scholarly journals Boulder accumulations related to extreme wave events on the eastern coast of Malta

2015 ◽  
Vol 3 (10) ◽  
pp. 5977-6019 ◽  
Author(s):  
S. Biolchi ◽  
S. Furlani ◽  
F. Antonioli ◽  
N. Baldassini ◽  
J. Causon Deguara ◽  
...  
Keyword(s):  
Eastern Coast ◽  
Hydrodynamic Equations ◽  
Storm Events ◽  
Sea Waves ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Storm Waves ◽  
Hellenic Arc ◽  
Intense Storm ◽  
Wave Heights

Abstract. The accumulation of large boulders related to waves generated either by tsunamis or extreme storm events has been observed in different areas of the Mediterranean Sea. Along the NE and E low-lying rocky coasts of Malta tens of large boulder deposits have been surveyed, measured and mapped. These boulders have been detached and moved from the seafloor and lowest parts of the coast by the action of sea waves. In the Sicily–Malta channel, heavy storms are common and originate from the NE and NW winds. Conversely, few severe earthquakes and tsunamis are recorded in historical documents to have hit the Maltese archipelago, originated by seismicity activity related mainly to the Malta Escarpment, the Sicily Channel Rift Zone and the Hellenic Arc. We present a multi-disciplinary study, which aims to define the characteristics of the boulder accumulations along the eastern coast of Malta, in order to assess the coastal geo-hazard implications triggered by the sheer ability of extreme waves to detach and move large rocky blocks inland. The wave heights required to transport coastal boulders were calculated using various hydrodynamic equations. Particular attention was devoted to the quantification of the input parameters required in the workings of these equations. The axis sizes of blocks were measured with 3-D digital photogrammetric techniques and their densities were obtained throughout the use of a N-type Schmidt Hammer. Moreover, AMS ages were obtained from selected marine organisms encrusted on some of the boulders in various coastal sites. The combination of the results obtained by hydrodynamic equations and the radiocarbon dating suggests that the majority of the boulders has been detached and moved by intense storm waves. Nonetheless, it is possible that some of them may have been transported by tsunami.

scholarly journals Boulder accumulations related to extreme wave events on the eastern coast of Malta

2016 ◽  
Vol 16 (3) ◽  
pp. 737-756 ◽  
Author(s):  
Sara Biolchi ◽  
Stefano Furlani ◽  
Fabrizio Antonioli ◽  
Niccoló Baldassini ◽  
Joanna Causon Deguara ◽  
...  
Keyword(s):  
Radiocarbon Dating ◽  
Marine Organisms ◽  
Eastern Coast ◽  
Hydrodynamic Equations ◽  
Storm Events ◽  
Storm Waves ◽  
Intense Storm ◽  
Wave Heights ◽  
The Mediterranean ◽  
Very High

Abstract. The accumulation of large boulders related to waves generated by either tsunamis or extreme storm events have been observed in different areas of the Mediterranean Sea. Along the eastern low-lying rocky coasts of Malta, five sites with large boulder deposits have been investigated, measured and mapped. These boulders have been detached and moved from the nearshore and the lowest parts of the coast by sea wave action. In the Sicily–Malta channel, heavy storms are common and originate from the NE and NW winds. Conversely, few tsunamis have been recorded in historical documents to have reached the Maltese archipelago. We present a multi-disciplinary study, which aims to define the characteristics of these boulder accumulations, in order to assess the coastal geo-hazard implications triggered by the sheer ability of extreme waves to detach and move large rocky blocks inland. The wave heights required to transport 77 coastal boulders were calculated using various hydrodynamic equations. Particular attention was given to the quantification of the input parameters required in the workings of these equations, such as size, density and distance from the coast. In addition, accelerator mass spectrometry (AMS) 14C ages were determined from selected samples of marine organisms encrusted on some of the coastal boulders. The combination of the results obtained both by the hydrodynamic equations, which provided values comparable with those observed and measured during the storms, and radiocarbon dating suggests that the majority of the boulders have been detached and moved by intense storm waves. These boulders testify to the existence of a real hazard for the coasts of Malta, i.e. that of very high storm waves, which, during exceptional storms, are able to detach large blocks of volumes exceeding 10 m3 from the coastal edge and the nearshore bottom, and also to transport them inland. Nevertheless, the occurrence of one or more tsunami events cannot be ruled out, since radiocarbon dating of some marine organisms did reveal ages which may be related to historically known tsunamis in the Mediterranean region, such as the ones in AD 963, 1329, 1693 and 1743.

scholarly journals Statistics of Simulated Storm Waves over Bathymetry

2021 ◽  
Vol 9 (7) ◽  
pp. 784
Author(s):  
Arnida Lailatul Latifah ◽  
Durra Handri ◽  
Ayu Shabrina ◽  
Henokh Hariyanto ◽  
E. van Groesen
Keyword(s):  
Water Waves ◽  
Open Water ◽  
Storm Events ◽  
Extreme Waves ◽  
Marine Structures ◽  
Wave Statistics ◽  
Storm Waves ◽  
Different Types ◽  
Run Up ◽  
Good Agreement

This paper shows simulations of high waves over different bathymetries to collect statistical information, particularly kurtosis and crest exceedance, that quantifies the occurrence of exceptionally extreme waves. This knowledge is especially pertinent for the design and operation of marine structures, safe ship trafficking, and mooring strategies for ships near the coast. Taking advantage of the flexibility to perform numerical simulations with HAWASSI software, with the aim of investigating the physical and statistical properties for these cases, this paper investigates the change in wave statistics related to changes in depth, breaking and differences between long- and short-crested waves. Three different types of bathymetry are considered: run-up to the coast with slope 1/20, waves over a shoal, and deep open-water waves. Simulations show good agreement in the examined cases compared with the available experimental data and simulations. Then predictive simulations for cases with a higher significant wave height illustrate the changes that may occur during storm events.

scholarly journals Evaluation of extreme wave probability on the basis of long-term data analysis

Ocean Science ◽  
2018 ◽  
Vol 14 (5) ◽  
pp. 1321-1327 ◽  
Author(s):  
Kirill Bulgakov ◽  
Vadim Kuzmin ◽  
Dmitry Shilov
Keyword(s):  
Wave Height ◽  
Wind Wave ◽  
Cumulative Probability ◽  
Extreme Waves ◽  
Model Data ◽  
Extreme Wave ◽  
Method Of Calculation ◽  
Wave Heights ◽  
Term Data

Abstract. A method of calculation of wind wave height probability based on the significant wave height probability is described (Chalikov and Bulgakov, 2017). The method can also be used for estimation of the height of extreme waves of any given cumulative probability. The application of the method on the basis of long-term model data is presented. Examples of averaged annual and seasonal fields of extreme wave heights obtained using the above method are given. Areas where extreme waves can appear are shown.

scholarly journals INCORPORATION OF WEIBULL DISTRIBUTION IN L-MOMENTS METHOD FOR

2011 ◽  
Vol 1 (32) ◽  
pp. 62 ◽  
Author(s):  
Yoshimi Goda ◽  
Masanobu Kudaka ◽  
Hiroyasu Kawai
Keyword(s):  
Weibull Distribution ◽  
Frequency Analysis ◽  
Coastal Engineering ◽  
Regional Frequency Analysis ◽  
Eastern Coast ◽  
Ocean Engineering ◽  
Extreme Wave ◽  
Wave Heights ◽  
L Moments ◽  
Regional Frequency

The L-moments of the Weibull distribution are derived and incorporated in the regional frequency analysis of peaksover-threshold significant wave heights at eleven stations along the eastern coast of Japan Sea. The effective duration of wave measurements varies from 18.0 to 37.2 years with the mean rate of 10.4 to 15.1 events per year. The eleven stations are divided into three regions to assure homogeneity of the data. Both the Weibull and Generalized Pareto (GPA) distributions fit well to the observed data. The 100-year wave height varied from 8.2 to 11.2 m by the Weibull and 7.6 to 10.3 m by the GPA. The GPA distribution is not recommended for determination of design waves for these stations because it has an inherent upper limit and a tendency of under-prediction. References Coles, S. 2001. An Introduction to Statistical Modeling of Extreme Values, Springer, 208p. Goda, Y., Konagaya, O., Takeshita, N., Hitomi, H., and T. Nagai. 2000. Population distribution of extreme wave heights estimated through regional analysis, Coastal Engineering 2000 (Proc. 26th ICCE, Sydney), ASCE, Sydney, 1078-1091. Greenwood, J A., J. M. Landwehr, N. C. Matalas, and J. R. Wallis. 1978. Probability weighted moments: Definition and relation to parameters of several distributions expressable in inverse form, Water Resources Res., Vol. 15, No. 5, pp. 1049-1064. http://dx.doi.org/10.1029/WR015i005p01049 Hosking, J. R. M. 1990. L-moments: Analysis and estimation of distributions using linear combinations of order statistics, J. Roy. Statistical Soc., Series B, 52, pp. 105-24. Hosking, J. R. M. and J. R. Wallis. 1997. Regional Frequency Analysis, Cambridge Univ. Press, 224p. http://dx.doi.org/10.1017/CBO9780511529443 Ma, Q.-S., Li, Y.-B., and J. Li .2006. Regional frequency analysis of siginicant wave heights based on L-moments, China Ocean Engineering, 20(1), pp. 85-98. Petruaskas, C. and P. M. Aagaard. 1971. Extrapolation of historical storm data for estimating design wave heights, J. Soc. Petroleum Engrg., 11, pp. 23-27. van Gelder, P. H. A. J. M. 2000. Statistical Methods for the Risk-Based Design of Civil Structures, Ph.D. thesis Delft University of Technology, 249p. van Gelder, P. H. A. J. M., J. De Ronde, N. W. Neykov, and P. Neytchev. 2000. Regional frequency analysis of extreme wave heights: trading space for time, Coastal Engineering 2000

scholarly journals The Relevance of Grated Inlets within Surface Drainage Systems in the Field of Urban Flood Resilience. A Review of Several Experimental and Numerical Simulation Approaches

2021 ◽  
Vol 13 (13) ◽  
pp. 7189
Author(s):  
Beniamino Russo ◽  
Manuel Gómez Valentín ◽  
Jackson Tellez-Álvarez
Keyword(s):  
Overland Flow ◽  
Drainage System ◽  
Critical Conditions ◽  
Hydraulic Efficiency ◽  
Storm Events ◽  
Urban Resilience ◽  
Urban Flood ◽  
Drainage Systems ◽  
Surface Drainage ◽  
Intense Storm

Urban drainage networks should be designed and operated preferably under open channel flow conditions without flux return, backwater, or overflows. In the case of extreme storm events, urban pluvial flooding is generated by the excess of surface runoff that could not be conveyed by pressurized sewer pipes, due to its limited capacity or, many times, due to the poor efficiency of surface drainage systems to collect uncontrolled overland flow. Generally, the hydraulic design of sewer systems is addressed more for underground networks, neglecting the surface drainage system, although inadequate inlet spacings and locations can cause dangerous flooding with relevant socio-economic impacts and the interruption of critical services and urban activities. Several experimental and numerical studies carried out at the Technical University of Catalonia (UPC) and other research institutions demonstrated that the hydraulic efficiency of inlets can be very low under critical conditions (e.g., high circulating overland flow on steep areas). In these cases, the hydraulic efficiency of conventional grated inlets and continuous transverse elements can be around 10–20%. Their hydraulic capacity, expressed in terms of discharge coefficients, shows the same criticism with values quite far from those that are usually used in several project practice phases. The grate clogging phenomenon and more intense storm events produced by climate change could further reduce the inlets’ performance. In this context, in order to improve the flood urban resilience of our cities, the relevance of the hydraulic behavior of surface drainage systems is clear.

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 EXTREME WAVE PRESSURES AND LOADS ON A PILE-SUPPORTED WHARF DECK - INFLUENCES OF AIR GAP AND WAVE DIRECTION

2018 ◽  
pp. 5
Author(s):  
Andrew Cornett
Keyword(s):  
Offshore Structures ◽  
Model Tests ◽  
Scale Model ◽  
Extreme Waves ◽  
Wave Direction ◽  
Coastal Structures ◽  
Extreme Wave ◽  
Wave Impact ◽  
The Past ◽  
Water Depths

Many deck-on-pile structures are located in shallow water depths at elevations low enough to be inundated by large waves during intense storms or tsunami. Many researchers have studied wave-in-deck loads over the past decade using a variety of theoretical, experimental, and numerical methods. Wave-in-deck loads on various pile supported coastal structures such as jetties, piers, wharves and bridges have been studied by Tirindelli et al. (2003), Cuomo et al. (2007, 2009), Murali et al. (2009), and Meng et al. (2010). All these authors analyzed data from scale model tests to investigate the pressures and loads on beam and deck elements subject to wave impact under various conditions. Wavein- deck loads on fixed offshore structures have been studied by Murray et al. (1997), Finnigan et al. (1997), Bea et al. (1999, 2001), Baarholm et al. (2004, 2009), and Raaij et al. (2007). These authors have studied both simplified and realistic deck structures using a mixture of theoretical analysis and model tests. Other researchers, including Kendon et al. (2010), Schellin et al. (2009), Lande et al. (2011) and Wemmenhove et al. (2011) have demonstrated that various CFD methods can be used to simulate the interaction of extreme waves with both simple and more realistic deck structures, and predict wave-in-deck pressures and loads.

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 The Origin of Sand and Its Colour on the South-Eastern Coast of Spain: Implications for Erosion Management

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 377 ◽  
Author(s):  
Asensio-Montesinos ◽  
Pranzini ◽  
Martínez-Martínez ◽  
Cinelli ◽  
Anfuso ◽  
...  
Keyword(s):  
Western Mediterranean ◽  
Mediterranean Coast ◽  
Eastern Coast ◽  
Storm Events ◽  
Colour Space ◽  
Source Areas ◽  
Beach Width ◽  
Severe Erosion ◽  
Colour Coordinates ◽  
Economic Function

Sand colour can give important information about mineral composition and, consequently, sediment source areas and input systems. Beach appearance, which is mostly linked to sand colour, has a relevant economic function in tourist areas. In this paper, the colour of 66 sand samples, collected along both natural and nourished beaches in the western Mediterranean coast of Spain, were assessed in CIEL*a*b* 1976 colour space. The obtained results showed relevant differences between natural and artificially nourished beaches. The colour of many nourished beaches generally differs from the native one because the origin of the injected sand is different. The native sand colour coordinates’ range is: L* (40.16–63.71); a* (−1.47–6.40); b* (7.48–18.06). On the contrary, for nourished beaches’ the colour range is: L* (47.66–70.75); a*(0.72‒5.16); b* (5.82–18.82). Impacts of beach nourishment on the native sand colour were studied at San Juan beach, the most popular one along the study area. Nourishment works were performed after severe erosion, usually linked to anthropic activities/structures and storm events, but also to increase beach width and hence benefit tourism.

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