On the effect of the sampling frequency of sea level measurements on return period estimate of extremes—Southern European examples

2009 ◽  
Vol 29 (18) ◽  
pp. 2214-2221 ◽  
Author(s):  
M.N. Tsimplis ◽  
M. Marcos ◽  
B. Pérez ◽  
P. Challenor ◽  
M.J. Garcia-Fernandez ◽  
...  
Keyword(s):  
Sea Level ◽  
Return Period ◽  
Sampling Frequency ◽  
Period Estimate

scholarly journals A century of sea level data and the UK's 2013/14 storm surges: an assessment of extremes and clustering using the Newlyn tide gauge record

2014 ◽  
Vol 11 (4) ◽  
pp. 1995-2028 ◽  
Author(s):  
M. P. Wadey ◽  
I. D. Haigh ◽  
J. M. Brown
Keyword(s):  
Sea Level ◽  
Return Period ◽  
Tide Gauge ◽  
Storm Surges ◽  
High Water ◽  
Lower Probability ◽  
Tide Gauge Record ◽  
Storm Activity ◽  
Sea Levels ◽  
Level Data

Abstract. For the UK's longest and most complete sea level record (Newlyn), we assess extreme high water events and their temporal clustering; prompted by the 2013/2014 winter of flooding and storms. These are set into context against this almost 100 yr record. We define annual periods for which storm activity, tides and sea levels can be compared on a year-by-year basis. Amongst the storms and high tides which affected Newlyn the recent winter produced the largest recorded high water (3 February 2014) and five others above a 1 in 1 yr return period. The large magnitude of tide and mean sea level, and the close inter-event spacings (of large return period high waters), suggests that the 2013/2014 high water "season" may be considered the most extreme on record. However, storm and sea level events may be classified in different ways. For example in the context of sea level rise (which we calculate linearly as 1.81 ± 0.1 mm yr−1 from 1915 to 2014), a lower probability combination of surge and tide occurred on 29 January 1948, whilst 1995/1996 storm surge season saw the most high waters of ≥ 1 in 1 yr return period. We provide a basic categorisation of five types of high water cluster, ranging from consecutive tidal cycles to multiple years. The assessment is extended to other UK sites (with shorter sea level records and different tide-surge characteristics), which suggests 2013/2014 was extreme, although further work should assess clustering mechanisms and flood system "memory".

scholarly journals Extreme Storm Surge estimation and projection through the Metastatistical Extreme Value Distribution

2021 ◽  
Author(s):  
Maria Francesca Caruso ◽  
Marco Marani
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Return Period ◽  
Extreme Value Distribution ◽  
Storm Surges ◽  
Extreme Value ◽  
Value Distribution ◽  
Sample Sizes ◽  
Sea Levels ◽  
Calibration Sample

Abstract. Accurate estimates of the probability of extreme sea levels are pivotal for assessing risk and the design of coastal defense structures. This probability is typically estimated by modelling observed sea-level records using one of a few statistical approaches. In this study we comparatively apply the Generalized Extreme Value (GEV) distribution, based on Block Maxima (BM) and Peak-Over-Threshold (POT) formulations, and the recently Metastatistical Extreme Value Distribution (MEVD) to four long time series of sea-level observations distributed along European coastlines. A cross-validation approach, dividing available data in separate calibration and test sub-samples, is used to compare their performances in high-quantile estimation. To address the limitations posed by the length of the observational time series, we quantify the estimation uncertainty associated with different calibration sample sizes, from 5 to 30 years. Focusing on events with a high return period, we find that the GEV-based approaches and MEVD perform similarly when considering short samples (5 years), while the MEVD estimates outperform the traditional methods when longer calibration sample sizes (10-30 years) are considered. We then investigate the influence of sea-level rise through 2100 on storm surges frequencies. The projections indicate an increase in the height of storm surges for a fixed return period that are spatially heterogeneous across the coastal locations explored.

scholarly journals Four Global Catastrophic Risks – A Personal View

2021 ◽  
Vol 9 ◽  
Author(s):  
Russell Blong
Keyword(s):  
Sea Level ◽  
Natural Hazards ◽  
Return Period ◽  
Extreme Events ◽  
Social Economic ◽  
Economic Losses ◽  
Personal View ◽  
Average Return ◽  
Catastrophic Risks ◽  
Near Future

Global catastrophic risks (GCRs) affect a larger than hemispheric area and produce death tolls of many millions and/or economic losses greater than several trillion USD. Here I explore the biophysical, social-economic, demographic and cultural strands of four global catastrophic risks – sea level rise, a VEI 7 eruption, a pandemic, and a geomagnetic storm – one human-exacerbated at the least, one geological, one biological in large part, and one from space. Durations of these biophysical events range from a day or two to more than 100 years and the hazards associated range from none to numerous. Each of the risks has an average return period of no more than a few hundred years and lie within a range where many regulators ordinarily demand efforts in the case of less extreme events at enhancing resilience. Losses produced by GCRs and other natural hazards are usually assessed in terms of human mortality or dollars but many less tangible losses are at least as significant. Despite the varying durations, biophysical characteristics, and the wide array of potential consequences, the aftermath at global (and at more granular scales) can be summarised by one of four potential futures. While this assessment considers the present and the near future (the Anthropocene), much of this appraisal applies also to global catastrophic risks in the Early Holocene.

Extreme Coastal Inundation Under Different Climate Scenarios: Fourchon Junction Case Study

2021 ◽  
Author(s):  
Octavio Sequeiros ◽  
Sergio Jaramillo
Keyword(s):  
Boundary Conditions ◽  
Sea Level Rise ◽  
Sea Level ◽  
Return Period ◽  
Wave Crest ◽  
Design Parameters ◽  
Extreme Value Analysis ◽  
Future Scenarios ◽  
Barrier Beach ◽  
Value Analysis

Abstract Port Fourchon Junction is located within Chevron's Fourchon Terminal, just south of Port Fourchon and is operated by Shell Pipeline Company LP. This manifold metering station is a critical junction for the Mars Corridor oil, as oil production from Mars (MC-807), Ursa (MC-809), Titan (MC-941), Who Dat (MC-547), Medusa (MC-582), and Olympus (MC-807B) flows through this station via a 24" pipeline. Port Fourchon is at the edge of the Mississippi delta facing the sea, one of the world's most vulnerable low-elevation coastal zones. It is highly exposed to storm surge and wave-induced inundation under hurricanes which regularly visit the Gulf of Mexico. In addition, it experiences one of the largest rates of subsidence in the world, which combined with sea level rise, will increase the site vulnerability in the coming decades. This study assesses present and future scenarios of subsidence and sea level rise under extreme metocean conditions induced by hurricanes and their impact on Port Fourchon Junction. Local effects such as the differential settlement of the barrier beach have been also considered. Using results from the numerical model XBeach, a set of different present and future scenarios are modelled under extreme metocean conditions. These conditions and the subsequent design parameters calculated, are not obtained through traditional extreme value analysis methods, instead, they are estimated through the influence of boundary conditions forced with the corresponding return period values of the parameters. Boundary conditions for the simulations are extracted from Grand Isle and Port Fourchon sea level observations, and from FEMA and the Water Institute of the Gulf simulations. Port Fourchon site should be subject to flooding for 10-year return period conditions based on Grand Isle observations. For 5-6 years return period conditions some degree of milder partial flood should also be expected. This is well captured by the model. While the highest inundating level is mostly dependent on winds, waves and surge acting together, surge is the single most critical parameter that defines the asset's base inundation level. Design future conditions based on surge extreme from FEMA simulations are recommended over surge extremes derived from Grand Isle observations. The barrier beach and the breakwaters play a key factor in sheltering site from waves and surge. Even when submerged under extreme high return period conditions they dissipate the waves ensuring that the maximum water level (wave crest elevation) on site is lower than would otherwise be without them. It is then important to maintain them fit for purpose during the entire lifespan of the asset. Both Grand Isle and Port Fourchon subsidence scenarios yield similar results. Based on the importance of Port Fourchon Junction facilities, the design criteria obtained, and the higher subsidence level observed at Port Fourchon (compared to Grand Isle), it is recommended that a 1000-year return period and future scenario based on FEMA surge level and Port Fourchon Relative Sea Level Rise (RSLR) is adopted for design. The subsidence associated to this scenario is 9.8 mm/year. The sea level rise associated to this scenario is 2 mm/year.

scholarly journals A century of sea level data and the UK's 2013/14 storm surges: an assessment of extremes and clustering using the Newlyn tide gauge record

Ocean Science ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 1031-1045 ◽  
Author(s):  
M. P. Wadey ◽  
I. D. Haigh ◽  
J. M. Brown
Keyword(s):  
Water Level ◽  
Sea Level ◽  
Return Period ◽  
Tide Gauge ◽  
Storm Surges ◽  
High Water ◽  
Lower Probability ◽  
Tide Gauge Record ◽  
Storm Activity ◽  
High Water Level

Abstract. For the UK's longest and most complete sea level record (Newlyn), we assess extreme high waters and their temporal clustering; prompted by the 2013/2014 winter of storms and flooding. These are set into context against this almost 100-year record. We define annual periods for which storm activity and high sea levels can be compared on a year-by-year basis. Amongst the storms and high tides which affected Newlyn, the recent winter produced the largest recorded high water level (3 February 2014) and five other high water events above a 1 in 1-year return period. The large magnitude of tide and mean sea level, and the close inter-event spacings (of large return period high waters), suggests that the 2013/2014 extreme high water level "season" can be considered the most extreme on record. However, storm and sea level events may be classified in different ways. For example, in the context of sea level rise (which we calculate linearly as 1.81 ± 0.1 mm yr−1 from records between 1915 to 2014), a lower probability combination of surge and tide occurred on 29 January 1948, whilst the 1995/1996 storm surge season saw the most high waters of ≥ the 1 in 1-year return period. We provide a basic categorisation of the four types of extreme high water level cluster, ranging from consecutive tidal cycles to multiple years. The assessment is extended to other UK sites (with shorter sea level records and different tide-surge characteristics), which suggests 2013/2014 was particularly unusual. Further work will assess clustering mechanisms and flood system "memory".

scholarly journals Hurricane Sandy’s flood frequency increasing from year 1800 to 2100

2016 ◽  
Vol 113 (43) ◽  
pp. 12071-12075 ◽  
Author(s):  
Ning Lin ◽  
Robert E. Kopp ◽  
Benjamin P. Horton ◽  
Jeffrey P. Donnelly
Keyword(s):  
New York ◽  
Sea Level ◽  
Storm Surge ◽  
21St Century ◽  
Return Period ◽  
Temporal Evolution ◽  
Flood Hazard ◽  
Flood Frequency ◽  
The Past ◽  
Probabilistic Projections

Coastal flood hazard varies in response to changes in storm surge climatology and the sea level. Here we combine probabilistic projections of the sea level and storm surge climatology to estimate the temporal evolution of flood hazard. We find that New York City’s flood hazard has increased significantly over the past two centuries and is very likely to increase more sharply over the 21st century. Due to the effect of sea level rise, the return period of Hurricane Sandy’s flood height decreased by a factor of ∼3× from year 1800 to 2000 and is estimated to decrease by a further ∼4.4× from 2000 to 2100 under a moderate-emissions pathway. When potential storm climatology change over the 21st century is also accounted for, Sandy’s return period is estimated to decrease by ∼3× to 17× from 2000 to 2100.

scholarly journals Assessment and comparison of extreme sea levels and waves during the 2013/2014 storm season in two UK coastal regions

2015 ◽  
Vol 3 (4) ◽  
pp. 2665-2708 ◽  
Author(s):  
M. P. Wadey ◽  
J. M. Brown ◽  
I. D. Haigh ◽  
T. Dolphin ◽  
P. Wisse
Keyword(s):  
Sea Level ◽  
Return Period ◽  
Data Sets ◽  
Return Periods ◽  
National Scale ◽  
Sea Levels ◽  
Extreme Sea Levels ◽  
Study Sites

Abstract. The extreme sea levels and waves experienced around the UK's coast during the 2013/2014 winter caused extensive coastal flooding and damage. In such circumstances, coastal managers seek to place such extremes in relation to the anticipated standards of flood protection, and the long-term recovery of the natural system. In this context, return periods are often used as a form of guidance. We therefore provide these levels for the winter storms, as well as discussing their application to the given data sets and case studies (two UK case study sites: Sefton, northwest England; and Suffolk, east England). We use tide gauge records and wave buoy data to compare the 2013/2014 storms with return periods from a national dataset, and also generate joint probabilities of sea level and waves, incorporating the recent events. The UK was hit at a national scale by the 2013/2014 storms, although the return periods differ with location. We also note that the 2013/2014 high water and waves were extreme due to the number of events, as well as the extremity of the 5 December 2013 "Xaver" storm, which had a very high return period at both case study sites. Our return period analysis shows that the national scale impact of this event is due to its coincidence with spring high tide at multiple locations as the tide and storm propagated across the continental shelf. Given that this event is such an outlier in the joint probability analyses of these observed data sets, and that the season saw several events in close succession, coastal defences appear to have provided a good level of protection. This type of assessment should be recorded alongside details of defence performance and upgrade, with other variables (e.g. river levels at estuarine locations) included and appropriate offsetting for linear trends (e.g. mean sea level rise) so that the storm-driven component of coastal flood events can be determined. Local offsetting of the mean trends in sea level allows long-term comparison of storm severity and also enables an assessment of how sea level rise is influencing return levels over time, which is important when considering long-term coastal resilience in strategic management plans.

scholarly journals Hydro- and Morphodynamic Impacts of Sea Level Rise: The Minho Estuary Case Study

2020 ◽  
Vol 8 (6) ◽  
pp. 441
Author(s):  
Willian Melo ◽  
José Pinho ◽  
Isabel Iglesias ◽  
Ana Bio ◽  
Paulo Avilez-Valente ◽  
...  
Keyword(s):  
Climate Change ◽  
Sediment Transport ◽  
Numerical Modelling ◽  
Sea Level Rise ◽  
Sea Level ◽  
Return Period ◽  
Methodological Approach ◽  
River Mouth ◽  
Rcp 8.5 ◽  
Minho Estuary

The understanding and anticipating of climate change impacts is one of the greatest challenges for humanity. It is already known that, until the end of the 21st century, the mean sea level (MSL) will rise at a global scale, but its effects at the local scale need to be further analyzed. In this context, a numerical modelling tool and a methodological approach for the river Minho estuary (NW of the Iberian Peninsula) are presented, to predict possible consequences of local MSL rise, considering the greenhouse emission scenarios RCP 4.5 and RCP 8.5. Hydrodynamic and morphodynamic impacts were analyzed considering several driving factors, such as tides, sea level rise, storm surge, wave set-up, and different river flood peak discharges, taking into account their probabilities of occurrence. The model was calibrated using in-situ data and a data assimilation tool, the OpenDA, which automates this process, allowing to reach reliable results in a considerably short time when compared with traditional techniques. The results forecast that the predicted MSL rise will reduce the flow velocity magnitude and the sediment transport into the coastal platform but will aggravate the inundation risks along the estuarine banks. In the worst scenario (RCP 8.5) the water level near the river mouth of the estuary is expected to rise 0.20 m for 50 years return period ocean water rising, and 0.60 m for 100 years return period. It was also possible to identify that floods are the most important driver for the sediment transport along the estuary, while the tide effect in the morphodynamics is restricted to the downstream estuarine region. This work demonstrated the importance of the numerical modelling tools to better understand the effects of climate change at local scales through the representation of the estuarine hydrodynamic pattern evolution for future climate scenarios.

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