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

2021 ◽  
Vol 57 ◽  
pp. 193-206
Author(s):  
Simon K. Haslett ◽  
Bernardine Wong
Keyword(s):  
Wave Height ◽  
Flood Event ◽  
Hydrodynamic Equations ◽  
Severn Estuary ◽  
Wave Amplification ◽  
High Magnitude ◽  
Complete Dataset ◽  
Storm Wave ◽  
Wave Heights ◽  
First Time

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utilised to estimate minimum wave heights through hydrodynamic equations in 2007, but the dataset has hitherto remained unpublished in full.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.

scholarly journals Numerical Simulation of Large Wave Heights from Super Typhoon Nepartak (2016) in the Eastern Waters of Taiwan

2020 ◽  
Vol 8 (3) ◽  
pp. 217 ◽  
Author(s):  
Shih-Chun Hsiao ◽  
Hongey Chen ◽  
Han-Lun Wu ◽  
Wei-Bo Chen ◽  
Chih-Hsin Chang ◽  
...  
Keyword(s):  
Wave Height ◽  
Wind Field ◽  
Outer Region ◽  
Circulation Model ◽  
Large Wave ◽  
Significant Wave ◽  
Hybrid Techniques ◽  
Super Typhoon ◽  
Storm Wave ◽  
Wave Heights

Super Typhoon Nepartak (2016) was used for this case study because it is the most intense typhoon that made landfall in Taiwan in the past decade. Winds extracted from the Climate Forecast System version 2 (CFSV2) and ERA5 datasets and merged with a parametric typhoon model using two hybrid techniques served as the meteorological conditions for driving a coupled wave-circulation model. The computed significant wave heights were compared with the observations recorded at three wave buoys in the eastern waters of Taiwan. Model performance in terms of significant wave height was also investigated by employing the CFSV2 winds under varying spatial and temporal resolutions. The results of the numerical experiments reveal that the simulated storm wave heights tended to decrease significantly due to the lower spatial resolution of the hourly winds from the CFSV2 dataset; however, the variations in the storm wave height simulations were less sensitive to the temporal resolution of the wind field. Introducing the combination of the CFSV2 and the parametric typhoon winds greatly improved the storm wave simulations, and similar phenomena can be found in the exploitation of the ERA5 dataset blended into the parametric wind field. The overall performance of the hybrid winds derived from ERA5 was better than that from the CFSV2, especially in the outer region of Super Typhoon Nepartak (2016).

Hindcasting Hurricane Waves in the Gulf of Mexico

1972 ◽  
Vol 12 (04) ◽  
pp. 321-328 ◽  
Author(s):  
M. M. Patterson
Keyword(s):  
Gulf Of Mexico ◽  
Wave Height ◽  
Wind Field ◽  
Design Theory ◽  
Time History ◽  
Wind Fields ◽  
Platform Design ◽  
Synoptic Wind ◽  
Storm Wave ◽  
Wave Heights

Abstract An estimate of wave heights is needed for risk and venture analysis, for platform design, and for operational planning. Very little reliable data on hurricane waves have been available for a number of years. The present hindcast system uses a moving, two-dimensional wind field to generates and propagate waves to a location of interest. The propagate waves to a location of interest. The wind-wave model is based on work reported in the literature by Wilson. Wave Program I uses a synoptic wind field based on measurements or observations. Wave Program II generates its own wind field based on the track, the time history of the radius to maximum Winds, and the barometric pressure of the storm. Wave Program III also pressure of the storm. Wave Program III also generates its own wind fields, but the storm is moved along a predetermined path. The results of all three hindcast methods have been compared with data gathered from Hurricane Carla. Other hurricanes have also been studied and each of the programs gives comparable results. programs gives comparable results Introduction The most critical environmental factor in deepwater platform design is the selection of wave heights to which the platform will be subjected. Regardless of the design theory, wave loading contributes a major portion of the environmental force on a deep-water platform. To date there has been little sound historical evidence of the magnitude of wave heights that could occur in the Gulf of Mexico. To overcome this problem the offshore oil industry has sought an answer by two related methods. The first method consists of several measuring programs to gather both wave force and wave height information. Since reliable measuring techniques have existed for only a short time, the second method consists of developing techniques to predict historical waves that probably occurred in the Gulf of Mexico. The purpose of this paper is to document Shell's efforts in hindcasting paper is to document Shell's efforts in hindcasting waves for hurricanes that have passed through the Gulf since 1900. In order to hindcast waves, it was necessary to find a mathematical simulation model that would generate waves from a moving wind field. Such wind fields may be taken from synoptic charts or developed from empirical equations based on hurricane data such as radius to maximum winds, central pressure, and forward speed. WAVES FROM A MOVING WIND FIELDTHE BASIC WILSON MODEL Wilson, a consultant in the field of oceanography, has developed a mathematical model that would generate and propagate waves based on a moving wind field. We shall discuss the basic equations for this technique, but shall not go into detail concerning how the equations were developed. INITIATION OF THE WAVE The first wave height generated by a moving wind field can be calculated from Eq. 1 below (1) H1 = 0 .0636U In the above equation Ui is the wind vector in the direction of propagation at time zero and location (x1) where the wave is to start. The distance x1 over which the wave will move is described in Eq. 2. (2) =  0 .761 x1 is the distance the wave travels in nautical miles before it is to be modified by another value of wind velocity. The celerity is defined by Eq. 3. (3) C1  =  2 .498 Finally, the period and wave length of this initial wave are described below. (4) T1  =  C1/3 (5)1 2L1  =  5 .12T SPEJ P. 321

scholarly journals Estimation of Significant Wave Heights from ASCAT Scatterometer Data via Deep Learning Network

2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
He Wang ◽  
Jingsong Yang ◽  
Jianhua Zhu ◽  
Lin Ren ◽  
Yahao Liu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Wave Height ◽  
Significant Wave Height ◽  
Incidence Angle ◽  
Ocean Waves ◽  
Global Scale ◽  
Learning Technology ◽  
Sea State ◽  
Significant Wave ◽  
Wave Heights

Sea state estimation from wide-swath and frequent-revisit scatterometers, which are providing ocean winds in the routine, is an attractive challenge. In this study, state-of-the-art deep learning technology is successfully adopted to develop an algorithm for deriving significant wave height from Advanced Scatterometer (ASCAT) aboard MetOp-A. By collocating three years (2016–2018) of ASCAT measurements and WaveWatch III sea state hindcasts at a global scale, huge amount data points (>8 million) were employed to train the multi-hidden-layer deep learning model, which has been established to map the inputs of thirteen sea state related ASCAT observables into the wave heights. The ASCAT significant wave height estimates were validated against hindcast dataset independent on training, showing good consistency in terms of root mean square error of 0.5 m under moderate sea condition (1.0–5.0 m). Additionally, reasonable agreement is also found between ASCAT derived wave heights and buoy observations from National Data Buoy Center for the proposed algorithm. Results are further discussed with respect to sea state maturity, radar incidence angle along with the limitations of the model. Our work demonstrates the capability of scatterometers for monitoring sea state, thus would advance the use of scatterometers, which were originally designed for winds, in studies of ocean waves.

scholarly journals Intermittent but Rapid Changes to Coastal Landscapes: The Tsunami and El Niño Wave-Formed Sea Arch at Laie Point, Oahu, Hawaii, U.S.A.

Geosciences ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 147
Author(s):  
Benjamin R. Jordan
Keyword(s):  
El Niño ◽  
El Nino ◽  
Sand Dunes ◽  
Tsunami Source ◽  
Tsunami Waves ◽  
Storm Waves ◽  
The Pacific ◽  
Coastal Landscapes ◽  
Wave Heights ◽  
First Time

Kukuiho’olua Island is an islet that lies 164 m due north of Laie Point, a peninsula of cemented, coastal, Pleistocene and Holocene sand dunes. Kukuiho’olua Island consists of the same dune deposits as Laie Point and is cut by a sea arch, which, documented here for first time, may have formed during the 1 April 1946 “April Fools’s Day Tsunami.” The tsunami-source of formation is supported by previous modeling by other authors, which indicated that the geometry of overhanging sea cliffs can greatly strengthen and focus the force of tsunami waves. Additional changes occurred to the island and arch during the 2015–2016 El Niño event, which was one of the strongest on record. During the event, anomalous wave heights and reversed wind directions occurred across the Pacific. On the night of 24–25 February 2016, large storm waves, resulting from the unique El Niño conditions washed out a large boulder that had lain within the arch since its initial formation, significantly increasing the open area beneath the arch. Large waves also rose high enough for seawater to flow over the peninsula at Laie Point, causing significant erosion of its upper surface. These changes at Laie Point and Kukuio’olua Island serve as examples of long-term, intermittent change to a coastline—changes that, although infrequent, can occur quickly and dramatically, potentially making them geologic hazards.

scholarly journals Wave Height Distributions and Rogue Waves in the Eastern Mediterranean

2021 ◽  
Vol 9 (6) ◽  
pp. 660
Author(s):  
Sagi Knobler ◽  
Daniel Bar ◽  
Rotem Cohen ◽  
Dan Liberzon
Keyword(s):  
Wave Height ◽  
Eastern Mediterranean ◽  
Rogue Waves ◽  
Distribution Model ◽  
Storm Events ◽  
Order Model ◽  
Deep Seawater ◽  
Wave Heights ◽  
Storm Characteristics ◽  
Buoy Data

There is a lack of scientific knowledge about the physical sea characteristics of the eastern part of the Mediterranean Sea. The current work offers a comprehensive view of wave fields in southern Israel waters covering a period between January 2017 and June 2018. The analyzed data were collected by a meteorological buoy providing wind and waves parameters. As expected for this area, the strongest storm events occurred throughout October–April. In this paper, we analyze the buoy data following two main objectives—identifying the most appropriate statistical distribution model and examining wave data in search of rogue wave presence. The objectives were accomplished by comparing a number of models suitable for deep seawater waves. The Tayfun—Fedele 3rd order model showed the best agreement with the tail of the empirical wave heights distribution. Examination of different statistical thresholds for the identification of rogue waves resulted in the detection of 99 unique waves, all of relatively low height, except for one wave that reached 12.2 m in height which was detected during a powerful January 2018 storm. Characteristics of the detected rogue waves were examined, revealing the majority of them presenting crest to trough symmetry. This finding calls for a reevaluation of the crest amplitude being equal to or above 1.25 the significant wave height threshold which assumes rogue waves carry most of their energy in the crest.

scholarly journals Historical variation and trends in storminess along the Portuguese South Coast

2011 ◽  
Vol 11 (9) ◽  
pp. 2407-2417 ◽  
Author(s):  
L. P. Almeida ◽  
Ó. Ferreira ◽  
M. I. Vousdoukas ◽  
G. Dodet
Keyword(s):  
Wave Height ◽  
Linear Increase ◽  
Annual Number ◽  
The North ◽  
Storm Wave ◽  
Using Data ◽  
The North Atlantic Oscillation ◽  
Historical Variation ◽  
Storm Characteristics ◽  
South Portugal

Abstract. This work investigates historical variation and trends in storm climate for the South Portugal region, using data from wave buoy measurements and from modelling, for the period 1952 to 2009. Several storm parameters (annual number of storms; annual number of days with storms; annual maximum and mean individual storm duration and annual 99.8th percentile of significant wave height) were used to analyse: (1) historical storminess trends; (2) storm parameter variability and relationships; and (3) historical storminess and its relationship to the North Atlantic Oscillation (NAO). No statistically significant linear increase or decrease was found in any of the storm parameters over the period of interest. The main pattern of storm characteristics and extreme wave heights is an oscillatory variability with intensity peaks every 7–8 yr, and the magnitude of recent variations is comparable with that of variations observed in the earlier parts of the record. In addition, the results reveal that the NAO index is able to explain only a small percentage of the variation in storm wave height, suggesting that more local factors may be of importance in controlling storminess in this region.

Development of Operational Limit Diagrams for Offshore Lifting Procedures

2015 ◽  
Author(s):  
Leonardo Roncetti ◽  
Fabrício Nogueira Corrêa ◽  
Carl Horst Albrecht ◽  
Breno Pinheiro Jacob
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Technological Development ◽  
Automatic Generation ◽  
Dynamic Responses ◽  
Offshore Platforms ◽  
Peak Period ◽  
Significant Wave ◽  
Wave Heights ◽  
Offshore Crane

Lifting operations with offshore cranes are fundamental for proper functioning of a platform. Despite the great technological development, offshore cranes load charts only consider the significant wave height as parameter of environmental load, neglecting wave period, which may lead to unsafe or overestimated lifting operations. This paper aims to develop a method to design offshore crane operational limit diagrams for lifting of personnel and usual loads, in function of significant wave height and wave peak period, using time domain dynamic analysis, for a crane installed on a floating unit. The lifting of personnel with crane to transfer between a floating unit and a support vessel is a very used option in offshore operations, and this is in many cases, the only alternative beyond the helicopter. Due to recent fatal accidents with lifting operations in offshore platforms, it is essential the study about this subject, contributing to the increase of safety. The sea states for analysis were chosen covering usual significant wave heights and peak periods limits for lifting operations. The methodology used the SITUA / Prosim software to obtain the dynamic responses of the personnel transfer basket lifting and container loads on a typical FPSO. Through program developed by the author, it was implemented the automatic generation of diagrams as a function of operational limits. It is concluded that using this methodology, it is possible to achieve greater efficiency in the design and execution of personnel and routine load lifting, increasing safety and a wider weather window available.

A Method to Implement the Random Signals for Time Varying Offshore Wave Height During Storm Condition in an Intra-Wave Period Wave Model

2006 ◽  
Author(s):  
Yuliang Zhu ◽  
Shunqi Pan ◽  
Premanandan T. Fernando ◽  
Xiaoyan Zhou
Keyword(s):  
Wave Height ◽  
Wave Model ◽  
Peak Frequency ◽  
Wave Period ◽  
Storm Event ◽  
Time Varying ◽  
Wave Heights ◽  
Offshore Wave ◽  
Storm Condition ◽  
Period Wave

In this paper, a method to implement the surface elevation at the offshore boundary during storm conditions is presented in the intra-wave period wave model. At storm condition, the offshore incident significant wave height is time varying. In the case of time varying incident wave height, the JONSWAP energy spectrum can be manipulated as follows: H1/32s(f). s(f) is the energy density function for a unit wave height. During a storm event not only the offshore boundary significant wave heights but also the peak frequency varies. If we choose a mean peak frequency during a storm event, s(f) can be calculated for the mean peak frequency for the storm event. The amplitudes of the component waves for the random signals are calculated from the unit energy density function s(f), and the phase angle of the component wave, So we can numerically generate surface elevation time series for the time varying offshore wave heights. The method was verified in the intra-wave period wave model using field measurements at Sea Palling site Norfolk UK.

scholarly journals ANALISA TITIK KRITIS GERAKAN ROLL KAPAL TRIMARAN UNTUK DIAPLIKASI PADA KAPAL IKAN PURSE SEINE

2021 ◽  
Vol 4 ◽  
pp. 44-50
Author(s):  
Fella Gaspersz ◽  
Richard B. Luhulima
Keyword(s):  
Critical Point ◽  
Wave Height ◽  
Inclination Angle ◽  
Weather Conditions ◽  
Extreme Weather ◽  
Roll Motion ◽  
Fishing Vessel ◽  
Fishing Vessels ◽  
Wave Heights ◽  
Wave Angle

The marine fisheries catching and processing industry are considered vulnerable to the effects of extreme weather at sea. Global warming effects and El Nino and La Nina have a significant impact on the upwelling process, which impacts the lifestyle and environment of marine biota, including pelagic fish, which is one of the most important contributors to the shipping industry. Extreme weather conditions, with wave heights ranging from 1 to 5 meters, dominate the waters of Maluku. In extreme sea conditions, most fishers choose not to go fishing, not because there are no fish at the fishing grounds, but to avoid mishaps at sea. This research aimed to analyze the critical point of ship roll motion and ship stability. The hull shape employed in this study was a monohull fishing vessel and a trimaran fishing vessel with the same displacement of 21,1 tons. In extreme weather conditions, the Maxsurf software was used to analyze the ship's response, especially the critical point of the ship's roll motion. The I.M.O. Standard was utilized to calculate the ship's stability. The operational speed of the ship was v = 3 knots, with fluctuations in wave angle of incidence between 00 - 1800. Wave heights of 1,0; 2,0; 3,0, and 0,4 meters represent extreme weather conditions in Maluku waters' fishing grounds. The findings revealed that the trimaran hull type had better stability where the inclination angle of trimaran vessel stability was 480 while the monohull was 410. The trimaran fishing vessel was able to withstand a wave height of 3 meters with an inclination angle of 32,560. In comparison, the monohull fishing vessel was able to survive at a wave height of 2 meters with an inclination angle of 24,690. Monohull fishing vessel had a maximum limit of roll motion at wave directions 82 and 99 with a wave height of 3 m, and it reached at the critical point at angles of 43 and 138, at the height of 4 m. Meanwhile, the trimaran fishing vessel had a critical point at a wave angle of 760 and 1000 with a wave height of 4 meters. In the area between those two angles, monohull and trimaran fishing vessels will lose the balance (stability) of the roll motion, resulting in capsize.

scholarly journals MACH-REFLECTION AS A DIFFRACTION PROBLEM

1976 ◽  
Vol 1 (15) ◽  
pp. 45 ◽  
Author(s):  
Udo Berger ◽  
Soren Kohlhase
Keyword(s):  
Wave Height ◽  
Incident Wave ◽  
Water Waves ◽  
Gas Dynamics ◽  
Mach Reflection ◽  
Diffraction Problem ◽  
Vertical Wall ◽  
Oblique Wave ◽  
Wave Heights ◽  
The Waves

As under oblique wave approach water waves are reflected by a vertical wall, a wave branching effect (stem) develops normal to the reflecting wall. The waves progressing along the wall will steep up. The wave heights increase up to more than twice the incident wave height. The £jtudy has pointed out that this effect, which is usually called MACH-REFLECTION, is not to be taken as an analogy to gas dynamics, but should be interpreted as a diffraction problem.

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