Minimum Wave Height Research Articles

Variasi Musiman Tinggi Gelombang Laut Di Perairan Pulau Enggano Provinsi Bengkulu

Enggano Island is one of Indonesia's outermost islands located in the waters west of Sumatra. Enggano Island is directly adjacent to the vast and deep Indian Ocean so that the waters are very dynamic. One of them is known that the sea waves in these waters are very volatile. This study aims to find out the seasonal variation of sea wave height in the waters of Enggano Island, Bengkulu Province. This study uses primary data in the form of sea wave height measured at Kaana Beach and secondary data for 3 years (2021-2023) in the form of monthly average wind direction and speed, temperature and density data obtained from https://data.marine. copernicus.eu/viewer/expert?view=layers&dataset=GLOBAL_ANALYSISFORECAST_PHY_001_024, sea wave height data obtained from https://data.marine.copernicus. eu/viewer/expert?view=layers&dataset=GLOBAL_ANALYSISFORECAST_WAV_001_027. Data processing uses Python Anaconda 3 software for 2D display and Microsoft Excel for time series display. The methods used in this study are descriptive and quantitative methods. The results of the study show that the sea wave height in the waters of Enggano Island varies seasonally, it can be seen that the maximum sea wave height occurs in the eastern season in August with a value of 1.5-3 m with a wind direction and speed of 5-6 m/s and 7 m/s in the southern area of the island, while the minimum wave height occurs in the western season in December with a value of 1-2 m with a wind direction and speed of 1-2 m/s blowing towards the North and West of the island. Keywords : Enggano Island, seasonal variation, high sea waves, wind speed

Sea Wave Energy Simulation of Oscillating Water Column (OWC) Technology, Binongko Island, Wakatobi, Southeast Sulawesi

Indonesia is a country that has the largest sea area of several countries spread across the world. This is an advantage for Indonesia in utilizing the energy potential of the seas and oceans. One of which is the potential of Oscillating Water Column (OWC) Technology, to utilize the energy potential of the seas and oceans not only requires sea potential but also must have location parameters with suitable seabed topography. gentle and constant sea wave height, usually influenced by wind speed. One area of Indonesia that has these parameters is Binongko Island, Wakatobi, Southeast Sulawesi, whose wave characteristics are a basic reference for exploring the enormous energy potential of the seas and oceans in that location. The author uses a simulation model with the Graphical User Interface (GUI) method in the Matlab program to determine the potential energy produced. The data used in this research uses data analysis from the Southeast Sulawesi Regional Meteorology, Climatology, and Geophysics Agency using data samples for 2021 and 2022. The data used includes sea wave height data and sea wave period data at the research location in 2021 and the 2022 time period. Through this data, it is known that Binongko Island, Wakatobi, Southeast Sulawesi 2021 will have minimum sea wave height. of 0.5125 meters and a maximum value of 1.04167 meters, for the minimum sea wave period of 2.34993 seconds and a maximum value of 3.57008 seconds, while in 2022 the minimum sea wave height will be 0.341667 meters and the maximum value will be 0.895833 meters, for a minimum sea wave period of 1.91045 and a maximum value of 3.30481 seconds. With this data, Binongko Island, Wakatobi, Southeast Sulawesi in 2021 will be able to produce a minimum of 20.8844 watts and a maximum of 75.7116 watts, while in 2022 it will be able to produce a minimum of 12.7715 watts and a maximum of 43.5652 watts.

Boulder transport and wave height of a seventeenth-century South China Sea tsunami on Penghu Islands, Taiwan

Abstract. The South China Sea faces widespread tsunami risks from diverse sources, including trench megathrusts, intraplate earthquakes, and landslides. However, historical and geological records to constrain worse-case simulations are scarce. The cliff-top basalt boulders on the Penghu Islands in the Taiwan Strait provide wave estimates from incipient motion formulas and stratigraphic links to the probable sources. Calibrating for ancient local sea levels and a 100-year surge indicates that storm waves in the shallow interisland bathymetry only enable boulder sliding–rolling below the 2.5 m high cliff. A minimum tsunami wave height of ∼ 3.2 m is necessary for cliff-top overflow to exceed boulder height and terminal rolling before deposition. Coeval gravels in two other outcrops also record the time and extent of tsunami deposition with beach-derived bioclasts, stranded pumices, a sharp base, matrix support, poor sorting, and elevations surpassing the 100-year surge. These gravels mark local minimum wave run-ups, reaching 2.4–4.0 m above sea level. The radiocarbon age of the studied boulder, between 1575 and 1706, suggests a probable tie to the disastrous 1661 earthquake in southwest Taiwan and the megathrust source in the northern Manila Trench.

A Novel Rotor Type Wave Energy Converter Design for Maximum Energy Captured in Low Wave Heights

Wave energy converter system (WEC) is generally used by obtaining of electrical energy. Maximise power capture is needed a range of sea-states. Continuity is improved to control of power take off. But wave energy have o lower force and a higher speed in onhore. Therfore, this paper is investigated the novel rotor type wave energy converter performance in this wave suitable conditional. The performance of this system is tested in laboratory condiotions.This aim of design is maximum power absorption from low wave height of waves. Results show that the higher wave height has caused the efficiency to decrease in all periods. The highest efficiency is obtained at a minimum wave height of 2 cm. At this wave height, the efficiency has reached its highest value when the period is 5 s (20.3%). In this case, it makes this prototype suitable for seas with low wave height and high wave period.

Recalculation of minimum wave heights from coastal boulder deposits in the Bristol Channel and Severn Estuary, UK: implications for understanding the high-magnitude flood event of AD 1607

A high-magnitude coastal flood event catastrophically affected the macrotidal Bristol Channel and Severn Estuary in southwest Great Britain, United Kingdom, on 30th January 1607 causing an estimated 2000 fatalities. Historical and physical evidence has provided a basis for the development of a theory that the flood may have been due to a tsunami rather than a storm. Previous studies have collected field data to test this hypothesis including a dataset of 136 wave-transported boulder clasts that was utilised to estimate minimum wave heights through hydrodynamic equations in 2007, but the dataset has hitherto remained unpublished in full. Since 2007 these equations have undergone refinement and for this paper minimum wave heights were recalculated from boulder measurements using revised hydrodynamic equations and presents the complete dataset for the first time. A recent study claiming that such equations are flawed is considered premature, given ongoing refinements to the equations. The results of the present study indicate that a tsunami 4.2 m high can explain the dislodgement of all boulders measured, equivalent to a storm wave height of 16.9 m, which is considerably greater than observed storm wave heights in the region. An up-channel increase in minimum wave height is also suggested by these data, generally corroborating the 2007 study, which may be due to wave amplification caused by the overall funnel-shape of the embayment. The areas worst affected by the 1607 flood are located in the coastal lowlands of the inner Bristol Channel and Severn Estuary, coinciding with the highest minimum estimated wave heights.

Numerical simulations on the fracture of a sea ice floe induced by waves

A three-dimensional dynamic model based on the peridynamics method is developed to simulate the mechanical behavior of sea ice in response to ocean waves. The ice cover is constructed with spherical particles bonded with mechanical bonds, and the fracture can be represented by the sequential failure of mechanical bonds. The thin elastic plate theory is applied to analyze the stress distribution of the ice cover. We analyze the stress distribution and crack propagation path in different cases. A good agreement among numerical model, a viscoelastic model and thin elastic plate model has been obtained on the maximum stress of the ice cover. The maximum stress of the ice cover increases with the increasing of the wave height and the decreasing of the ice thickness. Results reveal that the ratio of ice length to wavelength Li/L and the ice thickness Hi have significant influence on the fracture of sea ice. The minimum wave height to break the ice floe increases with the decreasing of Li/L or the increasing of Hi.

Characteristics of Hydro-Oceanography in the Coastal Waters of Kura-Kura Beach, Bengkayang Regency

The waters of Kura-Kura Beach have quite a lot of human activities, one of which is tourism. The study aims to observe Hydro-Oceanographic parameters such as tidal conditions, ocean currents, and waves. The study uses field observation data and simulation results. The data is calculated to find Formzhal number based on the amplitude of tidal harmonic constants. The Flow analysis to determine the pattern and velocity of the current. The height and period of the wave to analyze characteristics of the wave. The results show that the tide in Kura-Kura Beach waters is a daily mix of a double with the highest tide at MSL and a minimum tide of 0.43 below MSL. While the current velocity obtained from the yield model has a range of (0.003 - 0.11) m/s, and the measurement results are between (0.005 - 0.14) m/s. The simulation results show that the current moves from land to sea at low tide, and it moves from sea to land at toward the tide. For the height of the ocean waves that are formed in a period of 10 years (2009 - 2019) ranges from (0.09 - 154) m and the wave period (1.86 - 5.73) seconds. Based on the calculation results, the largest wave energy occurs in the second intermediate period, namely 184.21 Joules/m with height and wave periods of 1.21 m and 4.39 seconds. In contrast, the smallest wave energy occurs in the first intermediate period with minimum wave height and period 0.18 m and 3.08 seconds. In general, based on the simulation of the current velocity model, the forecasting of wave height and wave energy in Kura-Kura Beach waters is still relatively small. So, it can be concluded that the location is still categorized as safe for coastal tourism and other activities.

Storm-Induced Boulder Displacements: Inferences from Field Surveys and Hydrodynamic Equations

The storm of 12–13 November 2019 provoked the displacements of boulders on a central Mediterranean rocky coast; with reference to a selected area, prone to boulder production and geomorphologically monitored for years, a field-oriented study approach was applied for the phenomenon, by collating data concerning the pre-storm locations and kinematics of these boulders. The number of displaced boulders is 11, that is in terms of the morphological imprint of a specific storm, one of the major study cases for the Mediterranean. In addition, based on widely used hydrodynamic equations, the minimum wave height required to displace the boulders is assessed. The values conform with the expected values for the wave climate dominating during the causative meteorological event and give a measure of the energy of the storm slamming the coast. Boulder dislodgement usually plays a key role in determining the rate of the coastal recession, likely also in the investigated area. In view of an adverse climate evolution with a possible increase of the energy and frequency of severe storms, the results deriving from the study of this morphodynamics should be considered for hazard assessment and coastal management.

TSUNAMI HAZARDS ALONG COASTAL AREA OF WEST KALIMANTAN PROVINCE, INDONESIA

This study aims to simulate tsunami wave heights and their travel time toward the WestKalimantan coastal area. A Nuclear Power Plant (NPP) will be developed in a coastal area in the WestKalimantan Province, Indonesia. The two scenarios of events that may trigger the tsunami waves are volcanicevents caused by Mount Krakatau located in the Sunda Strait and tectonic subduction located at the IndianOcean on the west side of the Sunda Strait. Modeling the tsunami propagation using a finite-element-basedhydrodynamic model developed by the US Army Corps of Engineer, namely the Surface-water ModelingSystem (SMS), is carried out. The model simulates tsunami wave propagation for six alternative locations atthe proposed site of NPP. The model domains consist of Sunda Strait and Karimata Strait domains. The SundaStrait domain model is validated by the observed historical tsunami heights reaching the 12 locations inLampung, Banten, West Java, and Jakarta of Indonesia. The model validations show a good agreement. Thevalidated hydrodynamic model results of the Sunda Strait model are used as the boundary conditions for theKarimata Strait domain model. The Karimata Strait model results show that the peaks of tsunami wave heightsthat reach the western Kalimantan coast are between 12 cm and 116 cm. The minimum wave height peak thatreaches the six prospective locations is 12 cm, which is located in Sambas Regency.

Monitoring the sedimentary budget and dislocated boulders in western Greece – results since 2008

AbstractDislocated boulders are one sign of high‐energy wave impacts on coasts. These high‐energy impacts, caused by severe storms or tsunamis, can trigger initial cracking and transport of boulders. Monitoring of these boulders, as well as the associated coastal sites is important in distinguishing between gradual coastal processes and high‐energy events. Western Greece is a seismically active area, where tsunamis and high‐energetic storms might occur and such past events are documented by historic and geoscientific research, making it an ideal location for monitoring dislocated boulders. Since 2008, monitoring of eight different coastal sites in this region was conducted by terrestrial laser scanning and photogrammetric approaches, with low‐cost unmanned aerial vehicles. The re‐use of similar surveying points in following years, allowed highly accurate monitoring. Point clouds derived from these methods were evaluated for change detection by point cloud comparisons. The data were also used to establish accurate three‐dimensional models of dislocated boulders (n = 70). The determined boulder volumes of these accurate three‐dimensional models were incorporated in wave transport equations and wave decay curves, and compared with monitoring results. A comprehensive overview of dislocated boulders in western Greece is presented. Three‐dimensional boulder reconstruction is compared to an approach which uses a tape‐based measuring of boulder axes, with the tape‐based measurement showing a mean overestimation of mass by 32%. Accurate monitoring over time by both methods, is achieved by using fixed networks of reference points. Changes for each site over time, detected by direct point cloud comparisons, are fit to the possible inundation calculated by wave decay curves based on computed minimum wave heights for boulder transport. Both storm and tsunami waves may have initiated movement from the cliff edge and further transport is also possible. However, boulders showed no further movement from their current position in the area for the time period of this study.

Study on the dependence with the filling level of the sloshing wave pattern in a rectangular tank

This work presents a study of the influence of the filling level on the wave pattern during a sloshing problem. To this end, a rectangular tank of aspect ratio 2:1 is mounted on a shake table subject to controlled external motions. A frequency sweep analysis is performed nearest to the primary resonance frequency using two different amplitudes of imposed motion and different water depths. The wave evolution is registered at certain control points. In particular, this work is devoted to identifying the effect of the filling level on the dynamics of the wave patterns, emphasizing the nonlinearities of the free surface and their dependence on the water depth. The free surface measurements are compared with those obtained from a fixed mesh finite element simulation of the Navier-Stokes equations. The free surface is tracked using a Lagrangian technique. The effect of the bottom boundary conditions on the wave pattern is also evaluated from these simulations. From the experiments, it is confirmed that maximum and minimum wave heights do not change for larger water depth, i.e., when deep water conditions are fulfilled. This fact is also reflected by the numerical results. The computed wave evolution satisfactorily matches the experimental data. In addition, analytical solutions obtained using a potential flow approach are also evaluated. They fail in the description of nonlinear responses, but their coefficients can be numerically or experimentally characterized to fit more realistic solutions.

Study of 3D sloshing in a vertical cylindrical tank

Moving liquid-gas interfaces appear frequently in both natural processes and engineering applications. In the case of partially filled tanks, for instance, the accurate description of the free surface transient behavior during transportation or earthquakes is of paramount importance for structural stability analyses. This work presents new experimental data of sloshing at laboratory scale in a vertical cylindrical tank with different filling levels, along with numerical simulations of selected cases using an open source finite volume application. Maximum and minimum experimental wave heights, measured with ultrasonic sensors, are reported for several non-resonant cases during the periodic steady state regime, along with snapshots of a video recorded near-resonance case. For the numerical simulations, a suitable mesh was designed based on a mesh convergence analysis focused on the simulated velocity profiles at the tank wall. A slight nonlinear behavior is detected in the experimental wave patterns, expressed as non-symmetrical minimum and maximum wave heights. The near-resonance case, in turn, shows a highly three-dimensional behavior of the free surface and a rotational effect. The numerical results obtained for the non-resonant cases show good overall agreement with the experiments, although the non-linear behavior is not accurately modelled. The evolution of the highly distorted free surface in the near-resonance case is well captured by the simulation, along with the observed rotational effect.

Analysis of daily wind circulation toward sea level rise in Semarang

Semarang is one of the coastal areas in Indonesia that frequently occur tidal flood. Tidal flood is a phenomenon where the sea water entering the land area. It can be influenced by astronomical factor that is gravity of moon and sun besides meteorological factor which also play a role in rising the sea level. Sea level rise can cause flood disaster in coastal areas if the height of coastal land is below sea level. At the time of minimum sea wave height, sea level rise is also low, so rising sea level is only played by high tidal fluctuations. Wind data used in this study. The data classified into land breeze, sea breeze and wind transition. From wind data, three classifications of wind speed are determined that is when the wind with minimum, average and maximum speeds. The method of calculating some variables of sea level rise (wave set up) as well as sea tidal observation and measurement. From this research it can be seen that sea level rise in Semarang besides caused by tidal factor is also caused by meteorological factors such as wind speed.

Numerical approach to the study of coastal boulders: The case of Martigues, Marseille, France

The coastal area extending east of the city of Martigues, between the bays of Bonnieu and that of Chariot, is characterized by an alternation of gently sloping rocky coast and 5 m high cliffs composed of Miocene limestone. The foot of the cliff is marked by a well developed notch and a discontinuous wave-cut platform; at its base, the sea bottom reaches a maximum depth of about 4.5–6 m. The emerged area shows boulders placed up to 10 m inland of the coastline at around 2 m above s.l. and, weighing as much as 35 tonnes. A geomorphological survey was conducted by means of a Terrestrial Laser Scanner to estimate boulder sizes. The particular focus of the proposed study was to estimate the minimum wave height required to detach and transport two boulders, originally joined together as one bigger one and weighing approximately 25 tonnes, from the wave-cut platform onto the surf bench. Hydrodynamic models developed by various authors were used to calculate the minimum wave height necessary to move them. The data obtained from the resulting hydrodynamic equations were compared to wave-climate data collected over the last 15 years by the buoy off the coast of Marseille, in the Gulf of Lion. The present study seems to confirm that it would not have been necessary to have a tsunami impact (among other things, never recorded in the last 20 years) to move a 25 tonnes boulder. Indeed, hydrodynamic equations suggest that the boulder might have been broken and only subsequently moved due to the impact of waves generated by an extreme storm which would have occurred prior to December 2003. This hypothesis seems to be in agreement with the morphology of the sea bottom, hydrodynamic features of the area as well as eyewitnesses.

Anchor Strength Analysis for Mooring of a Floating Breakwater in Senoro Field, Central Sulawesi

This paper will describe complete investigations of the analysis anchor strength for mooring of a floating breakwater in Senoro Field. The terminal has berthing facilities located in a water depth about 30 meters, with the wave height of 2.7 meters that made difficult for tanker to berth properly. The requirement for berthing ships must have minimum wave heights of 0.7 meters to 1.5 meters as a requirement [1]. Considering the previously mentioned, a floating breakwater has suggested for reducing wave height. The purpose of this final project is to determine the tension mooring line and anchor pile strength to withstand all possible working loads. Response amplitude operator (RAO) of floating breakwater is used to find the structure characteristic as a response due to wave action. Based on the study, wire rope mooring was chosen due to its safety factor passed API RP 2SK standard, such as the biggest tension is 1389,68 kN on line 1 and the smallest is 1157,72 kN on line 8. Calculate anchor pile strength with three types: spun piles, spun square piles, and triangular piles. Anchor pile could be installed depending on three main factors, uplift capacity, bearing capacity and pile in compression. Based on the analysis, uplift capacity result for pile F is 1960.1 kN, while uplift load result is 1958.47 kN, and pile in compression result is 4155 kN while allowable compression result is 5532 kN. For pile G, uplift capacity result is 1960.7 kN, while uplift load result is 1958.47 kN, and pile in compression result is 4599 kN, while allowable compression result is 7189 kN.

Does Wave Height Matter for Effective Surface Dispersant Application?

ABSTRACTThe Deepwater Horizon (DWH) crude oil release provided an occasion to test the delivery and effectiveness of dispersants on surface oil slicks to reduce the potential exposure of shoreline habitats and marine wildlife to spilled oil. In the beginning of the DWH response, there was concern that the calm sea conditions did not provide sufficient wave energy for dispersant action to occur. At one point a minimum 3-foot wave height requirement for dispersant application was set in an attempt to ensure sufficient mixing energy for dispersant activation was present at the time of application. Because of the ability of aerial dispersant application to rapidly treat large spatial areas and quantities of oil, there was a contrasting concern that a 3-foot (0.91 m) minimum wave height requirement was overly restricting dispersant operations; thereby, increasing environmental exposures.To evaluate the wave heights that effectively dispersed the Macondo crude oil, the SMART (Special Monitoring of Applied Response Technologies) Tier II/III monitoring data of dispersant applications performed in low wave conditions, i.e., < 3 ft (0.91m) were analyzed. Of the 27 SMART Tier II/III monitoring operations conducted in significant wave heights (SWHs) of < 3 feet (0.91 m), 21 were reported as “effective,” 4 were reported as “inconclusive,” and only 2 were reported as “no observed dispersion.” These results demonstrate dispersants were effective in low wave conditions and on weathered Macondo crude oil as a function of distance from the spill site.The paper then estimates the impact that setting wave height restrictions has on dispersant operations showing that a > 3 feet requirement could reduce surface dispersant operational days by as much as 67%. With the dispersant assets available during the DWH response, this could have resulted in leaving up to 700,000 gallons of oil per day on the water,a thus exposing shoreline habitat and offshore wildlife to an increased risk of oiling.The paper concludes thatWave height should not be used as a criterion for approving or conducting surface dispersant application operations, becausewave heights as low as 0.5–1.0 feet were effective in immediately dispersing fresh and weathered Macondo crude oil, and may be sufficient to disperse other oils, andResearch on dispersant application in calm sea conditions has shown that oils would rapidly and almost totally disperse when exposed to breaking waves after being left on a calm water surface for prolonged periods.The paper recommends that government and response organizations should review and consider revising their guidance and operational procedures for dispersant application approval in light of the analysis presented in this paper.

On the displacement of marked pebbles on two coarse-clastic beaches during short fair-weather periods (Marina di Pisa and Portonovo, Italy)

The aim of the investigation was to define the mechanisms of sediment transport in the swash zone of microtidal coarse-clastic beaches in the very short term by evaluating the displacement rates of marked pebbles under low-energy wave conditions. Tests were performed at two sites (Marina di Pisa, Ligurian Sea, and Portonovo, central Adriatic Sea) to check the consistency of the data over a range of different grain sizes. Two recovery campaigns were carried out at both sites, one 6 h and the other 24 h after the injection. During the experiments wave action was at a minimum (wave heights never exceeded 0.3 m). The results show that 20% of pebbles ranging in diameter from 30–90 mm moved significantly (more than 0.5 m) already 6 h after the injection, with some tracers being lost (3%). After 24 h, 40% of the pebbles were significantly displaced and 10% were lost. The preferential downslope movement of tracers, which suggests that coarse sediment movement under low-energy conditions is mainly controlled by gravity processes enhanced by steep beachface slopes, represents the novelty of the results reported here. It would appear that swash processes on low-energy beaches cause a significant rate of pebble displacement through the destabilization induced by wave uprush and backwash. Despite the microtidal range, the position of the mean water level plays a major role in changing the beach level at which swash processes can actually trigger pebble movement. The results of this study show that considerable, and mostly seaward-directed, coarse sediment transport takes place even during short fair-weather periods.

Impact of coastal storms in a sandy barrier (Sancti Petri, Spain)

Benavente, J., Del Rio, L. Plomaritis, T.A, Menapace, W. 2013. Impact of coastal storm in a sandy barrier (Sancti Petri, Spain). In: Conley, D.C., Masselink, G., Russell, P.E. and O’Hare, T.J. (eds.), Proceedings 12 th International Coastal Symposium (Plymouth, England), Journal of Coastal Research, Special Issue No. 65, pp. 666-671, ISSN 0749-0208. Behaviour of sandy geomorphological units under the impact of coastal storms is of great importance when studying coastal evolution in a medium- to short-term scale. In this paper we analyze the effect of storms in determining the recent evolution of Camposoto beach, a sector of Sancti Petri sandspit (Cadiz, SW Spain). Morphological and volumetric changes of washover deposits were evaluated under the effect of coastal storm series recorded during the winter 2009-2010. Several pre- and post-storm topographic surveys of the beach and foredune were performed using an RTK-DGPS, together with a topographic survey of the dune system and the washovers after that winter. The results were compared with dating from the winter 2008-2009, and with a DTM extracted from LIDAR from 2008. Moreover, changes in the area covered by the washover deposits and in the foredune morphology were evaluated by means of GIS tools on aerial photographs from 2008 and 2010. Results showed clear shoreline retreat in the study area, as well as an important impact of the 2009-2010 storm seasons over the foredunes. Changes in the morphology and dimensions of the washovers gave information about the patterns of storm-related medium-term evolution of the system. The above data were used for the calculation of thresholds of the minimum wave height capable of either activating former washover deposits or creating new washovers and foredune retreat. Based on these results we established thresholds for storms generating coastal retreat in the long-term evolution of the sandspit, as a consequence of dune erosion and overwash processes.

Critical storm thresholds for the generation of significant dune erosion at Dziwnow Spit, Poland

Storm influence on the southern Baltic coast was examined for a 14-km long section of the Polish coast along the Dziwnow Spit based on 30years of post-storm dune erosion observations. In this study, we assumed that a significant storm causes noticeable sand dune erosion. Significant changes of the coast after each major storm were analysed based on reports from 1978 to 2008 provided by the Maritime Office, Szczecin. Thirty-two storms that caused dune losses were chosen for analysis. Correlation and hierarchical cluster analysis allowed us to distinguish three groups of storms that caused varying amounts of dune erosion: G1 (small), G2 (medium), and G3 (large). Sea level is the main parameter that influences the amount of dune erosion caused by storms on the southern Baltic coast. Factors such as maximum significant wave height, mean wave direction, storm energy and duration can also, but less significantly, influence dune erosion. The study area was divided into two sections: Dziwnow, where there are many protection measures in place, and Miedzywodzie, which has no protection measures in place. In both areas, we observed differences in the impact of sea level and significant wave height and storm groupings. Approximate minimum sea level and significant wave height thresholds were defined for particular storm groups.

ASSESSMENT OF THE SAFETY OF ULCHIN NUCLEAR POWER PLANT IN THE EVENT OF TSUNAMI USING PARAMETRIC STUDY

Previous evaluations of the safety of the Ulchin Nuclear Power Plant in the event of a tsunami have the shortcoming of uncertainty of the tsunami sources. To address this uncertainty, maximum and minimum wave heights at the intake of Ulchin NPP have been estimated through a parametric study, and then assessment of the safety margin for the intake has been carried out. From the simulation results for the Ulchin NPP site, it can be seen that the coefficient of eddy viscosity considerably affects wave height at the inside of the breakwater. In addition, assessment of the safety margin shows that almost all of the intake water pumps have a safety margin over 2 m, and Ulchin NPP site seems to be safe in the event of a tsunami according to this parametric study, although parts of the CWPs rarely have a margin for the minimum wave height.