Coastal Flood Assessment Due to Sea Level Rise and Extreme Storm Events - Case Study of the Atlantic Coast of Portugal Mainland

Portugal’s mainland has hundreds of thousands of people living in the Atlantic coastal zone, with numerous high economic value activities and a high number of infrastructures that must be adapted and protected from natural coastal hazards, namely, extreme storms and sea level rise (SLR). In the context of climate change adaptation strategies, a reliable and accurate assessment of the physical vulnerability to SLR is crucial. This study is a contribution to the implementation of flooding standards imposed by the European Directive 2007/60/EC, which requires each member state to assess the risk associated to SLR and floods caused by extreme events. Therefore, coastal hazard on the Atlantic Coast of Portugal’s mainland was evaluated for 2025, 2050, and 2100 over the whole extension due to SLR, with different sea level scenarios for different extreme event return periods. A coastal probabilistic flooding map was produced based on the developed probabilistic cartography methodology using geographic information system (GIS) technology. The Extreme Flood Hazard Index (EFHI) was determined on probabilistic flood bases using five probability intervals of 20% amplitude. For a given SLR scenario, the EFHI is expressed, on the probabilistic flooding maps for an extreme tidal maximum level, by five hazard classes ranging from 1 (Very Low) to 5 (Extreme).

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Applying principles of uncertainty within coastal hazard assessments to better support coastal adaptation

10.26686/wgtn.14349251.v1 ◽

2021 ◽

Author(s):

SA Stephens ◽

RG Bell ◽

Judith Lawrence

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Flood Hazard ◽

Coastal Flooding ◽

Coastal Hazards ◽

Time Range ◽

Coastal Hazard ◽

Adaptive Planning ◽

Groundwater Levels ◽

Hazard Assessments

© 2017 by the authors. Coastal hazards result from erosion of the shore, or flooding of low-elevation land when storm surges combine with high tides and/or large waves. Future sea-level rise will greatly increase the frequency and depth of coastal flooding and will exacerbate erosion and raise groundwater levels, forcing vulnerable communities to adapt. Communities, local councils and infrastructure operators will need to decide when and how to adapt. The process of decision making using adaptive pathways approaches, is now being applied internationally to plan for adaptation over time by anticipating tipping points in the future when planning objectives are no longer being met. This process requires risk and uncertainty considerations to be transparent in the scenarios used in adaptive planning. We outline a framework for uncertainty identification and management within coastal hazard assessments. The framework provides a logical flow from the land use situation, to the related level of uncertainty as determined by the situation, to which hazard scenarios to model, to the complexity level of hazard modeling required, and to the possible decision type. Traditionally, coastal flood hazard maps show inundated areas only. We present enhanced maps of flooding depth and frequency which clearly show the degree of hazard exposure, where that exposure occurs, and how the exposure changes with sea-level rise, to better inform adaptive planning processes. The new uncertainty framework and mapping techniques can better inform identification of trigger points for adaptation pathways planning and their expected time range, compared to traditional coastal flooding hazard assessments.

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Applying principles of uncertainty within coastal hazard assessments to better support coastal adaptation

10.26686/wgtn.14349251 ◽

2021 ◽

Author(s):

SA Stephens ◽

RG Bell ◽

Judith Lawrence

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Flood Hazard ◽

Coastal Flooding ◽

Coastal Hazards ◽

Time Range ◽

Coastal Hazard ◽

Adaptive Planning ◽

Groundwater Levels ◽

Hazard Assessments

© 2017 by the authors. Coastal hazards result from erosion of the shore, or flooding of low-elevation land when storm surges combine with high tides and/or large waves. Future sea-level rise will greatly increase the frequency and depth of coastal flooding and will exacerbate erosion and raise groundwater levels, forcing vulnerable communities to adapt. Communities, local councils and infrastructure operators will need to decide when and how to adapt. The process of decision making using adaptive pathways approaches, is now being applied internationally to plan for adaptation over time by anticipating tipping points in the future when planning objectives are no longer being met. This process requires risk and uncertainty considerations to be transparent in the scenarios used in adaptive planning. We outline a framework for uncertainty identification and management within coastal hazard assessments. The framework provides a logical flow from the land use situation, to the related level of uncertainty as determined by the situation, to which hazard scenarios to model, to the complexity level of hazard modeling required, and to the possible decision type. Traditionally, coastal flood hazard maps show inundated areas only. We present enhanced maps of flooding depth and frequency which clearly show the degree of hazard exposure, where that exposure occurs, and how the exposure changes with sea-level rise, to better inform adaptive planning processes. The new uncertainty framework and mapping techniques can better inform identification of trigger points for adaptation pathways planning and their expected time range, compared to traditional coastal flooding hazard assessments.

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Impact Assessment Analysis of Sea Level Rise in Denmark: A Case Study of Falster Island, Guldborgsund

Sustainability ◽

10.3390/su13137503 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7503

Author(s):

Alexander Boest-Petersen ◽

Piotr Michalak ◽

Jamal Jokar Arsanjani

Keyword(s):

Climate Change ◽

Impact Assessment ◽

Sea Level Rise ◽

Sea Level ◽

Alternative Methods ◽

Projection Data ◽

Storm Events ◽

Cascading Effects ◽

Local Levels

Anthropogenically-induced climate change is expected to be the contributing cause of sea level rise and severe storm events in the immediate future. While Danish authorities have downscaled the future oscillation of sea level rise across Danish coast lines in order to empower the coastal municipalities, there is a need to project the local cascading effects on different sectors. Using geospatial analysis and climate change projection data, we developed a proposed workflow to analyze the impacts of sea level rise in the coastal municipalities of Guldborgsund, located in Southeastern Denmark as a case study. With current estimates of sea level rise and storm surge events, the island of Falster can expect to have up to 19% of its landmass inundated, with approximately 39% of the population experiencing sea level rise directly. Developing an analytical workflow can allow stakeholders to understand the extent of expected sea level rise and consider alternative methods of prevention at the national and local levels. The proposed approach along with the choice of data and open source tools can empower other communities at risk of sea level rise to plan their adaptation.

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Impact of climate change on New York City’s coastal flood hazard: Increasing flood heights from the preindustrial to 2300 CE

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1703568114 ◽

2017 ◽

Vol 114 (45) ◽

pp. 11861-11866 ◽

Cited By ~ 73

Author(s):

Andra J. Garner ◽

Michael E. Mann ◽

Kerry A. Emanuel ◽

Robert E. Kopp ◽

Ning Lin ◽

...

Keyword(s):

New York ◽

New York City ◽

Sea Level Rise ◽

Sea Level ◽

Tropical Cyclones ◽

York City ◽

Flood Hazard ◽

Storm Surges ◽

Cmip5 Models ◽

Tidal Level

The flood hazard in New York City depends on both storm surges and rising sea levels. We combine modeled storm surges with probabilistic sea-level rise projections to assess future coastal inundation in New York City from the preindustrial era through 2300 CE. The storm surges are derived from large sets of synthetic tropical cyclones, downscaled from RCP8.5 simulations from three CMIP5 models. The sea-level rise projections account for potential partial collapse of the Antarctic ice sheet in assessing future coastal inundation. CMIP5 models indicate that there will be minimal change in storm-surge heights from 2010 to 2100 or 2300, because the predicted strengthening of the strongest storms will be compensated by storm tracks moving offshore at the latitude of New York City. However, projected sea-level rise causes overall flood heights associated with tropical cyclones in New York City in coming centuries to increase greatly compared with preindustrial or modern flood heights. For the various sea-level rise scenarios we consider, the 1-in-500-y flood event increases from 3.4 m above mean tidal level during 1970–2005 to 4.0–5.1 m above mean tidal level by 2080–2100 and ranges from 5.0–15.4 m above mean tidal level by 2280–2300. Further, we find that the return period of a 2.25-m flood has decreased from ∼500 y before 1800 to ∼25 y during 1970–2005 and further decreases to ∼5 y by 2030–2045 in 95% of our simulations. The 2.25-m flood height is permanently exceeded by 2280–2300 for scenarios that include Antarctica’s potential partial collapse.

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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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Living Beside the Rising Tide: Adapting to Sea Level Rise in Auckland, New Zealand

10.26686/wgtn.16993600.v1 ◽

2021 ◽

Author(s):

◽

Georgina Hart

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Dynamic Change ◽

Regional Scale ◽

Climate System ◽

Coastal Hazard ◽

Mission Bay ◽

Coastal Adaptation ◽

Hazard Risk ◽

Auckland Region

<p>The Earth's climate system is entering a period of dynamic change after millennia of relatively stable climate. Coastal communities will need to adapt to dynamically shifting coastal environments as the climate system changes and sea levels rise. This study adds to a growing literature that investigates coastal vulnerability, adaptation, and resilience to climate change. It investigates regional scale social and institutional barriers to adaptation to sea level rise; examines the exposure, sensitivity and adaptation options at two coastal settlements in the Auckland region – Mission Bay/Kohimarama and Kawakawa Bay; and it analyses coastal adaptation response options from a resilience perspective. Mission Bay/Kohimarama and Kawakawa Bay, Auckland will experience increasing coastal hazard risk as the numbers of people and property potentially affected by storm events increases as sea level rises. Findings from the present study suggest that existing settlements in the Auckland region may already be 'locked in' to a coastal adaptation approach focused on maintaining the current coastline through coastal stabilisation, an approach that will decrease community resilience and increase vulnerability in the long term, even if this is found to be a successful response in the short term. Retreat offers an alternative approach that is strongly aligned with reducing community vulnerability and increasing resilience; however, strong opposition from communities to any retreat approach is expected. Developing trusted climate science information, education around coastal hazard risk, and participatory community led decision-making are identified as central enablers for a retreat approach to be included as a viable coastal adaptation option for communities in the Auckland region.</p>

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The Climate Vulnerabilities of Global Nuclear Power

Global Environmental Politics ◽

10.1162/glep_a_00527 ◽

2019 ◽

Vol 19 (4) ◽

pp. 3-13 ◽

Cited By ~ 1

Author(s):

Sarah M. Jordaan ◽

Afreen Siddiqi ◽

William Kakenmaster ◽

Alice C. Hill

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Nuclear Power ◽

Power Plants ◽

Extreme Event ◽

International Standards ◽

Plant Design ◽

Low Carbon ◽

And Sea Level

Nuclear power—a source of low-carbon electricity—is exposed to increasing risks from climate change. Intensifying storms, droughts, extreme precipitation, wildfires, higher temperatures, and sea-level rise threaten supply disruptions and facility damage. Approximately 64 percent of installed capacity commenced operation between thirty and forty-eight years ago, before climate change was considered in plant design or construction. Globally, 516 million people reside within a fifty mile (80 km) radius of at least one operating nuclear power plant, and 20 million reside within a ten mile (16 km) radius, and could face health and safety risks resulting from an extreme event induced by climate change. Roughly 41 percent of nuclear power plants operate near seacoasts, making them vulnerable to increasing storm intensity and sea-level rise. Inland plants face exposure to other climate risks, such as increasingly severe wildfires and warmer water temperatures. No entity has responsibility for conducting risk assessments that adequately evaluate the climate vulnerabilities of nuclear power and the subsequent threats to international energy security, the environment, and human health. A comprehensive risk assessment by international agencies and the development of national and international standards is necessary to mitigate risks for new and existing plants.

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Application of STORMTOOLS Coastal Environmental Risk Index (CERI) to Inform State and Local Planning and Decision Making along the Southern RI Shoreline

Journal of Marine Science and Engineering ◽

10.3390/jmse8040295 ◽

2020 ◽

Vol 8 (4) ◽

pp. 295

Author(s):

Malcolm L. Spaulding ◽

Annette Grilli ◽

Chris Damon ◽

Teresa Crean ◽

Grover Fugate

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Rhode Island ◽

Environmental Risk ◽

Structural Damage ◽

Risk Index ◽

Atlantic Coast ◽

Wave Model ◽

Flood Plain ◽

State And Local

STORMTOOLS coastal environmental risk index (CERI) was applied to communities located along the southern coast of Rhode Island (RI) to determine the risk to structures located in the flood plain. CERI uses estimates of the base flood elevation (BFE), explicitly including the effects of sea level rise (SLR); details on the structure types, from the E911 emergency data base/parcel data, and associated first floor elevation (FFE); and damage curves from the US Army Corp of Engineers North Atlantic Coast Comprehensive Study (NACCS) to determine the damages to structures for the study area. Surge levels and associated offshore waves used to determine BFEs were obtained from the NACCS hydrodynamic and wave model predictions. The impacts of sea level rise and coastal erosion on flooding were modeled using XBeach and STWAVE and validated by observations at selected locations along the coastline. CERI estimated the structural damage to each structure in the coastal flood plain for 100 yr flooding with SLR ranging from 0 to 10 ft. The number of structures at risk was estimated to increase approximate linearly from 3700 for no SLR to about 8000 for 10 ft SLR, with about equal percentages for each of the four coastal communities (Narragansett, South Kingstown, Charlestown, and Westerly, Rhode Island (RI)). The majority of the structures in the flood plain are single/story residences without (41%) and with (46%) basements (total 87%; structures with basements are the most vulnerable). Less vulnerable are structures elevated on piles with 8.8% of the total. The remaining are commercial structures principally located either in the Port of Galilee and or Watch Hill. The analysis showed that about 20% of the structures in the 100 yr flood plain are estimated to be damaged at 50% or greater. This increases to 55% of structures as SLR rises to 5 ft. At higher SLR values the percent damaged at 50% or greater slowly declines to 45% at 10 ft SLR. This behavior is a result of the number of homes below MSL increasing dramatically as SLR values moves higher than 5 ft and thus being removed from the structures damaged pool. Generalized CERI risk maps have developed to allow the managers to determine the broad risk of siting structures at any location in their communities. CERI has recently become available as a mobile phone App, facilitating the ability of state and local decision makers and the public to determine the risk of locating a selected building type at any location in their communities.

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Variations in Persistence and Regenerative Zones in Coastal Forests Triggered by Sea Level Rise and Storms

Remote Sensing ◽

10.3390/rs11172019 ◽

2019 ◽

Vol 11 (17) ◽

pp. 2019 ◽

Cited By ~ 3

Author(s):

Sergio Fagherazzi ◽

Giovanna Nordio ◽

Keila Munz ◽

Daniele Catucci ◽

William S. Kearney

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Forest Disturbance ◽

Remote Sensing Data ◽

Storm Events ◽

Coastal Forests ◽

The North ◽

Significant Difference

Retreat of coastal forests in relation to sea level rise has been widely documented. Recent work indicates that coastal forests on the Delmarva Peninsula, United States, can be differentiated into persistence and regenerative zones as a function of sea-level rise and storm events. In the lower persistence zone trees cannot regenerate because of frequent flooding and high soil salinity. This study aims to verify the existence of these zones using spectral remote sensing data, and determine whether the effect of large storm events that cause damage to these forests can be detected from satellite images. Spectral analysis confirms a significant difference in average Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) values in the proposed persistence and regenerative zones. Both NDVI and NDWI indexes decrease after storms triggering a surge above 1.3 m with respect to the North American Vertical Datum of 1988 (NAVD88). NDWI values decrease more, suggesting that this index is better suited to detect the effect of hurricanes on coastal forests. In the regenerative zone, both NDVI and NDWI values recover three years after a storm, while in the persistence zone the NDVI and NDWI values keep decreasing, possibly due to sea level rise causing vegetation stress. As a result, the forest resilience to storms in the persistence zone is lower than in the regenerative zone. Our findings corroborate the ecological ratchet model of coastal forest disturbance.

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