking occurs. The most widely used of these is the so-called Battjes and Groenendijk distribution. This distribution has been derived and validated in a context of a shallow water foreshore waves propagating over a gently sloping shallow region towards the shore. Its validity for waves propagating in regions with shallow flat bottoms is investigated here. It is concluded that the distribution on average underestimates (outside its range of validity) high wave height measurements in shallow flat bottoms by as much as 15%.

scholarly journals WAVE HEIGHT DISTRIBUTION OF WIND WAVES OVER LONG WAVES

1976 ◽  
Vol 1 (15) ◽  
pp. 21
Author(s):  
Shan-Hwei Ou ◽  
Frederick L.W. Tang
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Wind Wave ◽  
Wind Waves ◽  
Rayleigh Distribution ◽  
Long Waves ◽  
Height Distribution ◽  
Long Wave ◽  
Wave Height Distribution ◽  
Wave Generator

Influence of long wave on the wave height distribution of wind waves was studied through the laboratory experiment. Experiments were conducted in a wind-wave tank where the wind waves were generated by a wind blower and the long waves were developed by an oscillating pendulum type wave generator. The wave height distribution of the wind waves over long wave is slightly different from the Rayleigh distribution in the small steepness of long wave. The ratios between the average of highest l/n-th waves vary with the steepness of long waves. The magnitude and the location of the spectral peak of wind waves are altered. The amount of the attenuation of wind wave energy is larger than the results of Mitsuyasu (1966).

Numerical Validation of the Goda Spread Parameter of Extreme Wave Height Distribution

2007 ◽  
Author(s):  
G. Benassai ◽  
E. Chianese
Keyword(s):  
Wave Height ◽  
Height Distribution ◽  
Tyrrhenian Sea ◽  
Spatial Homogeneity ◽  
Wave Measurement ◽  
Wave Height Distribution ◽  
Southern Tyrrhenian Sea ◽  
Definition Of ◽  
Homogeneity Hypothesis ◽  
Sea Area

Starting from the definition of the Goda spread parameter γ50 and from the verification of the spatial homogeneity hypothesis, the 50-year significant wave height H50 was obtained for a sea area characterized by a limited wave observation period. The procedure was applied for the location of Cetraro in the Southern Tyrrhenian Sea starting from the waves recorded offshore Ponza, provided that the spatial homogeneity hypothesis was verified. This hypothesis was not verified, however, between the wave measurement stations of Crotone or Catania and two wave measurement stations recently installed by Calabria Region in the Ionian Sea. In the Southern Tyrrhenian Sea the results of H50 were compared with the ones obtained with the method of fetch transposition of De Girolamo & Contini (1998).

scholarly journals PARAMETRIC REPRESENTATION OF A WIND-WAVE FIELD

1976 ◽  
Vol 1 (15) ◽  
pp. 11 ◽  
Author(s):  
Henrik Rye ◽  
Roald Svee
Keyword(s):  
Wave Field ◽  
Field Data ◽  
Wind Wave ◽  
Parametric Representation ◽  
Rayleigh Distribution ◽  
Spectral Shape ◽  
Height Distribution ◽  
Shape Parameters ◽  
Wave Parameters ◽  
Wave Height Distribution

The applicability of various spectral shape parameters is discussed. The wave .height distribution from 60 actual wave recordings is computed and compared to the Rayleigh distribution. The behaviour of various wave period parameters is discussed. Based on results from field data as well as numerical computations, it is concluded that some of the spectral wave parameters frequently used today may not be suitable for characterizing the wave field.

scholarly journals A COASTAL AREA MODEL CONSIDERING WAVE-CURRENT INTERACTION AND ITS APPLICATION TO WIDE-CRESTED SUBMERGED BREAKWATER

2012 ◽  
Vol 1 (33) ◽  
pp. 12
Author(s):  
Masamitsu Kuroiwa ◽  
Ahmed Khaled Seif ◽  
Yuhei Matsubara ◽  
Yasushi Ichimura ◽  
Hajime Mase ◽  
...  
Keyword(s):  
Predictive Model ◽  
Balance Equation ◽  
Coastal Area ◽  
Artificial Reefs ◽  
Height Distribution ◽  
Rip Currents ◽  
Submerged Breakwater ◽  
Wave Height Distribution ◽  
Scour Hole ◽  
Current Interaction

This study is concerned with development of a 3D morphodynamic predictive model for considering wave-current interaction by using wave action balance equation. The developed model was applied to model tests associated with a detached breakwater and wide-crested submerged breakwaters, and the influences of strong currents around the structures into wave height distribution and bathymetry change were investigated. Furthermore, the morphodynamics around the artificial reefs in the Uradome Beach, Tottori, Japan, was computed. From the computed results, a large scour hole due to strong rip-currents in the opening of the reefs was reproduced. The applicability of the model was confirmed.

scholarly journals SEISMICITY of the CRIMEAN-BLACK SEA REGION in 2015

2021 ◽  
pp. 43-49
Author(s):  
V. Svidlova ◽  
M. Bondar
Keyword(s):  
Black Sea ◽  
Seismic Energy ◽  
Observation Point ◽  
Maximum Density ◽  
The Black Sea ◽  
Focal Mechanism Solution ◽  
Black Sea Region ◽  
Average Value ◽  
Area 5 ◽  
Observation Period

In 2015, 58 earthquakes were registered in Crimea in the range of energy classes КП=5.2–10.8. The bulk of the epicenters refers to the Black Sea. The maximum density of epicenters can be traced in Alushta (№ 3) area and in the Kerch-Anapa area (№ 5). Spectral and dynamic parameters of their foci were obtained for 16 events in the region; and for 1 of them a focal mechanism solution was obtained. Seismic processes in the Crimean-Black Sea region were monitored by seven stationary digital seismic stations. In February, the «Tarkhankut» observation point was closed. Representative registration of earthquakes with Кп=9.0 is still provided for main part of the Crimean-Black Sea region. A peculiarity of spatial distribution of earthquakes is the occurrence of two strongest earthquakes in the year under consideration with КП=10.8 in the Kerch-Anapa (№ 5) and Azovo-Kuban (№ 7) areas. The maximum (Кп=10.8, MLWSG=3.8, Mw=3.8) earthquake occurred on August 16 at 22h38m in the Kerch-Anapa region at the depth of h=7 km. This shock caused tremors in Anapa with the intensity of I=2 according the MSK-64 scale. 2015 is characterized by weak seismic activity. The total number of registered earthquakes, ΣN=58, decreased against ΣN=119 in 2014 and is below than the average Nav=69 for the ten-year observation period (2004–2013). The annual seismic energy is ΣE=1.491011J, that is 5.6 times less than the average value ΣEav=8.41011J for the ten-year period. This suggests that we can expect increased seismicity in the region in subsequent years.

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