Extended water level trends at long‐record tide gauges via moving window averaging and implications for future coastal flooding

2021 ◽  
Author(s):  
Adam T. Devlin ◽  
Jiayi Pan ◽  
Hui Lin
Keyword(s):  
Water Level ◽  
Coastal Flooding ◽  
Moving Window ◽  
Tide Gauges

scholarly journals The Role of Mean Sea Level Annual Cycle on Extreme Water Levels Along European Coastline

2020 ◽  
Vol 12 (20) ◽  
pp. 3419
Author(s):  
Tomás Fernández-Montblanc ◽  
Jesús Gómez-Enri ◽  
Paolo Ciavola
Keyword(s):  
Water Level ◽  
Sea Level ◽  
North Sea ◽  
Extreme Events ◽  
Annual Cycle ◽  
Coastal Flooding ◽  
Water Levels ◽  
Total Water ◽  
Mean Sea Level ◽  
The Impact

The knowledge of extreme total water levels (ETWLs) and the derived impact, coastal flooding and erosion, is crucial to face the present and future challenges exacerbated in European densely populated coastal areas. Based on 24 years (1993–2016) of multimission radar altimetry, this paper investigates the contribution of each water level component: tide, surge and annual cycle of monthly mean sea level (MMSL) to the ETWLs. It focuses on the contribution of the annual variation of MMSL in the coastal flooding extreme events registered in a European database. In microtidal areas (Black, Baltic and Mediterranean Sea), the MMSL contribution is mostly larger than tide, and it can be at the same order of magnitude of the surge. In meso and macrotidal areas, the MMSL contribution is <20% of the total water level, but larger (>30%) in the North Sea. No correlation was observed between the average annual cycle of monthly mean sea level (AMMSL) and coastal flooding extreme events (CFEEs) along the European coastal line. Positive correlations of the component variance of MMSL with the relative frequency of CFEEs extend to the Central Mediterranean (r = 0.59), North Sea (r = 0.60) and Baltic Sea (r = 0.75). In the case of positive MMSL anomalies, the correlation expands to the Bay of Biscay and northern North Atlantic (at >90% of statistical significance). The understanding of the spatial and temporal patterns of a combination of all the components of the ETWLs shall improve the preparedness and coastal adaptation measures to reduce the impact of coastal flooding.

Uncertainty in coastal flooding: modelling and visualisation

2020 ◽  
Author(s):  
John Maskell
Keyword(s):  
Water Level ◽  
Storm Surge ◽  
Return Period ◽  
Flood Risk ◽  
High Water ◽  
Coastal Flooding ◽  
Water Levels ◽  
Tidal Range ◽  
The Uk ◽  
Flood Maps

&lt;p&gt;Two case studies are considered in the UK, where uncertainty and drivers of coastal flood risk are explored through modelling and visualisations. Visualising the impact of uncertainty is a useful way of explaining the potential range of predicted or simulated flood risk to both expert and non-expert stakeholders.&lt;/p&gt;&lt;p&gt;Significant flooding occurred in December 2013 and January 2017 at Hornsea on the UK East Coast, where storm surge levels and waves overtopped the town&amp;#8217;s coastal defences. Uncertainty in the potential coastal flooding is visualised at Hornsea due to the range of uncertainty in the 100-year return period water level and in the calculated overtopping due to 3 m waves at the defences. The range of uncertainty in the simulated flooding is visualised through flood maps, where various combinations of the uncertainties decrease or increase the simulated inundated area by 58% and 82% respectively.&lt;/p&gt;&lt;p&gt;Located at the mouth of the Mersey Estuary and facing the Irish Sea, New Brighton is affected by a large tidal range with potential storm surge and large waves. Uncertainty in the coastal flooding at the 100-year return period due to the combination of water levels and waves is explored through Monte-Carlo analysis and hydrodynamic modelling. Visualisation through flood maps shows that the inundation extent at New Brighton varies significantly for combined wave and surge events with a joint probability of 100 years, where the total flooded area ranges from 0 m&lt;sup&gt;2&lt;/sup&gt; to 10,300 m&lt;sup&gt;2&lt;/sup&gt;. Waves are an important flood mechanism at New Brighton but are dependent on high water levels to impact the coastal defences and reduce the effective freeboard. The combination of waves and high-water levels at this return level not only determine the magnitude of the flood extent but also the spatial characteristics of the risk, whereby flooding of residential properties is dominated by overflow from high water levels, and commercial and leisure properties are affected by large waves that occur when the water level is relatively high at the defences.&lt;/p&gt;

Application of the Spectral Nudging on Global Tides Towards a Global Total Water Level Prediction System

2019 ◽  
Author(s):  
Tsubasa Kodaira ◽  
Natacha Bernier ◽  
Keith R. Thompson
Keyword(s):  
Water Level ◽  
Coastal Flooding ◽  
Ocean Model ◽  
Global Ocean ◽  
Total Water ◽  
Spectral Leakage ◽  
Spectral Nudging ◽  
Vector Difference ◽  
Tidal Constituents ◽  
Total Water Level

Abstract With the long-term goal of developing an ensemble forecast system for coastal flooding, we are developing a dynamically-based, numerical model of the global ocean. The model is based on the NEMO framework and has been used to predict global tides and surges in previous studies. This study focuses on the optimization of the joint prediction of both tides and surges, the two main components of total water level that cause coastal flooding. To improve the predictions of the tide we use a modified form of “spectral nudging”. We show this leads to significant improvements in the prediction of the M2 tide in the open ocean, and also in the shallow regions closer to shore where the model is not nudged. The median value of the vector difference of the tidal amplitude based on sea level observations and a data-assimilative model, and the predictions of our ocean model, is reduced from 11.2 cm to 2.66 cm by the nudging. The improvement deteriorates significantly however if additional tidal constituents are included in the model (most notably S2). This is explained in terms of spectral leakage between tidal bands associated with the nudging methodology and a straightforward solution is proposed.

scholarly journals Pembangunan Sistem Pengukuran Muka Air Otomatis (Automatic Water Level Recorder) Berbasis Gelombang Akustik Untuk Pengamatan Pasang Surut Laut

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Agung Pandi Nugroho ◽  
Nirmawana Simarmata ◽  
Irdam Adil
Keyword(s):  
Open Source ◽  
Water Level ◽  
Acoustic Waves ◽  
Lower Cost ◽  
Water Levels ◽  
Tide Gauges ◽  
Field Scale ◽  
Hardware System ◽  
Level Recorder ◽  
Water Level Recorder

AbstrakPasang surut adalah fenomena naik turunnya muka air. Pasut dapat diukur dengan berbagai macam metode, baik manual maupu otomatis. Pengukuran otomatis dengan menggunakan alat pengukur pasut, khususnya untuk pengukuran jangka panjang dinilai relatif lebih berbiaya rendah dibandingkan dengan pengukuran manual, akan tetapi alat pengukur pasut otomatis hampir semuanya memiliki harga yang relatif mahal sehingga diperlukan peralatan yang lebih terjangkau dan andal. Pengembangan sistem automatic water level recorder (AWLR) berbasis gelombang akustik dilakukan dengan membangun dan merancang sistem perangkat lunak maupun perangkat keras alat dengan berbasiskan perangkat open source Arduino. Alat yang dihasilkan dapat mengukur dengan baik di skala laboratorium maupun lapangan. Pengukuran skala lapangan menunjukkan RMSE 36,6 cm di daerah terpencil dan RMSE 11 cm untuk daerah yang memungkinkan alat dipasang dengan stabil.Kata Kunci : AWLR, pengukur pasut otomatis, skala lapangan, skala laboratorium.AbstractTides were phenomenon of  rising water levels. Tides could be measured by various methods, manual or automatic way. Measurements using automatic tide gauges, especially for long-term measurements, usually needed lower cost compared to manual ones, but in facts automatic tide gauges were relatively more expensive prices, so it was worthy to develop the reliable equipment with lower cost. This automatic water level recorder (AWLR) system using acoustic waves was developed by building and designing a software and hardware system based on an open source device named Arduino. The builded equipment had could reached well level in scales, laboratory or field scales. Field scale measurements showed that RMSE in outlying areas reached 36.6 centimeters and could be better for areas where tide gauges could be installed stably (11 centimeters).Keywords: AWLR, automatic tide gauges, field scale, laboratory scale

scholarly journals Evaluating essential processes and forecast requirements for meteotsunami-induced coastal flooding

2021 ◽  
Author(s):  
Chenfu Huang ◽  
Eric Anderson ◽  
Yi Liu ◽  
Gangfeng Ma ◽  
Greg Mann ◽  
...  
Keyword(s):  
Great Lakes ◽  
Water Level ◽  
Wind Wave ◽  
System Development ◽  
Hot Spot ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Coastal Flooding ◽  
Grid Resolution ◽  
Hydrodynamic Processes

AbstractMeteotsunamis pose a unique threat to coastal communities and often lead to damage of coastal infrastructure, deluge of nearby property, and loss of life and injury. The Great Lakes are a known hot-spot of meteotsunami activity and serve as an important region for investigation of essential hydrodynamic processes and model forecast requirements in meteotsunami-induced coastal flooding. For this work, we developed an advanced hydrodynamic model and evaluate key model attributes and dynamic processes, including: (1) coastal model grid resolution and wetting and drying process in low-lying zones, (2) coastal infrastructure, including breakwaters and associated submerging and overtopping processes, (3) annual/seasonal (ambient) water level change, and (4) wind wave-current coupling. Numerical experiments are designed to evaluate the importance of these attributes to meteotsunami modeling, including a “representative storm” scenario in the context of regional climate change in which a meteotsunami wave is generated under high ambient lake-level conditions with a preferable wind direction and speed for wind-wave growth. Results demonstrate that accurate representation of coastal topography and fully resolving associated hydrodynamic processes are critical to forecasting the realistic hazards associated with meteotsunami events. As most of existing coastal forecast systems generally do not resolve many of these features due to insufficient model grid resolution or lack of essential model attributes, this work shows that calibrating or assessing existing forecast models against coastal water level gauges alone may result in underestimating the meteotsunami hazard, particularly when gauging stations are sparse and located behind harbor breakwaters or inside estuaries, which represent dampened or otherwise unrepresentative pictures of meteotsunami intensity. This work is the first hydrodynamic modeling of meteotsunami-induced coastal flooding for the Great Lakes, and serves as a template to guide where resources may be most beneficial in forecast system development and implementation.

scholarly journals Long-Term, Seasonal and Short-Term Fluctuations in the Water Level of the Southern Baltic Sea

2014 ◽  
Vol 33 (3) ◽  
pp. 181-197 ◽  
Author(s):  
Tomasz Wolski ◽  
Bernard Wiśniewski
Keyword(s):  
Baltic Sea ◽  
Water Level ◽  
Sea Level ◽  
Tide Gauges ◽  
Short Term ◽  
Sea Levels ◽  
Extreme Sea Levels ◽  
Solar Tide ◽  
Southern Baltic

Abstract Aim of this work are analyses of oscillations sea levels in the Southern Baltic on a scale of short-term changes, seasonal and long-term (age). The study was based on observational data in different periods time for tide gauges station of the Polish coast. On the example of some storm situations presents the part of the baric wave and the wind in the formation of extreme sea levels. The primary cause of the annual variability of sea levels was the characteristics of the annual and semi-annual oscillations (the annual and semi-annual solar tide). In the work also determined the rate of long-term sea-level rise for the Polish coast.

scholarly journals Developments in large-scale coastal flood hazard mapping

2016 ◽  
Vol 16 (8) ◽  
pp. 1841-1853 ◽  
Author(s):  
Michalis I. Vousdoukas ◽  
Evangelos Voukouvalas ◽  
Lorenzo Mentaschi ◽  
Francesco Dottori ◽  
Alessio Giardino ◽  
...  
Keyword(s):  
Water Level ◽  
Large Scale ◽  
Flood Hazard ◽  
Coastal Flooding ◽  
Hazard Mapping ◽  
Volume Discharge ◽  
Total Water ◽  
Computational Costs ◽  
Coastal Flood ◽  
Total Water Level

Abstract. Coastal flooding related to marine extreme events has severe socioeconomic impacts, and even though the latter are projected to increase under the changing climate, there is a clear deficit of information and predictive capacity related to coastal flood mapping. The present contribution reports on efforts towards a new methodology for mapping coastal flood hazard at European scale, combining (i) the contribution of waves to the total water level; (ii) improved inundation modeling; and (iii) an open, physics-based framework which can be constantly upgraded, whenever new and more accurate data become available. Four inundation approaches of gradually increasing complexity and computational costs were evaluated in terms of their applicability to large-scale coastal flooding mapping: static inundation (SM); a semi-dynamic method, considering the water volume discharge over the dykes (VD); the flood intensity index approach (Iw); and the model LISFLOOD-FP (LFP). A validation test performed against observed flood extents during the Xynthia storm event showed that SM and VD can lead to an overestimation of flood extents by 232 and 209 %, while Iw and LFP showed satisfactory predictive skill. Application at pan-European scale for the present-day 100-year event confirmed that static approaches can overestimate flood extents by 56 % compared to LFP; however, Iw can deliver results of reasonable accuracy in cases when reduced computational costs are a priority. Moreover, omitting the wave contribution in the extreme total water level (TWL) can result in a  ∼  60 % underestimation of the flooded area. The present findings have implications for impact assessment studies, since combination of the estimated inundation maps with population exposure maps revealed differences in the estimated number of people affected within the 20–70 % range.

scholarly journals The role of tidal modulation in coastal flooding on a micro-tidal coast during Central American Cold Surge events

2017 ◽  
Author(s):  
Wilmer Rey ◽  
Paulo Salles ◽  
E. Tonatiuh Mendoza ◽  
Alec Torres-Freyermuth ◽  
Christian M. Appendini
Keyword(s):  
Water Level ◽  
Sea Level ◽  
High Tide ◽  
Coastal Flooding ◽  
Numerical Results ◽  
Water Levels ◽  
Flood Hazards ◽  
Wave Setup ◽  
Set Up

Abstract. Coastal flooding in the Yucatan Peninsula is mainly associated with storm surge events triggered by high-pressure cold fronts systems passing through the Gulf of Mexico. To assess coastal flood hazards, this study uses a thirty-year water level hindcast, and considers the contribution of wave setup and the role of tidal hydrodynamics. To diagnose the mechanisms controlling the water levels, extreme sea level occurrence probability at Progreso Port was performed to identify the two worst storms in terms of maximum residual tide (Event A), and maximum water level (Event B). Numerical results suggest that during Event A the wave setup contribution reaches 0.35 m at the coast and 0.17 m inside the back-barrier lagoon, while these values are smaller for Event B (0.30 m and 0.14 m, respectively). Besides, numerical results of the effect of the astronomical tidal phase on the wave set-up and the residual sea level show that: (i) the wave set-up is tidally modulated and contributes up to 14 % to the extreme water levels at the inlet, (ii) the residual tide is larger (smaller) during near-low (high) or receding (rising) tide, and (iii) maximum flooding occurs when the storm peak coincides with rising or high tide, despite micro-tidal conditions.

Developing impact-based thresholds for coastal inundation from tide gauge observations

2019 ◽  
Vol 69 (1) ◽  
pp. 252 ◽  
Author(s):  
Ben S. Hague ◽  
Bradley F. Murphy ◽  
David A. Jones ◽  
Andy J. Taylor
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tide Gauge ◽  
Coastal Flooding ◽  
South Coast ◽  
Tide Gauges ◽  
Coastal Inundation ◽  
Sea Levels ◽  
Coastal Flood ◽  
Flood Warnings

This study presents the first assessment of the observed frequency of the impacts of high sea levels at locations along Australia’s northern coastline. We used a new methodology to systematically define impact-based thresholds for coastal tide gauges, utilising reports of coastal inundation from diverse sources. This method permitted a holistic consideration of impact-producing relative sea-level extremes without attributing physical causes. Impact-based thresholds may also provide a basis for the development of meaningful coastal flood warnings, forecasts and monitoring in the future. These services will become increasingly important as sea-level rise continues.The frequency of high sea-level events leading to coastal flooding increased at all 21 locations where impact-based thresholds were defined. Although we did not undertake a formal attribution, this increase was consistent with the well-documented rise in global sea levels. Notably, tide gauges from the south coast of Queensland showed that frequent coastal inundation was already occurring. At Brisbane and the Sunshine Coast, impact-based thresholds were being exceeded on average 21.6 and 24.3 h per year respectively. In the case of Brisbane, the number of hours of inundation annually has increased fourfold since 1977.

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