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

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.

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Assessment of coastal flooding and associated hydrodynamic processes on the south-eastern coast of Mexico, during Central American cold surge events

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-1681-2018 ◽

2018 ◽

Vol 18 (6) ◽

pp. 1681-1701 ◽

Cited By ~ 5

Author(s):

Wilmer Rey ◽

Paulo Salles ◽

E. Tonatiuh Mendoza ◽

Alec Torres-Freyermuth ◽

Christian M. Appendini

Keyword(s):

Water Level ◽

Tide Gauge ◽

High Tide ◽

Coastal Flooding ◽

Numerical Results ◽

Eastern Coast ◽

Tide Gauge Records ◽

Relative Contribution ◽

Hydrodynamic Processes ◽

Set Up

Abstract. Coastal flooding in the northern Yucatán Peninsula is mainly associated with storm surge events triggered by high-pressure cold front systems. This study evaluates the hydrodynamic processes of the Chelem lagoon, Mexico and the flooding threat from cold fronts for the neighbouring town of Progreso. A 30-year water-level hindcast (excluding wave set-up) was performed because of the lack of long-term tide gauge records. In order to assess the relative contribution from wave set-up and residual and astronomical tides to total flooding, the two worst storm scenarios in terms of maximum residual tide (Event A) and maximum water level (Event B) were simulated. Numerical results suggest that during Event A the wave set-up contribution reaches 0.35 at the coast and 0.17 m inside the lagoon, and these values are smaller for Event B (0.30 and 0.14 m, respectively). Results of the effect of the tidal phase on wave set-up and residual sea level show that (i) the wave set-up contribution increases during ebb tide and decreases during flood tide at the Chelem inlet, (ii) the residual tide is larger (smaller) near low (high) or receding (rising) tide, and (iii) maximum flooding occurs when the storm peak coincides with rising or high tide. The numerical results confirm the important role of wave set-up on the assessment of coastal flooding in micro-tidal coastal environments.

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

Remote Sensing ◽

10.3390/rs12203419 ◽

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.

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Sustained wind forcing and water level anomalies in Annapolis, MD

Earth Interactions ◽

10.1175/ei-d-21-0013.1 ◽

2021 ◽

pp. 1-36

Keyword(s):

Sea Level Rise ◽

Water Level ◽

Sea Level ◽

Negative Impact ◽

Water Levels ◽

Wind Forcing ◽

Temporal Scales ◽

Spatial And Temporal Scales ◽

Episodic Events

Abstract Like many coastal communities throughout the Mid-Atlantic region, relative sea level rise and accelerating instances of coastal nuisance flooding are having a tangible negative impact on economic activity and infrastructure in Annapolis, MD. The drivers of coastal nuisance flooding, in general, are a superposition of global, regional, and local influences that occur across spatial and temporal scales that determine water levels relative to a coastal datum. Most of the research to date related to coastal flooding has been focused on high impact episodic events, decomposing the global and regional drivers of sea level rise, or assessing seasonal to interannual trends in. In this study, we focus specifically on the role of short-duration (hours) meteorological wind forcing on water level anomalies in Annapolis, MD. Annapolis is an ideal location to study these processes because of the orientation of the coast relative to the prevailing wind directions, and the long record of reliable data observations. Our results suggest that three-, six-, nine-, and twelve-hour sustained wind forcing significantly influences water level anomalies in Annapolis. Sustained wind forcing out of the northeast, east, southeast and south is associated with positive water level anomalies, and sustained wind forcing out of the northwest and north is associated with negative water level anomalies. While these observational results suggest a relationship between sustained wind forcing and water level anomalies, a more robust approach is needed to account for other meteorological variables and drivers that occur across a variety of spatial and temporal scales.

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Spatial distribution of water level impact to back-barrier bays

10.5194/nhess-2018-320 ◽

2018 ◽

Author(s):

Alfredo L. Aretxabaleta ◽

Neil K. Ganju ◽

Zafer Defne ◽

Richard P. Signell

Keyword(s):

Water Level ◽

Sea Level ◽

Water Levels ◽

Analytical Models ◽

Barnegat Bay ◽

Sea Level Fluctuations ◽

Flooding Hazard ◽

Short Period ◽

Inlet Geometry ◽

Spatial Estimates

Abstract. Water level in semi-enclosed bays, landward of barrier islands, is mainly driven by offshore sea level fluctuations that are modulated by bay geometry and bathymetry, causing spatial variability in the ensuing response (transfer). Local wind setup can have a secondary role that depends on wind speed, fetch, and relative orientation of the wind direction and the bay. Inlet geometry and bathymetry primarily regulate the magnitude of the transfer between open ocean and bay. Tides and short-period offshore oscillations are more damped in the bays than longer-lasting offshore fluctuations, such as storm surge and sea level rise. We compare observed and modeled water levels at stations in a mid-Atlantic bay (Barnegat Bay) with offshore water level proxies. Observed water levels in Barnegat Bay are compared and combined with model results from the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system to evaluate the spatial structure of the water level transfer. Analytical models based on the dimensional characteristics of the bay are used to combine the observed data and the numerical model results in a physically consistent approach. Model water level transfers match observed values at locations inside the Bay in the storm frequency band (transfers ranging from 70–100 %) and tidal frequencies (10–55 %). The contribution of frequency-dependent local setup caused by wind acting along the bay is also considered. The approach provides transfer estimates for locations inside the Bay where observations were not available resulting in a complete spatial characterization. The approach allows for the study of the Bay response to alternative forcing scenarios (landscape changes, future storms, and rising sea level). Detailed spatial estimates of water level transfer can inform decisions on inlet management and contribute to the assessment of current and future flooding hazard in back-barrier bays and along mainland shorelines.

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Quantifying Uncertainty in Exposure to Coastal Hazards Associated with Both Climate Change and Adaptation Strategies: A U.S. Pacific Northwest Alternative Coastal Futures Analysis

Water ◽

10.3390/w13040545 ◽

2021 ◽

Vol 13 (4) ◽

pp. 545

Author(s):

Alexis K. Mills ◽

Peter Ruggiero ◽

John P. Bolte ◽

Katherine A. Serafin ◽

Eva Lipiec

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Performance Metrics ◽

Coastal Flooding ◽

Water Levels ◽

Coastal Hazards ◽

Policy Decisions ◽

Management Decisions ◽

Quantifying Uncertainty

Coastal communities face heightened risk to coastal flooding and erosion hazards due to sea-level rise, changing storminess patterns, and evolving human development pressures. Incorporating uncertainty associated with both climate change and the range of possible adaptation measures is essential for projecting the evolving exposure to coastal flooding and erosion, as well as associated community vulnerability through time. A spatially explicit agent-based modeling platform, that provides a scenario-based framework for examining interactions between human and natural systems across a landscape, was used in Tillamook County, OR (USA) to explore strategies that may reduce exposure to coastal hazards within the context of climate change. Probabilistic simulations of extreme water levels were used to assess the impacts of variable projections of sea-level rise and storminess both as individual climate drivers and under a range of integrated climate change scenarios through the end of the century. Additionally, policy drivers, modeled both as individual management decisions and as policies integrated within adaptation scenarios, captured variability in possible human response to increased hazards risk. The relative contribution of variability and uncertainty from both climate change and policy decisions was quantified using three stakeholder relevant landscape performance metrics related to flooding, erosion, and recreational beach accessibility. In general, policy decisions introduced greater variability and uncertainty to the impacts of coastal hazards than climate change uncertainty. Quantifying uncertainty across a suite of coproduced performance metrics can help determine the relative impact of management decisions on the adaptive capacity of communities under future climate scenarios.

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Compounding effects of sea level rise and fluvial flooding

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1620325114 ◽

2017 ◽

Vol 114 (37) ◽

pp. 9785-9790 ◽

Cited By ~ 104

Author(s):

Hamed R. Moftakhari ◽

Gianfausto Salvadori ◽

Amir AghaKouchak ◽

Brett F. Sanders ◽

Richard A. Matthew

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Hazard Assessment ◽

Failure Probability ◽

River Flow ◽

Flood Hazard ◽

High Tide ◽

Probability Method ◽

Flood Hazards ◽

Flood Hazard Assessment

Sea level rise (SLR), a well-documented and urgent aspect of anthropogenic global warming, threatens population and assets located in low-lying coastal regions all around the world. Common flood hazard assessment practices typically account for one driver at a time (e.g., either fluvial flooding only or ocean flooding only), whereas coastal cities vulnerable to SLR are at risk for flooding from multiple drivers (e.g., extreme coastal high tide, storm surge, and river flow). Here, we propose a bivariate flood hazard assessment approach that accounts for compound flooding from river flow and coastal water level, and we show that a univariate approach may not appropriately characterize the flood hazard if there are compounding effects. Using copulas and bivariate dependence analysis, we also quantify the increases in failure probabilities for 2030 and 2050 caused by SLR under representative concentration pathways 4.5 and 8.5. Additionally, the increase in failure probability is shown to be strongly affected by compounding effects. The proposed failure probability method offers an innovative tool for assessing compounding flood hazards in a warming climate.

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The role of the reef–dune system in coastal protection in Puerto Morelos (Mexico)

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-1247-2018 ◽

2018 ◽

Vol 18 (4) ◽

pp. 1247-1260 ◽

Cited By ~ 4

Author(s):

Gemma L. Franklin ◽

Alec Torres-Freyermuth ◽

Gabriela Medellin ◽

María Eugenia Allende-Arandia ◽

Christian M. Appendini

Keyword(s):

Sand Dunes ◽

Coastal Flooding ◽

Water Levels ◽

Coastal Protection ◽

Dune System ◽

Fore Reef ◽

Extreme Water Levels ◽

Reef Environments ◽

Storm Impact

Abstract. Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90 % of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of barrier reefs and dunes in coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to theoretically investigate the role of the reef–dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea, using a widely validated nonlinear non-hydrostatic numerical model (SWASH). Wave hindcast information, tidal level, and a measured beach profile of the reef–dune system in Puerto Morelos are employed to estimate extreme runup and the storm impact scale for current and theoretical scenarios. The numerical results show the importance of including the storm surge when predicting extreme water levels and also show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. The latter highlights the importance of conservation of the system as a mitigation measure to decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term. Furthermore, the results are used to evaluate the applicability of runup parameterisations for beaches to reef environments. Numerical analysis of runup dynamics suggests that runup parameterisations for reef environments can be improved by including the fore reef slope. Therefore, future research to develop runup parameterisations incorporating reef geometry features (e.g. reef crest elevation, reef lagoon width, fore reef slope) is warranted.

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Determining Extreme Still Water Levels for Design and Planning Purposes Incorporating Sea Level Rise: Sydney, Australia

Atmosphere ◽

10.3390/atmos13010095 ◽

2022 ◽

Vol 13 (1) ◽

pp. 95

Author(s):

Phil J. Watson

Keyword(s):

Sea Level Rise ◽

Water Level ◽

Sea Level ◽

Tide Gauge ◽

Water Levels ◽

Extreme Value Analysis ◽

Tide Gauge Record ◽

Value Analysis ◽

Mean Sea Level ◽

The Impact

This paper provides an Extreme Value Analysis (EVA) of the hourly water level record at Fort Denison dating back to 1915 to understand the statistical likelihood of the combination of high predicted tides and the more dynamic influences that can drive ocean water levels higher at the coast. The analysis is based on the Peaks-Over-Threshold (POT) method using a fitted Generalised Pareto Distribution (GPD) function to estimate extreme hourly heights above mean sea level. The analysis highlights the impact of the 1974 East Coast Low event and rarity of the associated measured water level above mean sea level at Sydney, with an estimated return period exceeding 1000 years. Extreme hourly predictions are integrated with future projections of sea level rise to provide estimates of relevant still water levels at 2050, 2070 and 2100 for a range of return periods (1 to 1000 years) for use in coastal zone management, design, and sea level rise adaptation planning along the NSW coastline. The analytical procedures described provide a step-by-step guide for practitioners on how to develop similar baseline information from any long tide gauge record and the associated limitations and key sensitivities that must be understood and appreciated in applying EVA.

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High accuracy coastal flood mapping for Norway using LiDAR data

10.5194/nhess-2019-217 ◽

2019 ◽

Cited By ~ 1

Author(s):

Kristian Breili ◽

Matthew James Ross Simpson ◽

Erlend Klokkervold ◽

Oda Roaldsdotter Ravndal

Keyword(s):

At Risk ◽

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

Coastal Flooding ◽

High Accuracy ◽

Mapping Method ◽

Water Levels ◽

Climate Services ◽

Elevation Data

Abstract. Using new high accuracy Light Detection and Ranging elevation data we generate coastal flooding maps for Norway. Thus far, we have mapped ~ 80 % of the coast, for which we currently have data of sufficient accuracy to perform our analysis. Although Norway is generally at low risk from sea-level rise largely owing to its steep topography, the maps presented here show that on local scales, many parts of the coast are potentially vulnerable to flooding. There is a considerable amount of infrastructure at risk along the relatively long and complicated coastline. Nationwide we identify a total area of 400 km2, 105,000 buildings, and 510 km of roads that are at risk of flooding from a 200 year storm-surge event at present. These numbers will increase to 610 km2, 137,000, and 1340 km with projected sea-level rise to 2090 (95th percentile of RCP8.5 as recommended in planning). We find that some of our results are likely biased high owing to erroneous mapping (at least for lower water levels close to the tidal datum which delineates the coastline). A comparison of control points from different terrain types indicates that the elevation model has a root mean square error of 0.26 m and is the largest source of uncertainty in our mapping method. The coastal flooding maps and associated statistics are freely available, and alongside the development of coastal climate services, will help communicate the risks of sea-level rise and storm surge to stakeholders. This will in turn aid coastal management and climate adaption work in Norway.

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Effect of Variations in Water Level and Wave Steepness on the Robustness of Wave Overtopping Estimation

Journal of Marine Science and Engineering ◽

10.3390/jmse8020063 ◽

2020 ◽

Vol 8 (2) ◽

pp. 63

Author(s):

Nils B. Kerpen ◽

Karl-Friedrich Daemrich ◽

Oliver Lojek ◽

Torsten Schlurmann

Keyword(s):

Water Level ◽

Wave Spectrum ◽

Water Environment ◽

Physical Modelling ◽

Storm Surges ◽

Water Levels ◽

Coastal Protection ◽

Wave Steepness ◽

Wave Overtopping

The wave overtopping discharge at coastal defense structures is directly linked to the freeboard height. By means of physical modelling, experiments on wave overtopping volumes at sloped coastal structures are customarily determined for constant water levels and static wave steepness conditions (e.g., specific wave spectrum). These experiments are the basis for the formulation of empirically derived and widely acknowledged wave overtopping estimations for practical design purposes. By analysis and laboratory reproduction of typical features from exemplarily regarded real storm surge time series in German coastal waters, the role of non-stationary water level and wave steepness were analyzed and adjusted in experiments. The robustness of wave overtopping estimation formulae (i.e., the capabilities and limitations of such a static projection of dynamic boundary conditions) are outlined. Therefore, the classic static approach is contrasted with data stemming from tests in which both water level and wave steepness were dynamically altered in representative arrangements. The analysis reveals that mean overtopping discharges for simple sloping structures in an almost deep water environment could be robustly estimated for dynamic water level changes by means of the present design formulae. In contrast, the role of dynamic changes of the wave steepness led to a substantial discrepancy of overtopping volumes by a factor of two. This finding opens new discussion on methodology and criteria design of coastal protection infrastructure under dynamic exposure to storm surges and in lieu of alterations stemming from projected sea level rise.

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