Combined Effects of Projected Sea Level Rise, Storm Surge, and Peak River Flows on Water Levels in the Skagit Floodplain

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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Coastal flooding protection will change salt-marsh sedimentation dynamics

10.5194/egusphere-egu21-1639 ◽

2021 ◽

Author(s):

Davide Tognin ◽

Andrea D'Alpaos ◽

Marco Marani ◽

Luca Carniello

Keyword(s):

Salt Marsh ◽

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

Sedimentation Rate ◽

Urban Areas ◽

Storm Surges ◽

Venice Lagoon ◽

Water Levels ◽

Sedimentation Dynamics

Coastal wetlands lie at the interface between submerged and emerged environments and therefore represent unique yet delicate ecosystems. Their existence, resulting from complex interactions between hydrodynamics and sediment dynamics, is challenged by increasing rates of sea-level rise, lowered fluvial sediment input as well as an increasing anthropogenic pressure. The future survival of these peculiar morphologies is becoming even more complicated, because of the construction and planning of coastal defence structures designed to protect urban areas from flooding. Important examples are the flood protection systems built to protect New Orleans (USA), the river Scheldt Estuary (The Netherlands) and Venice (Italy). In this context, understanding the physical processes on which coastal marshes are grounded and how engineering measures can alter them is of extreme importance in order to plan conservation interventions.To understand marsh sedimentation dynamics in flood-regulated environments, we investigated through field observations and modelling the effect of the storm-surge barrier designed to protect the city of Venice, the so-called Mo.S.E. system, which has in fact become operational since October 2020.Sedimentation measurements in different salt marshes of the Venice lagoon carried out in the period October 2018-October 2020 show that more than 70% of yearly sedimentation accumulates during storm-surge conditions, despite their short duration. Moreover, the sedimentation rate displays a highly non-linear increase with marsh inundation intensity, due to the interplay between higher water levels and greater suspended sediment concentration. Barrier operations during storm surges to avoid flooding of urban areas will reduce water levels and marsh inundation. Therefore, we computed sedimentation in a flood-regulated scenario for the same observation period, using the relation we obtained between tidal forcing and sedimentation rate. Our results show that some occasional closures during intense storm surges (70 hours/year on average) suffice to reduce the yearly sedimentation of the same order of magnitude of the relative sea-level rise rate experienced by the Venice lagoon during the last century (2.5 mm/y).We conclude that storm-surge barrier operations can dangerously reduce salt-marsh vertical accretion rate, thus challenging wetland survival in face of increasing sea-level rise.

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High-accuracy coastal flood mapping for Norway using lidar data

Natural Hazards and Earth System Science ◽

10.5194/nhess-20-673-2020 ◽

2020 ◽

Vol 20 (2) ◽

pp. 673-694

Author(s):

Kristian Breili ◽

Matthew James Ross Simpson ◽

Erlend Klokkervold ◽

Oda Roaldsdotter Ravndal

Keyword(s):

At Risk ◽

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

Climate Adaptation ◽

Coastal Flooding ◽

High Accuracy ◽

Water Levels ◽

Land Uplift ◽

Climate Services

Abstract. Using new high-accuracy light detection and ranging (lidar) 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 and land uplift due to glacial isostatic adjustment, 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 adaptation work in Norway.

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The impact of sea level rise on storm surge water levels in the northern part of the German Bight

Coastal Engineering ◽

10.1016/j.coastaleng.2014.12.002 ◽

2015 ◽

Vol 96 ◽

pp. 118-131 ◽

Cited By ~ 55

Author(s):

A. Arns ◽

T. Wahl ◽

S. Dangendorf ◽

J. Jensen

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

German Bight ◽

Water Levels ◽

The Impact

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Effects of mean sea level rise and tidal flat growth on tides and storm surge events in the Elbe estuary

10.5194/egusphere-egu21-9498 ◽

2021 ◽

Author(s):

Tara Mahavadi ◽

Elisabeth Rudolph ◽

Rita Seiffert ◽

Norbert Winkel

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

Tidal Flat ◽

Tidal Flats ◽

Water Levels ◽

Elbe Estuary ◽

Tidal Amplitude ◽

Tidal Dynamics ◽

Mean Sea Level

Future mean sea level rise will influence tidal dynamics and storm surge events in estuaries. The bathymetry in estuaries and coastal areas will also be affected by mean sea level rise, since it is in a morphodynamic equilibrium with hydrodynamic forces. Tidal flats, which are an important component of coastal protection, will grow to a certain extent with mean sea level rise in case of sufficient sediment availability.With the help of a highly resolved hydrodynamic-numerical model of the German Bight (North Sea), we analyse the potential influence of mean sea level rise and vertical growth of tidal flats on tidal dynamics and storm surge events in the Elbe estuary.The results show an increase of tidal amplitude and storm surge water levels due to mean sea level rise. A bathymetric rise of tidal flats in the German Bight and the mouth of the Elbe estuary leads to a decrease in storm surge water level and tidal amplitude compared to the scenario with sole mean sea level rise without a change in bathymetry. Further analyses show, how geometric parameters of the Elbe estuary are changing due to mean sea level rise and tidal flat growth. These changes in geometry influence tidal dynamics and can therefore be an explanation for the observed changes in tidal amplitude and storm surge water levels.These findings enable a better understanding of future changes in the Elbe estuary and support coastal managers in decision making processes concerning adaptation options to reduce the impacts of climate change.

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Geospatial Risk Assessment of Marine Terminal Infrastructure to Storm Surge Inundation and Sea Level Rise

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198118774234 ◽

2018 ◽

Vol 2672 (11) ◽

pp. 19-29 ◽

Cited By ~ 3

Author(s):

George M. McLeod ◽

Thomas R. Allen ◽

Joshua G. Behr

Keyword(s):

Risk Assessment ◽

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

Storm Surges ◽

Risk Tolerance ◽

Water Levels ◽

Rapid Screening ◽

Tidal Flooding ◽

The Future

Planning resiliency and sustainability of port operations and critical infrastructure requires risk assessment of storm surge exposure and potential sea level rise. An approach for rapid, screening-level assessment is developed to estimate the current and future risk of exposure to severe storm surges posed to marine terminal facilities in Norfolk, Virginia. The approach estimates the vertical elevation of local mean sea level fifty years into the future and attendant increases in potential storm surge heights. Inundation models are designed for baseline water levels and storm surges for category 1–3 hurricanes across five precautionary future sea level rise scenarios. In addition, tidal flooding poses an emerging threat because sea level rise will also force tides to higher elevations, suggesting that today’s extreme high tides may be the future mean high tide and today’s “nuisance” tidal flooding may in the future recur with chronic regularity. Potential tidal flooding levels are also modeled for each sea level scenario. This approach allows a port to assess relative risk tolerance across the range from lesser to more severe flooding events. Maps and tabular information in linked scenarios are used to summarize the extent, pattern, and depth of potential flooding. The methodology and data developed in this study may be applied to inform the timing and placement of planned assets and can be leveraged in the broader pursuit of optimization in support of long-term master planning at marine terminals.

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Sea level rise and its impact on storm surge and tide in Shanghai

MAUSAM ◽

10.54302/mausam.v48i4.4321 ◽

2021 ◽

Vol 48 (4) ◽

pp. 541-554

Author(s):

ZENGHAO QIN

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

Dynamic Models ◽

Spring Tide ◽

Water Levels ◽

Ground Subsidence ◽

Past Century ◽

The Mean ◽

The Impact

Based on both the historical tidal gauge and ground subsidence records for the seven stations in Shanghai region, a non-linear statistical model fitting the variation of the mean annual eustatic sea level (ESL) is established to reveal the characteristics of the ESL in the past century and to estimate the mean annual relative sea level (RSL) in the next five decades by the model extrapolation for Shanghai region. The estimated values of the sea level rises are assessed to be fairly reasonable. The impact of the estimated sea level rise in the coming decades on the storm surges and tides in Shanghai region is numerically computed by using the two-dimensional nonlinear storm surge and tide dynamic models. In addition, on the basis of numerical integration of the same dynamic model, the probable maximum water levels resulting from the RSL in the coming decades are also estimated by the probable optimal combination of the track, intensity, landfall site, incident angle of tropical cyclone and spring tide.

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Integrated extreme sea level events in the Mediterranean coast of Spain

10.5194/egusphere-egu2020-7951 ◽

2020 ◽

Author(s):

Andrea Lira Loarca ◽

Manuel Cobos ◽

Agustín Millares ◽

Giovanni Besio ◽

Asunción Baquerizo

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Storm Surge ◽

Temporal Variability ◽

Climate Change Scenario ◽

Storm Surges ◽

Water Levels ◽

Change Scenario ◽

The World

Coastal areas are one of the most vulnerable regions to climate change given their high exposure to the increasingly frequent extreme sea level (ESL) events and the high population density with around 680 million people (approximately 10% of the world&#8217;s population) residing at less than 10 m above sea level and projected to reach more than one billion by 2050 (IPCC, 2019).Extreme sea level events include the combination of mean sea level, tides, surges and waves set-up. These events that historically occurred once per century are projected to become at least an annual occurrence at most parts of the world during the 21st century. Therefore, a crucial step towards coastal planning and adaption is the understanding of the drivers and impacts of ESL events (Hinkel et al., 2019).Flooding and extreme events in river mouths and their adjacent coastline have a complex nature with oceanic and fluvial processes taking place. Their analysis requires, therefore, the consideration of several physical variables that play a role in water levels such as precipitation, waves, storm surge, and tides. In a climate change scenario, the effects of sea level rise and storminess changes must also be accounted for. The contribution of different processes to ESL events has often been analyzed independently given the difficulty to predict their combined effects.This work focuses on the analysis of ESL events due to the combination of sea level rise, extreme waves, storm surges, tides and river flows in a climate change scenario, following:<ol><li>Projections of wave variables for an ensemble of EURO-CORDEX RCMs under RCP8.5 using WavewatchIII v5.16 (Besio et al., 2019). Wave propagation of local hydrodynamic processes and storm surge with Delft3D.</li> <li>Projections of river flow using a physical-based and distributed hydrological model under the same runs as the wave climate.</li> <li>Joint statistical characterization of local waves and river flows and long-term temporal variability based on the methodology of Lira-Loarca et al. (2020).</li> <li>Analysis of compound extreme sea level and flooding events.</li> </ol>The methodology is applied to a case study in the coast of Granada (Spain) where severe flood events have occurred in recent years. The results highlight the need for an integrated approach encompassing the relevant components of water levels, and specifically sea level rise and waves and the differences in the temporal variability of the significant wave height in a climate change scenario.&#160;&#160;References:<ul><li>Besio et al., 2019. Trends and variability of waves under scenario RCP8.5 in the Mediterranean Sea. 2ndInternational Workshop on Waves, Storm Surges, and Coastal Hazards, Melbourne, Australia</li> <li>Hinkel et al., 2019. Sea level rise and implications for low lying islands, coasts and communities. IPCC SROCC.</li> <li>IPCC, 2019. SPM Special Report on the Ocean and Cryosphere in a Changing Climate.</li> <li>Lira-Loarca et al., 2020. Storm characterization and simulation for damage evolution models of maritime structures. Coastal Engineering, 156, 103620.</li> </ul>

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Economic damages from Hurricane Sandy attributable to sea level rise caused by anthropogenic climate change

Nature Communications ◽

10.1038/s41467-021-22838-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Benjamin H. Strauss ◽

Philip M. Orton ◽

Klaus Bittermann ◽

Maya K. Buchanan ◽

Daniel M. Gilford ◽

...

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

East Coast ◽

The United States ◽

Hurricane Sandy ◽

Water Levels ◽

Anthropogenic Climate Change ◽

Economic Damage ◽

Sea Levels

AbstractIn 2012, Hurricane Sandy hit the East Coast of the United States, creating widespread coastal flooding and over $60 billion in reported economic damage. The potential influence of climate change on the storm itself has been debated, but sea level rise driven by anthropogenic climate change more clearly contributed to damages. To quantify this effect, here we simulate water levels and damage both as they occurred and as they would have occurred across a range of lower sea levels corresponding to different estimates of attributable sea level rise. We find that approximately $8.1B ($4.7B–$14.0B, 5th–95th percentiles) of Sandy’s damages are attributable to climate-mediated anthropogenic sea level rise, as is extension of the flood area to affect 71 (40–131) thousand additional people. The same general approach demonstrated here may be applied to impact assessments for other past and future coastal storms.

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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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